io-ts - npm Package Compare versions

Comparing version 2.2.6 to 2.2.7

CHANGELOG.md

@@ -17,2 +17,29 @@ # Changelog
 
+# 2.2.7
+
+- **Experimental**
+  - add `DecodeError` module (@gcanti)
+  - add `FreeSemigroup` module (@gcanti)
+  - add `TaskDecoder` module (@gcanti)
+  - add `Kleisli` module (@gcanti)
+  - add `KleisliDecoder` module (@gcanti)
+  - add `KleisliTaskDecoder` module (@gcanti)
+  - (\*) remove `NaN` from `number` instances (@gcanti)
+  - (\*) remove `Tree` module (@gcanti)
+  - (\*) make `Json` type immutable (@gcanti)
+  - `Decoder`
+    - (\*) remove `never` (@gcanti)
+    - (\*) make `parse` pipeable and change its `parser` argument (@gcanti)
+    - (\*) change `DecoderError` (@gcanti)
+    - (\*) remove `withExpected` in favour of `mapLeftWithInput` (@gcanti)
+  - `Guard`
+    - (\*) remove `never` (@gcanti)
+  - `Schemable`
+    - (\*) better `literal` signature (@gcanti)
+    - (\*) better `union` signature (@gcanti)
+    - (\*) make intersections pipeables (@gcanti)
+    - (\*) make refinements pipeables (@gcanti)
+
+(\*) breaking change
+
 # 2.2.6
@@ -19,0 +46,0 @@

es6/Codec.d.ts

 /**
+ * **This module is experimental**
+ *
+ * Experimental features are published in order to get early feedback from the community, see these tracking
+ * [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
+ *
+ * A feature tagged as _Experimental_ is in a high state of flux, you're at risk of it changing without notice.
+ *
  * @since 2.2.3
@@ -41,3 +48,3 @@ */
  */
-export declare function literal<A extends ReadonlyArray<Literal>>(...values: A): Codec<A[number], A[number]>;
+export declare function literal<A extends readonly [Literal, ...Array<Literal>]>(...values: A): Codec<A[number], A[number]>;
 /**
@@ -72,3 +79,3 @@ * @category primitives
  */
-export declare function withExpected<O, A>(codec: Codec<O, A>, expected: (actual: unknown, e: D.DecodeError) => D.DecodeError): Codec<O, A>;
+export declare const mapLeftWithInput: (f: (actual: unknown, e: D.DecodeError) => D.DecodeError) => <O, A>(codec: Codec<O, A>) => Codec<O, A>;
 /**
@@ -78,3 +85,3 @@ * @category combinators
  */
-export declare function refinement<O, A, B extends A>(from: Codec<O, A>, refinement: (a: A) => a is B, expected: string): Codec<O, B>;
+export declare const refine: <A, B extends A>(refinement: (a: A) => a is B, id: string) => <O>(from: Codec<O, A>) => Codec<O, B>;
 /**
@@ -126,3 +133,3 @@ * @category combinators
  */
-export declare function intersection<O, A, P, B>(left: Codec<O, A>, right: Codec<P, B>): Codec<O & P, A & B>;
+export declare const intersect: <P, B>(right: Codec<P, B>) => <O, A>(left: Codec<O, A>) => Codec<O & P, A & B>;
 /**
@@ -129,0 +136,0 @@ * @category combinators

es6/Codec.js

 import * as D from './Decoder';
 import * as E from './Encoder';
 import { identity } from 'fp-ts/es6/function';
+import { pipe } from 'fp-ts/es6/pipeable';
 // -------------------------------------------------------------------------------------
@@ -73,5 +74,3 @@ // constructors
  */
-export function withExpected(codec, expected) {
-    return make(D.withExpected(codec, expected), codec);
-}
+export var mapLeftWithInput = function (f) { return function (codec) { return make(pipe(codec, D.mapLeftWithInput(f)), codec); }; };
 /**
@@ -81,5 +80,6 @@ * @category combinators
  */
-export function refinement(from, refinement, expected) {
-    return make(D.refinement(from, refinement, expected), from);
-}
+export var refine = function (refinement, id) {
+    var refine = D.refine(refinement, id);
+    return function (from) { return make(refine(from), from); };
+};
 /**
@@ -140,5 +140,7 @@ * @category combinators
  */
-export function intersection(left, right) {
-    return make(D.intersection(left, right), E.intersection(left, right));
-}
+export var intersect = function (right) {
+    var intersectD = D.intersect(right);
+    var intersectE = E.intersect(right);
+    return function (left) { return make(intersectD(left), intersectE(left)); };
+};
 /**
@@ -145,0 +147,0 @@ * @category combinators

es6/Decoder.d.ts

 /**
- * @since 2.2.0
+ * **This module is experimental**
+ *
+ * Experimental features are published in order to get early feedback from the community, see these tracking
+ * [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
+ *
+ * A feature tagged as _Experimental_ is in a high state of flux, you're at risk of it changing without notice.
+ *
+ * @since 2.2.7
  */
+import { Alt1 } from 'fp-ts/es6/Alt';
 import * as E from 'fp-ts/es6/Either';
-import { NonEmptyArray } from 'fp-ts/es6/NonEmptyArray';
-import { Forest, Tree } from 'fp-ts/es6/Tree';
+import { Functor1 } from 'fp-ts/es6/Functor';
 import * as G from './Guard';
-import { Literal, Schemable1, WithRefinement1, WithUnion1, WithUnknownContainers1 } from './Schemable';
-import { Functor1 } from 'fp-ts/es6/Functor';
-import { Alt1 } from 'fp-ts/es6/Alt';
-import Either = E.Either;
+import * as KD from './KleisliDecoder';
+import { Literal, Schemable1, WithRefine1, WithUnion1, WithUnknownContainers1 } from './Schemable';
 /**
  * @category model
- * @since 2.2.0
+ * @since 2.2.7
  */
-export interface Decoder<A> {
-    readonly decode: (u: unknown) => Either<DecodeError, A>;
+export interface Decoder<A> extends KD.KleisliDecoder<unknown, A> {
 }
 /**
- * @since 2.2.0
- */
-export declare type TypeOf<D> = D extends Decoder<infer A> ? A : never;
-/**
  * @category DecodeError
- * @since 2.2.2
+ * @since 2.2.7
  */
-export interface DecodeError extends NonEmptyArray<Tree<string>> {
-}
+export declare type DecodeError = KD.DecodeError;
 /**
  * @category DecodeError
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function tree<A>(value: A, forest?: Forest<A>): Tree<A>;
+export declare const error: (actual: unknown, message: string) => DecodeError;
 /**
  * @category DecodeError
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function success<A>(a: A): Either<DecodeError, A>;
+export declare const success: <A>(a: A) => E.Either<DecodeError, A>;
 /**
  * @category DecodeError
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function failure<A = never>(message: string): Either<DecodeError, A>;
+export declare const failure: <A = never>(actual: unknown, message: string) => E.Either<DecodeError, A>;
 /**
- * @category DecodeError
- * @since 2.2.2
- */
-export declare function isNotEmpty<A>(as: ReadonlyArray<A>): as is NonEmptyArray<A>;
-/**
  * @category constructors
- * @since 2.2.3
+ * @since 2.2.7
  */
-export declare function of<A>(a: A): Decoder<A>;
+export declare const fromGuard: <A>(guard: G.Guard<A>, expected: string) => Decoder<A>;
 /**
  * @category constructors
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function fromGuard<A>(guard: G.Guard<A>, expected: string): Decoder<A>;
+export declare const literal: <A extends readonly [Literal, ...Array<Literal>]>(...values: A) => Decoder<A[number]>;
 /**
- * @category constructors
- * @since 2.2.0
- */
-export declare function literal<A extends ReadonlyArray<Literal>>(...values: A): Decoder<A[number]>;
-/**
  * @category primitives
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare const never: Decoder<never>;
-/**
- * @category primitives
- * @since 2.2.0
- */
 export declare const string: Decoder<string>;
 /**
  * @category primitives
- * @since 2.2.0
+ * @since 2.2.7
  */
@@ -81,3 +65,3 @@ export declare const number: Decoder<number>;
  * @category primitives
- * @since 2.2.0
+ * @since 2.2.7
  */
@@ -87,3 +71,3 @@ export declare const boolean: Decoder<boolean>;
  * @category primitives
- * @since 2.2.0
+ * @since 2.2.7
  */
@@ -93,3 +77,3 @@ export declare const UnknownArray: Decoder<Array<unknown>>;
  * @category primitives
- * @since 2.2.0
+ * @since 2.2.7
  */
@@ -99,82 +83,75 @@ export declare const UnknownRecord: Decoder<Record<string, unknown>>;
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function withExpected<A>(decoder: Decoder<A>, expected: (actual: unknown, e: DecodeError) => DecodeError): Decoder<A>;
+export declare const mapLeftWithInput: (f: (input: unknown, e: DecodeError) => DecodeError) => <A>(decoder: Decoder<A>) => Decoder<A>;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function refinement<A, B extends A>(from: Decoder<A>, refinement: (a: A) => a is B, expected: string): Decoder<B>;
+export declare const refine: <A, B extends A>(refinement: (a: A) => a is B, id: string) => (from: Decoder<A>) => Decoder<B>;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function parse<A, B>(from: Decoder<A>, parser: (a: A) => Either<string, B>): Decoder<B>;
+export declare const parse: <A, B>(parser: (a: A) => E.Either<DecodeError, B>) => (from: Decoder<A>) => Decoder<B>;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function nullable<A>(or: Decoder<A>): Decoder<null | A>;
+export declare const nullable: <A>(or: Decoder<A>) => Decoder<null | A>;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function type<A>(properties: {
-    [K in keyof A]: Decoder<A[K]>;
-}): Decoder<{
-    [K in keyof A]: A[K];
-}>;
+export declare const type: <A>(properties: { [K in keyof A]: Decoder<A[K]>; }) => Decoder<{ [K_1 in keyof A]: A[K_1]; }>;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function partial<A>(properties: {
-    [K in keyof A]: Decoder<A[K]>;
-}): Decoder<Partial<{
-    [K in keyof A]: A[K];
-}>>;
+export declare const partial: <A>(properties: { [K in keyof A]: Decoder<A[K]>; }) => Decoder<Partial<{ [K_1 in keyof A]: A[K_1]; }>>;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function record<A>(codomain: Decoder<A>): Decoder<Record<string, A>>;
+export declare const array: <A>(items: Decoder<A>) => Decoder<A[]>;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function array<A>(items: Decoder<A>): Decoder<Array<A>>;
+export declare const record: <A>(codomain: Decoder<A>) => Decoder<Record<string, A>>;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function tuple<A extends ReadonlyArray<unknown>>(...components: {
+export declare const tuple: <A extends readonly unknown[]>(...components: { [K in keyof A]: Decoder<A[K]>; }) => Decoder<A>;
+/**
+ * @category combinators
+ * @since 2.2.7
+ */
+export declare const union: <A extends readonly [unknown, ...Array<unknown>]>(...members: {
     [K in keyof A]: Decoder<A[K]>;
-}): Decoder<A>;
+}) => Decoder<A[number]>;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function intersection<A, B>(left: Decoder<A>, right: Decoder<B>): Decoder<A & B>;
+export declare const intersect: <B>(right: Decoder<B>) => <A>(left: Decoder<A>) => Decoder<A & B>;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function lazy<A>(id: string, f: () => Decoder<A>): Decoder<A>;
+export declare const sum: <T extends string>(tag: T) => <A>(members: { [K in keyof A]: Decoder<A[K]>; }) => Decoder<A[keyof A]>;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function sum<T extends string>(tag: T): <A>(members: {
-    [K in keyof A]: Decoder<A[K]>;
-}) => Decoder<A[keyof A]>;
+export declare const lazy: <A>(id: string, f: () => Decoder<A>) => Decoder<A>;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function union<A extends ReadonlyArray<unknown>>(...members: {
-    [K in keyof A]: Decoder<A[K]>;
-}): Decoder<A[number]>;
+export declare const compose: <A, B>(to: KD.KleisliDecoder<A, B>) => (from: Decoder<A>) => Decoder<B>;
 /**
  * @category Functor
- * @since 2.2.0
+ * @since 2.2.7
  */
@@ -184,8 +161,8 @@ export declare const map: <A, B>(f: (a: A) => B) => (fa: Decoder<A>) => Decoder<B>;
  * @category Alt
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare const alt: <A>(that: () => Decoder<A>) => (fa: Decoder<A>) => Decoder<A>;
+export declare const alt: <A>(that: () => Decoder<A>) => (me: Decoder<A>) => Decoder<A>;
 /**
  * @category instances
- * @since 2.2.0
+ * @since 2.2.7
  */
@@ -195,3 +172,3 @@ export declare const URI = "io-ts/Decoder";
  * @category instances
- * @since 2.2.0
+ * @since 2.2.7
  */
@@ -206,3 +183,3 @@ export declare type URI = typeof URI;
  * @category instances
- * @since 2.2.3
+ * @since 2.2.7
  */
@@ -212,3 +189,3 @@ export declare const functorDecoder: Functor1<URI>;
  * @category instances
- * @since 2.2.3
+ * @since 2.2.7
  */
@@ -218,4 +195,12 @@ export declare const altDecoder: Alt1<URI>;
  * @category instances
- * @since 2.2.3
+ * @since 2.2.7
  */
-export declare const schemableDecoder: Schemable1<URI> & WithUnknownContainers1<URI> & WithUnion1<URI> & WithRefinement1<URI>;
+export declare const schemableDecoder: Schemable1<URI> & WithUnknownContainers1<URI> & WithUnion1<URI> & WithRefine1<URI>;
+/**
+ * @since 2.2.7
+ */
+export declare type TypeOf<D> = KD.TypeOf<D>;
+/**
+ * @since 2.2.7
+ */
+export declare const draw: (e: DecodeError) => string;

es6/Decoder.js

@@ -1,41 +0,22 @@
-/**
- * @since 2.2.0
- */
 import * as E from 'fp-ts/es6/Either';
 import { pipe } from 'fp-ts/es6/pipeable';
+import * as DE from './DecodeError';
+import * as FS from './FreeSemigroup';
 import * as G from './Guard';
-import { memoize } from './Schemable';
-var empty = [];
+import * as KD from './KleisliDecoder';
 /**
  * @category DecodeError
- * @since 2.2.0
+ * @since 2.2.7
  */
-export function tree(value, forest) {
-    if (forest === void 0) { forest = empty; }
-    return {
-        value: value,
-        forest: forest
-    };
-}
+export var error = KD.error;
 /**
  * @category DecodeError
- * @since 2.2.0
+ * @since 2.2.7
  */
-export function success(a) {
-    return E.right(a);
-}
+export var success = KD.success;
 /**
  * @category DecodeError
- * @since 2.2.0
+ * @since 2.2.7
  */
-export function failure(message) {
-    return E.left([tree(message)]);
-}
-/**
- * @category DecodeError
- * @since 2.2.2
- */
-export function isNotEmpty(as) {
-    return as.length > 0;
-}
+export var failure = KD.failure;
 // -------------------------------------------------------------------------------------
@@ -46,34 +27,10 @@ // constructors
  * @category constructors
- * @since 2.2.3
+ * @since 2.2.7
  */
-export function of(a) {
-    return {
-        decode: function () { return success(a); }
-    };
-}
+export var fromGuard = function (guard, expected) { return KD.fromRefinement(guard.is, expected); };
 /**
  * @category constructors
- * @since 2.2.0
+ * @since 2.2.7
  */
-export function fromGuard(guard, expected) {
-    return {
-        decode: function (u) { return (guard.is(u) ? success(u) : failure("cannot decode " + JSON.stringify(u) + ", should be " + expected)); }
-    };
-}
-/**
- * @category constructors
- * @since 2.2.0
- */
-export function literal() {
-    var _a;
-    var values = [];
-    for (var _i = 0; _i < arguments.length; _i++) {
-        values[_i] = arguments[_i];
-    }
-    if (values.length === 0) {
-        return never;
-    }
-    var expected = values.map(function (value) { return JSON.stringify(value); }).join(' | ');
-    return fromGuard((_a = G.schemableGuard).literal.apply(_a, values), expected);
-}
+export var literal = KD.literal;
 // -------------------------------------------------------------------------------------
@@ -84,30 +41,41 @@ // primitives
  * @category primitives
- * @since 2.2.0
+ * @since 2.2.7
  */
-export var never = fromGuard(G.never, 'never');
+export var string = 
+/*#__PURE__*/
+fromGuard(G.string, 'string');
 /**
  * @category primitives
- * @since 2.2.0
+ * @since 2.2.7
  */
-export var string = fromGuard(G.string, 'string');
+export var number = 
+/*#__PURE__*/
+fromGuard(G.number, 'number');
 /**
  * @category primitives
- * @since 2.2.0
+ * @since 2.2.7
  */
-export var number = fromGuard(G.number, 'number');
+export var boolean = 
+/*#__PURE__*/
+fromGuard(G.boolean, 'boolean');
 /**
  * @category primitives
- * @since 2.2.0
+ * @since 2.2.7
  */
-export var boolean = fromGuard(G.boolean, 'boolean');
+export var UnknownArray = 
+/*#__PURE__*/
+fromGuard(G.UnknownArray, 'Array<unknown>');
 /**
  * @category primitives
- * @since 2.2.0
+ * @since 2.2.7
  */
-export var UnknownArray = fromGuard(G.UnknownArray, 'Array<unknown>');
+export var UnknownRecord = 
+/*#__PURE__*/
+fromGuard(G.UnknownRecord, 'Record<string, unknown>');
 /**
- * @category primitives
- * @since 2.2.0
+ * @internal
  */
-export var UnknownRecord = fromGuard(G.UnknownRecord, 'Record<string, unknown>');
+export var object = 
+/*#__PURE__*/
+fromGuard(G.object, 'object');
 // -------------------------------------------------------------------------------------
@@ -118,185 +86,51 @@ // combinators
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export function withExpected(decoder, expected) {
-    return {
-        decode: function (u) {
-            return pipe(decoder.decode(u), E.mapLeft(function (nea) { return expected(u, nea); }));
-        }
-    };
-}
+export var mapLeftWithInput = KD.mapLeftWithInput;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export function refinement(from, refinement, expected) {
-    return {
-        decode: function (u) {
-            var e = from.decode(u);
-            if (E.isLeft(e)) {
-                return e;
-            }
-            var a = e.right;
-            return refinement(a) ? success(a) : failure("cannot refine " + JSON.stringify(u) + ", should be " + expected);
-        }
-    };
-}
+export var refine = KD.refine;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export function parse(from, parser) {
-    return {
-        decode: function (u) {
-            var e = from.decode(u);
-            if (E.isLeft(e)) {
-                return e;
-            }
-            var pe = parser(e.right);
-            if (E.isLeft(pe)) {
-                return failure(pe.left);
-            }
-            return pe;
-        }
-    };
-}
+export var parse = KD.parse;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export function nullable(or) {
-    return union(literal(null), or);
-}
+export var nullable = KD.nullable;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export function type(properties) {
-    return {
-        decode: function (u) {
-            var e = UnknownRecord.decode(u);
-            if (E.isLeft(e)) {
-                return e;
-            }
-            else {
-                var r = e.right;
-                var a = {};
-                var errors = [];
-                for (var k in properties) {
-                    var e_1 = properties[k].decode(r[k]);
-                    if (E.isLeft(e_1)) {
-                        errors.push(tree("required property " + JSON.stringify(k), e_1.left));
-                    }
-                    else {
-                        a[k] = e_1.right;
-                    }
-                }
-                return isNotEmpty(errors) ? E.left(errors) : success(a);
-            }
-        }
-    };
-}
+export var type = function (properties) {
+    return pipe(object, compose(KD.type(properties)));
+};
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export function partial(properties) {
-    return {
-        decode: function (u) {
-            var e = UnknownRecord.decode(u);
-            if (E.isLeft(e)) {
-                return e;
-            }
-            else {
-                var r = e.right;
-                var a = {};
-                var errors = [];
-                for (var k in properties) {
-                    // don't add missing properties
-                    if (k in r) {
-                        var rk = r[k];
-                        // don't strip undefined properties
-                        if (rk === undefined) {
-                            a[k] = undefined;
-                        }
-                        else {
-                            var e_2 = properties[k].decode(rk);
-                            if (E.isLeft(e_2)) {
-                                errors.push(tree("optional property " + JSON.stringify(k), e_2.left));
-                            }
-                            else {
-                                a[k] = e_2.right;
-                            }
-                        }
-                    }
-                }
-                return isNotEmpty(errors) ? E.left(errors) : success(a);
-            }
-        }
-    };
-}
+export var partial = function (properties) {
+    return pipe(object, compose(KD.partial(properties)));
+};
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export function record(codomain) {
-    return {
-        decode: function (u) {
-            var e = UnknownRecord.decode(u);
-            if (E.isLeft(e)) {
-                return e;
-            }
-            else {
-                var r = e.right;
-                var a = {};
-                var errors = [];
-                for (var k in r) {
-                    var e_3 = codomain.decode(r[k]);
-                    if (E.isLeft(e_3)) {
-                        errors.push(tree("key " + JSON.stringify(k), e_3.left));
-                    }
-                    else {
-                        a[k] = e_3.right;
-                    }
-                }
-                return isNotEmpty(errors) ? E.left(errors) : success(a);
-            }
-        }
-    };
-}
+export var array = function (items) { return pipe(UnknownArray, compose(KD.array(items))); };
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export function array(items) {
-    return {
-        decode: function (u) {
-            var e = UnknownArray.decode(u);
-            if (E.isLeft(e)) {
-                return e;
-            }
-            else {
-                var us = e.right;
-                var len = us.length;
-                var a = new Array(len);
-                var errors = [];
-                for (var i = 0; i < len; i++) {
-                    var e_4 = items.decode(us[i]);
-                    if (E.isLeft(e_4)) {
-                        errors.push(tree("item " + i, e_4.left));
-                    }
-                    else {
-                        a[i] = e_4.right;
-                    }
-                }
-                return isNotEmpty(errors) ? E.left(errors) : success(a);
-            }
-        }
-    };
-}
+export var record = function (codomain) {
+    return pipe(UnknownRecord, compose(KD.record(codomain)));
+};
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export function tuple() {
+export var tuple = function () {
     var components = [];
@@ -306,137 +140,37 @@ for (var _i = 0; _i < arguments.length; _i++) {
     }
-    return {
-        decode: function (u) {
-            var e = UnknownArray.decode(u);
-            if (E.isLeft(e)) {
-                return e;
-            }
-            var us = e.right;
-            var a = [];
-            var errors = [];
-            for (var i = 0; i < components.length; i++) {
-                var e_5 = components[i].decode(us[i]);
-                if (E.isLeft(e_5)) {
-                    errors.push(tree("component " + i, e_5.left));
-                }
-                else {
-                    a.push(e_5.right);
-                }
-            }
-            return isNotEmpty(errors) ? E.left(errors) : success(a);
-        }
-    };
-}
-function typeOf(x) {
-    return x === null ? 'null' : typeof x;
-}
+    return pipe(UnknownArray, compose(KD.tuple.apply(KD, components)));
+};
 /**
- * @internal
+ * @category combinators
+ * @since 2.2.7
  */
-export function intersect(a, b) {
-    if (a !== undefined && b !== undefined) {
-        var tx = typeOf(a);
-        var ty = typeOf(b);
-        if (tx === 'object' || ty === 'object') {
-            return Object.assign({}, a, b);
-        }
-    }
-    return b;
-}
+export var union = KD.union;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export function intersection(left, right) {
-    return {
-        decode: function (u) {
-            var ea = left.decode(u);
-            var eb = right.decode(u);
-            if (E.isLeft(ea)) {
-                return E.isLeft(eb) ? E.left(ea.left.concat(eb.left)) : ea;
-            }
-            if (E.isLeft(eb)) {
-                return eb;
-            }
-            return success(intersect(ea.right, eb.right));
-        }
-    };
-}
+export var intersect = KD.intersect;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export function lazy(id, f) {
-    var get = memoize(f);
-    return {
-        decode: function (u) {
-            return pipe(get().decode(u), E.mapLeft(function (nea) { return [tree(id, nea)]; }));
-        }
-    };
-}
+export var sum = function (tag) { return function (members) {
+    return pipe(object, compose(KD.sum(tag)(members)));
+}; };
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export function sum(tag) {
-    return function (members) {
-        var keys = Object.keys(members);
-        if (keys.length === 0) {
-            return never;
-        }
-        var expected = keys.map(function (k) { return JSON.stringify(k); }).join(' | ');
-        return {
-            decode: function (u) {
-                var e = UnknownRecord.decode(u);
-                if (E.isLeft(e)) {
-                    return e;
-                }
-                var v = e.right[tag];
-                if (v in members) {
-                    return members[v].decode(u);
-                }
-                return E.left([
-                    tree("required property " + JSON.stringify(tag), [
-                        tree("cannot decode " + JSON.stringify(v) + ", should be " + expected)
-                    ])
-                ]);
-            }
-        };
-    };
-}
+export var lazy = KD.lazy;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export function union() {
-    var members = [];
-    for (var _i = 0; _i < arguments.length; _i++) {
-        members[_i] = arguments[_i];
-    }
-    var len = members.length;
-    if (len === 0) {
-        return never;
-    }
-    return {
-        decode: function (u) {
-            var e = members[0].decode(u);
-            if (E.isRight(e)) {
-                return e;
-            }
-            else {
-                var errors = [tree("member 0", e.left)];
-                for (var i = 1; i < len; i++) {
-                    var e_6 = members[i].decode(u);
-                    if (E.isRight(e_6)) {
-                        return e_6;
-                    }
-                    else {
-                        errors.push(tree("member " + i, e_6.left));
-                    }
-                }
-                return E.left(errors);
-            }
-        }
-    };
-}
+export var compose = KD.compose;
 // -------------------------------------------------------------------------------------
+// non-pipeables
+// -------------------------------------------------------------------------------------
+var map_ = function (fa, f) { return pipe(fa, map(f)); };
+var alt_ = function (me, that) { return pipe(me, alt(that)); };
+// -------------------------------------------------------------------------------------
 // pipeables
@@ -446,22 +180,10 @@ // -------------------------------------------------------------------------------------
  * @category Functor
- * @since 2.2.0
+ * @since 2.2.7
  */
-export var map = function (f) { return function (fa) { return map_(fa, f); }; };
-var map_ = function (fa, f) { return ({
-    decode: function (u) {
-        var e = fa.decode(u);
-        return E.isLeft(e) ? e : E.right(f(e.right));
-    }
-}); };
+export var map = KD.map;
 /**
  * @category Alt
- * @since 2.2.0
+ * @since 2.2.7
  */
-export var alt = function (that) { return function (fa) { return alt_(fa, that); }; };
-var alt_ = function (fx, fy) { return ({
-    decode: function (u) {
-        var e = fx.decode(u);
-        return E.isLeft(e) ? fy().decode(u) : e;
-    }
-}); };
+export var alt = KD.alt;
 // -------------------------------------------------------------------------------------
@@ -472,3 +194,3 @@ // instances
  * @category instances
- * @since 2.2.0
+ * @since 2.2.7
  */
@@ -478,3 +200,3 @@ export var URI = 'io-ts/Decoder';
  * @category instances
- * @since 2.2.3
+ * @since 2.2.7
  */
@@ -487,3 +209,3 @@ export var functorDecoder = {
  * @category instances
- * @since 2.2.3
+ * @since 2.2.7
  */
@@ -497,3 +219,3 @@ export var altDecoder = {
  * @category instances
- * @since 2.2.3
+ * @since 2.2.7
  */
@@ -512,3 +234,3 @@ export var schemableDecoder = {
     tuple: tuple,
-    intersection: intersection,
+    intersect: intersect,
     sum: sum,
@@ -519,3 +241,42 @@ lazy: lazy,
     union: union,
-    refinement: refinement
+    refine: refine
 };
+var empty = [];
+var make = function (value, forest) {
+    if (forest === void 0) { forest = empty; }
+    return ({
+        value: value,
+        forest: forest
+    });
+};
+var drawTree = function (tree) { return tree.value + drawForest('\n', tree.forest); };
+var drawForest = function (indentation, forest) {
+    var r = '';
+    var len = forest.length;
+    var tree;
+    for (var i = 0; i < len; i++) {
+        tree = forest[i];
+        var isLast = i === len - 1;
+        r += indentation + (isLast ? '└' : '├') + '─ ' + tree.value;
+        r += drawForest(indentation + (len > 1 && !isLast ? '│  ' : '   '), tree.forest);
+    }
+    return r;
+};
+var toTree = DE.fold({
+    Leaf: function (input, error) { return make("cannot decode " + JSON.stringify(input) + ", should be " + error); },
+    Key: function (key, kind, errors) { return make(kind + " property " + JSON.stringify(key), toForest(errors)); },
+    Index: function (index, kind, errors) { return make(kind + " index " + index, toForest(errors)); },
+    Member: function (index, errors) { return make("member " + index, toForest(errors)); },
+    Lazy: function (id, errors) { return make("lazy type " + id, toForest(errors)); }
+});
+var toForest = FS.fold(function (value) { return [toTree(value)]; }, function (left, right) { return toForest(left).concat(toForest(right)); });
+/**
+ * @since 2.2.7
+ */
+export var draw = function (e) { return toForest(e).map(drawTree).join('\n'); };
+/**
+ * @internal
+ */
+export var stringify = 
+/*#__PURE__*/
+E.fold(draw, function (a) { return JSON.stringify(a, null, 2); });

es6/Encoder.d.ts

 /**
+ * **This module is experimental**
+ *
+ * Experimental features are published in order to get early feedback from the community, see these tracking
+ * [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
+ *
+ * A feature tagged as _Experimental_ is in a high state of flux, you're at risk of it changing without notice.
+ *
  * @since 2.2.3
@@ -14,10 +21,2 @@ */
 /**
- * @since 2.2.3
- */
-export declare type TypeOf<E> = E extends Encoder<any, infer A> ? A : never;
-/**
- * @since 2.2.3
- */
-export declare type OutputOf<E> = E extends Encoder<infer O, any> ? O : never;
-/**
  * @category constructors
@@ -73,3 +72,3 @@ * @since 2.2.3
  */
-export declare function intersection<O, A, P, B>(left: Encoder<O, A>, right: Encoder<P, B>): Encoder<O & P, A & B>;
+export declare const intersect: <P, B>(right: Encoder<P, B>) => <O, A>(left: Encoder<O, A>) => Encoder<O & P, A & B>;
 /**
@@ -79,3 +78,3 @@ * @category combinators
  */
-export declare function sum<T extends string>(tag: T): <M extends Record<string, Encoder<any, any>>>(members: M) => Encoder<OutputOf<M[keyof M]>, TypeOf<M[keyof M]>>;
+export declare function sum<T extends string>(tag: T): <MS extends Record<string, Encoder<any, any>>>(members: MS) => Encoder<OutputOf<MS[keyof MS]>, TypeOf<MS[keyof MS]>>;
 /**
@@ -121,1 +120,9 @@ * @category combinators
 export declare const categoryEncoder: Category2<URI>;
+/**
+ * @since 2.2.3
+ */
+export declare type TypeOf<E> = E extends Encoder<any, infer A> ? A : never;
+/**
+ * @since 2.2.3
+ */
+export declare type OutputOf<E> = E extends Encoder<infer O, any> ? O : never;

es6/Encoder.js

@@ -1,3 +0,2 @@
-import { intersect } from './Decoder';
-import { memoize } from './Schemable';
+import { memoize, intersect_ } from './Schemable';
 import { identity } from 'fp-ts/es6/function';
@@ -104,7 +103,5 @@ // -------------------------------------------------------------------------------------
  */
-export function intersection(left, right) {
-    return {
-        encode: function (ab) { return intersect(left.encode(ab), right.encode(ab)); }
-    };
-}
+export var intersect = function (right) { return function (left) { return ({
+    encode: function (ab) { return intersect_(left.encode(ab), right.encode(ab)); }
+}); }; };
 /**
@@ -111,0 +108,0 @@ * @category combinators

es6/Eq.d.ts

 import * as E from 'fp-ts/es6/Eq';
-import { Schemable1, WithRefinement1, WithUnknownContainers1 } from './Schemable';
+import { Schemable1, WithRefine1, WithUnknownContainers1 } from './Schemable';
 import Eq = E.Eq;
@@ -81,3 +81,3 @@ /**
  */
-export declare function intersection<A, B>(left: Eq<A>, right: Eq<B>): Eq<A & B>;
+export declare const intersect: <B>(right: E.Eq<B>) => <A>(left: E.Eq<A>) => E.Eq<A & B>;
 /**
@@ -99,2 +99,2 @@ * @category combinators
  */
-export declare const schemableEq: Schemable1<E.URI> & WithUnknownContainers1<E.URI> & WithRefinement1<E.URI>;
+export declare const schemableEq: Schemable1<E.URI> & WithUnknownContainers1<E.URI> & WithRefine1<E.URI>;

es6/Eq.js

 /**
+ * **This module is experimental**
+ *
+ * Experimental features are published in order to get early feedback from the community, see these tracking
+ * [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
+ *
+ * A feature tagged as _Experimental_ is in a high state of flux, you're at risk of it changing without notice.
+ *
  * @since 2.2.2
@@ -102,7 +109,5 @@ */
  */
-export function intersection(left, right) {
-    return {
-        equals: function (x, y) { return left.equals(x, y) && right.equals(x, y); }
-    };
-}
+export var intersect = function (right) { return function (left) { return ({
+    equals: function (x, y) { return left.equals(x, y) && right.equals(x, y); }
+}); }; };
 /**
@@ -155,3 +160,3 @@ * @category combinators
     tuple: tuple,
-    intersection: intersection,
+    intersect: intersect,
     sum: sum,
@@ -161,3 +166,3 @@ lazy: function (_, f) { return lazy(f); },
     UnknownRecord: UnknownRecord,
-    refinement: function (from) { return from; }
+    refine: function () { return function (from) { return from; }; }
 };

es6/Guard.d.ts

@@ -0,6 +1,3 @@
+import { Literal, Schemable1, WithRefine1, WithUnion1, WithUnknownContainers1 } from './Schemable';
 /**
- * @since 2.2.0
- */
-import { Literal, Schemable1, WithRefinement1, WithUnion1, WithUnknownContainers1 } from './Schemable';
-/**
  * @category model
@@ -20,3 +17,3 @@ * @since 2.2.0
  */
-export declare function literal<A extends ReadonlyArray<Literal>>(...values: A): Guard<A[number]>;
+export declare const literal: <A extends readonly [Literal, ...Literal[]]>(...values: A) => Guard<A[number]>;
 /**
@@ -26,9 +23,6 @@ * @category primitives
  */
-export declare const never: Guard<never>;
-/**
- * @category primitives
- * @since 2.2.0
- */
 export declare const string: Guard<string>;
 /**
+ * Note: `NaN` is excluded.
+ *
  * @category primitives
@@ -57,3 +51,3 @@ * @since 2.2.0
  */
-export declare function refinement<A, B extends A>(from: Guard<A>, refinement: (a: A) => a is B): Guard<B>;
+export declare const refine: <A, B extends A>(refinement: (a: A) => a is B) => (from: Guard<A>) => Guard<B>;
 /**
@@ -63,3 +57,3 @@ * @category combinators
  */
-export declare function nullable<A>(or: Guard<A>): Guard<null | A>;
+export declare const nullable: <A>(or: Guard<A>) => Guard<A | null>;
 /**
@@ -69,7 +63,3 @@ * @category combinators
  */
-export declare function type<A>(properties: {
-    [K in keyof A]: Guard<A[K]>;
-}): Guard<{
-    [K in keyof A]: A[K];
-}>;
+export declare const type: <A>(properties: { [K in keyof A]: Guard<A[K]>; }) => Guard<{ [K_1 in keyof A]: A[K_1]; }>;
 /**
@@ -79,7 +69,3 @@ * @category combinators
  */
-export declare function partial<A>(properties: {
-    [K in keyof A]: Guard<A[K]>;
-}): Guard<Partial<{
-    [K in keyof A]: A[K];
-}>>;
+export declare const partial: <A>(properties: { [K in keyof A]: Guard<A[K]>; }) => Guard<Partial<{ [K_1 in keyof A]: A[K_1]; }>>;
 /**
@@ -89,3 +75,3 @@ * @category combinators
  */
-export declare function record<A>(codomain: Guard<A>): Guard<Record<string, A>>;
+export declare const record: <A>(codomain: Guard<A>) => Guard<Record<string, A>>;
 /**
@@ -95,3 +81,3 @@ * @category combinators
  */
-export declare function array<A>(items: Guard<A>): Guard<Array<A>>;
+export declare const array: <A>(items: Guard<A>) => Guard<A[]>;
 /**
@@ -101,5 +87,3 @@ * @category combinators
  */
-export declare function tuple<A extends ReadonlyArray<unknown>>(...components: {
-    [K in keyof A]: Guard<A[K]>;
-}): Guard<A>;
+export declare const tuple: <A extends readonly unknown[]>(...components: { [K in keyof A]: Guard<A[K]>; }) => Guard<A>;
 /**
@@ -109,3 +93,3 @@ * @category combinators
  */
-export declare function intersection<A, B>(left: Guard<A>, right: Guard<B>): Guard<A & B>;
+export declare const intersect: <B>(right: Guard<B>) => <A>(left: Guard<A>) => Guard<A & B>;
 /**
@@ -115,5 +99,3 @@ * @category combinators
  */
-export declare function union<A extends ReadonlyArray<unknown>>(...members: {
-    [K in keyof A]: Guard<A[K]>;
-}): Guard<A[number]>;
+export declare const union: <A extends readonly [unknown, ...unknown[]]>(...members: { [K in keyof A]: Guard<A[K]>; }) => Guard<A[number]>;
 /**
@@ -123,5 +105,3 @@ * @category combinators
  */
-export declare function sum<T extends string>(tag: T): <A>(members: {
-    [K in keyof A]: Guard<A[K]>;
-}) => Guard<A[keyof A]>;
+export declare const sum: <T extends string>(tag: T) => <A>(members: { [K in keyof A]: Guard<A[K]>; }) => Guard<A[keyof A]>;
 /**
@@ -131,3 +111,3 @@ * @category combinators
  */
-export declare function lazy<A>(f: () => Guard<A>): Guard<A>;
+export declare const lazy: <A>(f: () => Guard<A>) => Guard<A>;
 /**
@@ -152,2 +132,2 @@ * @category instances
  */
-export declare const schemableGuard: Schemable1<URI> & WithUnknownContainers1<URI> & WithUnion1<URI> & WithRefinement1<URI>;
+export declare const schemableGuard: Schemable1<URI> & WithUnknownContainers1<URI> & WithUnion1<URI> & WithRefine1<URI>;

es6/Guard.js

 /**
+ * **This module is experimental**
+ *
+ * Experimental features are published in order to get early feedback from the community, see these tracking
+ * [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
+ *
+ * A feature tagged as _Experimental_ is in a high state of flux, you're at risk of it changing without notice.
+ *
  * @since 2.2.0
  */
+import { pipe } from 'fp-ts/es6/pipeable';
 import { memoize } from './Schemable';
@@ -12,3 +20,3 @@ // -------------------------------------------------------------------------------------
  */
-export function literal() {
+export var literal = function () {
     var values = [];
@@ -18,6 +26,6 @@ for (var _i = 0; _i < arguments.length; _i++) {
     }
-    return {
+    return ({
         is: function (u) { return values.findIndex(function (a) { return a === u; }) !== -1; }
-    };
-}
+    });
+};
 // -------------------------------------------------------------------------------------
@@ -30,9 +38,2 @@ // primitives
  */
-export var never = {
-    is: function (_u) { return false; }
-};
-/**
- * @category primitives
- * @since 2.2.0
- */
 export var string = {
@@ -42,2 +43,4 @@ is: function (u) { return typeof u === 'string'; }
 /**
+ * Note: `NaN` is excluded.
+ *
  * @category primitives
@@ -47,3 +50,3 @@ * @since 2.2.0
 export var number = {
-    is: function (u) { return typeof u === 'number'; }
+    is: function (u) { return typeof u === 'number' && !isNaN(u); }
 };
@@ -71,2 +74,8 @@ /**
 };
+/**
+ * @internal
+ */
+export var object = {
+    is: function (u) { return u != null && !string.is(u) && !number.is(u) && !boolean.is(u); }
+};
 // -------------------------------------------------------------------------------------
@@ -79,7 +88,5 @@ // combinators
  */
-export function refinement(from, refinement) {
-    return {
-        is: function (u) { return from.is(u) && refinement(u); }
-    };
-}
+export var refine = function (refinement) { return function (from) { return ({
+    is: function (u) { return from.is(u) && refinement(u); }
+}); }; };
 /**
@@ -89,7 +96,5 @@ * @category combinators
  */
-export function nullable(or) {
-    return {
-        is: function (u) { return u === null || or.is(u); }
-    };
-}
+export var nullable = function (or) { return ({
+    is: function (u) { return u === null || or.is(u); }
+}); };
 /**
@@ -99,4 +104,4 @@ * @category combinators
  */
-export function type(properties) {
-    return refinement(UnknownRecord, function (r) {
+export var type = function (properties) {
+    return pipe(UnknownRecord, refine(function (r) {
         for (var k in properties) {
@@ -108,4 +113,4 @@ if (!(k in r) || !properties[k].is(r[k])) {
         return true;
-    });
-}
+    }));
+};
 /**
@@ -115,4 +120,4 @@ * @category combinators
  */
-export function partial(properties) {
-    return refinement(UnknownRecord, function (r) {
+export var partial = function (properties) {
+    return pipe(UnknownRecord, refine(function (r) {
         for (var k in properties) {
@@ -125,4 +130,4 @@ var v = r[k];
         return true;
-    });
-}
+    }));
+};
 /**
@@ -132,4 +137,4 @@ * @category combinators
  */
-export function record(codomain) {
-    return refinement(UnknownRecord, function (r) {
+export var record = function (codomain) {
+    return pipe(UnknownRecord, refine(function (r) {
         for (var k in r) {
@@ -141,4 +146,4 @@ if (!codomain.is(r[k])) {
         return true;
-    });
-}
+    }));
+};
 /**
@@ -148,5 +153,5 @@ * @category combinators
  */
-export function array(items) {
-    return refinement(UnknownArray, function (us) { return us.every(items.is); });
-}
+export var array = function (items) {
+    return pipe(UnknownArray, refine(function (us) { return us.every(items.is); }));
+};
 /**
@@ -156,3 +161,3 @@ * @category combinators
  */
-export function tuple() {
+export var tuple = function () {
     var components = [];
@@ -162,6 +167,6 @@ for (var _i = 0; _i < arguments.length; _i++) {
     }
-    return {
+    return ({
         is: function (u) { return Array.isArray(u) && u.length === components.length && components.every(function (c, i) { return c.is(u[i]); }); }
-    };
-}
+    });
+};
 /**
@@ -171,7 +176,5 @@ * @category combinators
  */
-export function intersection(left, right) {
-    return {
-        is: function (u) { return left.is(u) && right.is(u); }
-    };
-}
+export var intersect = function (right) { return function (left) { return ({
+    is: function (u) { return left.is(u) && right.is(u); }
+}); }; };
 /**
@@ -181,3 +184,3 @@ * @category combinators
  */
-export function union() {
+export var union = function () {
     var members = [];
@@ -187,6 +190,6 @@ for (var _i = 0; _i < arguments.length; _i++) {
     }
-    return {
+    return ({
         is: function (u) { return members.some(function (m) { return m.is(u); }); }
-    };
-}
+    });
+};
 /**
@@ -196,13 +199,11 @@ * @category combinators
  */
-export function sum(tag) {
-    return function (members) {
-        return refinement(UnknownRecord, function (r) {
-            var v = r[tag];
-            if (v in members) {
-                return members[v].is(r);
-            }
-            return false;
-        });
-    };
-}
+export var sum = function (tag) { return function (members) {
+    return pipe(UnknownRecord, refine(function (r) {
+        var v = r[tag];
+        if (v in members) {
+            return members[v].is(r);
+        }
+        return false;
+    }));
+}; };
 /**
@@ -212,3 +213,3 @@ * @category combinators
  */
-export function lazy(f) {
+export var lazy = function (f) {
     var get = memoize(f);
@@ -218,3 +219,3 @@ return {
     };
-}
+};
 // -------------------------------------------------------------------------------------
@@ -244,3 +245,3 @@ // instances
     tuple: tuple,
-    intersection: intersection,
+    intersect: intersect,
     sum: sum,
@@ -251,3 +252,3 @@ lazy: function (_, f) { return lazy(f); },
     union: union,
-    refinement: refinement
+    refine: refine
 };

es6/JsonCodec.d.ts

 /**
+ * **This module is experimental**
+ *
+ * Experimental features are published in order to get early feedback from the community, see these tracking
+ * [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
+ *
+ * A feature tagged as _Experimental_ is in a high state of flux, you're at risk of it changing without notice.
+ *
  * @since 2.2.3
@@ -8,3 +15,3 @@ */
 import * as C from './Codec';
-import { Literal, Schemable1, WithRefinement1 } from './Schemable';
+import { Literal, Schemable1, WithRefine1 } from './Schemable';
 /**
@@ -34,3 +41,3 @@ * Laws:
  */
-export declare const literal: <A extends ReadonlyArray<Literal>>(...values: A) => JsonCodec<A[number]>;
+export declare const literal: <A extends readonly [Literal, ...Array<Literal>]>(...values: A) => JsonCodec<A[number]>;
 /**
@@ -55,3 +62,3 @@ * @category primitives
  */
-export declare const withExpected: <A>(codec: JsonCodec<A>, expected: (actual: unknown, e: D.DecodeError) => D.DecodeError) => JsonCodec<A>;
+export declare const mapLeftWithInput: (f: (actual: unknown, e: D.DecodeError) => D.DecodeError) => <A>(codec: JsonCodec<A>) => JsonCodec<A>;
 /**
@@ -61,3 +68,3 @@ * @category combinators
  */
-export declare const refinement: <A, B extends A>(from: JsonCodec<A>, refinement: (a: A) => a is B, expected: string) => JsonCodec<B>;
+export declare const refine: <A, B extends A>(refinement: (a: A) => a is B, id: string) => (from: JsonCodec<A>) => JsonCodec<B>;
 /**
@@ -107,3 +114,3 @@ * @category combinators
  */
-export declare const intersection: <A, B>(left: JsonCodec<A>, right: JsonCodec<B>) => JsonCodec<A & B>;
+export declare const intersect: <B>(right: JsonCodec<B>) => <A>(left: JsonCodec<A>) => JsonCodec<A & B>;
 /**
@@ -150,2 +157,2 @@ * @category combinators
  */
-export declare const schemableJsonCodec: Schemable1<URI> & WithRefinement1<URI>;
+export declare const schemableJsonCodec: Schemable1<URI> & WithRefine1<URI>;

es6/JsonCodec.js

@@ -40,3 +40,3 @@ import * as C from './Codec';
  */
-export var withExpected = C.withExpected;
+export var mapLeftWithInput = C.mapLeftWithInput;
 /**
@@ -46,3 +46,3 @@ * @category combinators
  */
-export var refinement = C.refinement;
+export var refine = C.refine;
 /**
@@ -82,3 +82,3 @@ * @category combinators
  */
-export var intersection = C.intersection;
+export var intersect = C.intersect;
 /**
@@ -134,6 +134,6 @@ * @category combinators
     tuple: tuple,
-    intersection: intersection,
+    intersect: intersect,
     sum: sum,
     lazy: lazy,
-    refinement: refinement
+    refine: refine
 };

es6/JsonEncoder.d.ts

 /**
+ * **This module is experimental**
+ *
+ * Experimental features are published in order to get early feedback from the community, see these tracking
+ * [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
+ *
+ * A feature tagged as _Experimental_ is in a high state of flux, you're at risk of it changing without notice.
+ *
  * @since 2.2.3
@@ -11,3 +18,3 @@ */
  */
-export interface JsonArray extends Array<Json> {
+export interface JsonArray extends ReadonlyArray<Json> {
 }
@@ -18,5 +25,5 @@ /**
  */
-export declare type JsonObject = {
-    [key: string]: Json;
-};
+export interface JsonRecord {
+    readonly [key: string]: Json;
+}
 /**
@@ -26,3 +33,3 @@ * @category model
  */
-export declare type Json = null | string | number | boolean | JsonObject | JsonArray;
+export declare type Json = null | string | number | boolean | JsonRecord | JsonArray;
 /**
@@ -88,3 +95,3 @@ * @category model
  */
-export declare const intersection: <A, B>(left: JsonEncoder<A>, right: JsonEncoder<B>) => JsonEncoder<A & B>;
+export declare const intersect: <B>(right: JsonEncoder<B>) => <A>(left: JsonEncoder<A>) => JsonEncoder<A & B>;
 /**
@@ -91,0 +98,0 @@ * @category combinators

es6/JsonEncoder.js

@@ -52,3 +52,3 @@ import { identity } from 'fp-ts/es6/function';
  */
-export var intersection = E.intersection;
+export var intersect = E.intersect;
 /**
@@ -104,5 +104,5 @@ * @category combinators
     tuple: tuple,
-    intersection: intersection,
+    intersect: intersect,
     sum: sum,
     lazy: function (_, f) { return lazy(f); }
 };

es6/Schema.d.ts

 /**
+ * **This module is experimental**
+ *
+ * Experimental features are published in order to get early feedback from the community, see these tracking
+ * [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
+ *
+ * A feature tagged as _Experimental_ is in a high state of flux, you're at risk of it changing without notice.
+ *
  * @since 2.2.0
@@ -3,0 +10,0 @@ */

es6/Schemable.d.ts

 /**
+ * **This module is experimental**
+ *
+ * Experimental features are published in order to get early feedback from the community, see these tracking
+ * [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
+ *
+ * A feature tagged as _Experimental_ is in a high state of flux, you're at risk of it changing without notice.
+ *
  * @since 2.2.0
@@ -14,3 +21,3 @@ */
     readonly URI: S;
-    readonly literal: <A extends ReadonlyArray<Literal>>(...values: A) => HKT<S, A[number]>;
+    readonly literal: <A extends readonly [Literal, ...Array<Literal>]>(...values: A) => HKT<S, A[number]>;
     readonly string: HKT<S, string>;
@@ -35,3 +42,3 @@ readonly number: HKT<S, number>;
     }) => HKT<S, A>;
-    readonly intersection: <A, B>(left: HKT<S, A>, right: HKT<S, B>) => HKT<S, A & B>;
+    readonly intersect: <B>(right: HKT<S, B>) => <A>(left: HKT<S, A>) => HKT<S, A & B>;
     readonly sum: <T extends string>(tag: T) => <A>(members: {
@@ -47,3 +54,3 @@ [K in keyof A]: HKT<S, A[K]>;
     readonly URI: S;
-    readonly literal: <A extends ReadonlyArray<Literal>>(...values: A) => Kind<S, A[number]>;
+    readonly literal: <A extends readonly [Literal, ...Array<Literal>]>(...values: A) => Kind<S, A[number]>;
     readonly string: Kind<S, string>;
@@ -68,3 +75,3 @@ readonly number: Kind<S, number>;
     }) => Kind<S, A>;
-    readonly intersection: <A, B>(left: Kind<S, A>, right: Kind<S, B>) => Kind<S, A & B>;
+    readonly intersect: <B>(right: Kind<S, B>) => <A>(left: Kind<S, A>) => Kind<S, A & B>;
     readonly sum: <T extends string>(tag: T) => <A>(members: {
@@ -93,3 +100,3 @@ [K in keyof A]: Kind<S, A[K]>;
 export interface WithUnion<S> {
-    readonly union: <A extends ReadonlyArray<unknown>>(...members: {
+    readonly union: <A extends readonly [unknown, ...Array<unknown>]>(...members: {
         [K in keyof A]: HKT<S, A[K]>;
@@ -102,3 +109,3 @@ }) => HKT<S, A[number]>;
 export interface WithUnion1<S extends URIS> {
-    readonly union: <A extends ReadonlyArray<unknown>>(...members: {
+    readonly union: <A extends readonly [unknown, ...Array<unknown>]>(...members: {
         [K in keyof A]: Kind<S, A[K]>;
@@ -110,4 +117,4 @@ }) => Kind<S, A[number]>;
  */
-export interface WithRefinement<S> {
-    readonly refinement: <A, B extends A>(from: HKT<S, A>, refinement: (a: A) => a is B, expected: string) => HKT<S, B>;
+export interface WithRefine<S> {
+    readonly refine: <A, B extends A>(refinement: (a: A) => a is B, id: string) => (from: HKT<S, A>) => HKT<S, B>;
 }
@@ -117,4 +124,4 @@ /**
  */
-export interface WithRefinement1<S extends URIS> {
-    readonly refinement: <A, B extends A>(from: Kind<S, A>, refinement: (a: A) => a is B, expected: string) => Kind<S, B>;
+export interface WithRefine1<S extends URIS> {
+    readonly refine: <A, B extends A>(refinement: (a: A) => a is B, id: string) => (from: Kind<S, A>) => Kind<S, B>;
 }
@@ -121,0 +128,0 @@ /**

es6/Schemable.js

@@ -15,1 +15,18 @@ /**
 }
+// -------------------------------------------------------------------------------------
+// utils
+// -------------------------------------------------------------------------------------
+var typeOf = function (x) { return (x === null ? 'null' : typeof x); };
+/**
+ * @internal
+ */
+export var intersect_ = function (a, b) {
+    if (a !== undefined && b !== undefined) {
+        var tx = typeOf(a);
+        var ty = typeOf(b);
+        if (tx === 'object' || ty === 'object') {
+            return Object.assign({}, a, b);
+        }
+    }
+    return b;
+};

es6/Type.d.ts

 /**
+ * **This module is experimental**
+ *
+ * Experimental features are published in order to get early feedback from the community, see these tracking
+ * [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
+ *
+ * A feature tagged as _Experimental_ is in a high state of flux, you're at risk of it changing without notice.
+ *
  * @since 2.2.3
  */
 import * as t from './index';
-import { Literal, Schemable1, WithUnion1, WithRefinement1, WithUnknownContainers1 } from './Schemable';
+import { Literal, Schemable1, WithUnion1, WithRefine1, WithUnknownContainers1 } from './Schemable';
 /**
@@ -16,3 +23,3 @@ * @category model
  */
-export declare function literal<A extends ReadonlyArray<Literal>>(...values: A): Type<A[number]>;
+export declare const literal: <A extends readonly [Literal, ...Literal[]]>(...values: A) => Type<A[number]>;
 /**
@@ -47,3 +54,3 @@ * @category primitives
  */
-export declare function refinement<A, B extends A>(from: Type<A>, refinement: (a: A) => a is B, expected: string): Type<B>;
+export declare const refine: <A, B extends A>(refinement: (a: A) => a is B, id: string) => (from: Type<A>) => Type<B>;
 /**
@@ -53,3 +60,3 @@ * @category combinators
  */
-export declare function nullable<A>(or: Type<A>): Type<null | A>;
+export declare const nullable: <A>(or: Type<A>) => Type<A | null>;
 /**
@@ -59,7 +66,3 @@ * @category combinators
  */
-export declare function type<A>(properties: {
-    [K in keyof A]: Type<A[K]>;
-}): Type<{
-    [K in keyof A]: A[K];
-}>;
+export declare const type: <A>(properties: { [K in keyof A]: Type<A[K]>; }) => Type<{ [K_1 in keyof A]: A[K_1]; }>;
 /**
@@ -69,7 +72,3 @@ * @category combinators
  */
-export declare function partial<A>(properties: {
-    [K in keyof A]: Type<A[K]>;
-}): Type<Partial<{
-    [K in keyof A]: A[K];
-}>>;
+export declare const partial: <A>(properties: { [K in keyof A]: Type<A[K]>; }) => Type<Partial<{ [K_1 in keyof A]: A[K_1]; }>>;
 /**
@@ -79,3 +78,3 @@ * @category combinators
  */
-export declare function record<A>(codomain: Type<A>): Type<Record<string, A>>;
+export declare const record: <A>(codomain: Type<A>) => Type<Record<string, A>>;
 /**
@@ -85,3 +84,3 @@ * @category combinators
  */
-export declare function array<A>(items: Type<A>): Type<Array<A>>;
+export declare const array: <A>(items: Type<A>) => Type<A[]>;
 /**
@@ -91,5 +90,3 @@ * @category combinators
  */
-export declare function tuple<A extends ReadonlyArray<unknown>>(...components: {
-    [K in keyof A]: Type<A[K]>;
-}): Type<A>;
+export declare const tuple: <A extends readonly unknown[]>(...components: { [K in keyof A]: Type<A[K]>; }) => Type<A>;
 /**
@@ -99,3 +96,3 @@ * @category combinators
  */
-export declare function intersection<A, B>(left: Type<A>, right: Type<B>): Type<A & B>;
+export declare const intersect: <B>(right: Type<B>) => <A>(left: Type<A>) => Type<A & B>;
 /**
@@ -105,3 +102,3 @@ * @category combinators
  */
-export declare function lazy<A>(id: string, f: () => Type<A>): Type<A>;
+export declare const lazy: <A>(id: string, f: () => Type<A>) => Type<A>;
 /**
@@ -111,5 +108,3 @@ * @category combinators
  */
-export declare function sum<T extends string>(_tag: T): <A>(members: {
-    [K in keyof A]: Type<A[K]>;
-}) => Type<A[keyof A]>;
+export declare const sum: <T extends string>(_tag: T) => <A>(members: { [K in keyof A]: Type<A[K]>; }) => Type<A[keyof A]>;
 /**
@@ -119,5 +114,3 @@ * @category combinators
  */
-export declare function union<A extends ReadonlyArray<unknown>>(...members: {
-    [K in keyof A]: Type<A[K]>;
-}): Type<A[number]>;
+export declare const union: <A extends readonly [unknown, ...unknown[]]>(...members: { [K in keyof A]: Type<A[K]>; }) => Type<A[number]>;
 /**
@@ -142,2 +135,2 @@ * @category instances
  */
-export declare const schemableType: Schemable1<URI> & WithUnknownContainers1<URI> & WithUnion1<URI> & WithRefinement1<URI>;
+export declare const schemableType: Schemable1<URI> & WithUnknownContainers1<URI> & WithUnion1<URI> & WithRefine1<URI>;

es6/Type.js

 /**
+ * **This module is experimental**
+ *
+ * Experimental features are published in order to get early feedback from the community, see these tracking
+ * [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
+ *
+ * A feature tagged as _Experimental_ is in a high state of flux, you're at risk of it changing without notice.
+ *
  * @since 2.2.3
  */
 import * as t from './index';
+import * as E from 'fp-ts/es6/Either';
+import { pipe } from 'fp-ts/es6/pipeable';
 // -------------------------------------------------------------------------------------
@@ -12,3 +21,3 @@ // constructors
  */
-export function literal() {
+export var literal = function () {
     var values = [];
@@ -19,3 +28,3 @@ for (var _i = 0; _i < arguments.length; _i++) {
     return t.union(values.map(function (v) { return t.literal(v); }));
-}
+};
 // -------------------------------------------------------------------------------------
@@ -33,3 +42,5 @@ // primitives
  */
-export var number = t.number;
+export var number = new t.Type(t.number.name, t.number.is, function (u, c) {
+    return pipe(t.number.decode(u), E.chain(function (n) { return (isNaN(n) ? t.failure(u, c) : t.success(n)); }));
+}, t.number.encode);
 /**
@@ -57,6 +68,6 @@ * @category primitives
  */
-export function refinement(from, refinement, expected) {
+export var refine = function (refinement, id) { return function (from) {
     // tslint:disable-next-line: deprecation
-    return t.refinement(from, refinement, expected);
-}
+    return t.refinement(from, refinement, id);
+}; };
 /**
@@ -66,5 +77,3 @@ * @category combinators
  */
-export function nullable(or) {
-    return t.union([t.null, or]);
-}
+export var nullable = function (or) { return t.union([t.null, or]); };
 /**
@@ -74,5 +83,5 @@ * @category combinators
  */
-export function type(properties) {
+export var type = function (properties) {
     return t.type(properties);
-}
+};
 /**
@@ -82,5 +91,5 @@ * @category combinators
  */
-export function partial(properties) {
+export var partial = function (properties) {
     return t.partial(properties);
-}
+};
 /**
@@ -90,5 +99,3 @@ * @category combinators
  */
-export function record(codomain) {
-    return t.record(t.string, codomain);
-}
+export var record = function (codomain) { return t.record(t.string, codomain); };
 /**
@@ -98,5 +105,3 @@ * @category combinators
  */
-export function array(items) {
-    return t.array(items);
-}
+export var array = function (items) { return t.array(items); };
 /**
@@ -106,3 +111,3 @@ * @category combinators
  */
-export function tuple() {
+export var tuple = function () {
     var components = [];
@@ -113,3 +118,3 @@ for (var _i = 0; _i < arguments.length; _i++) {
     return t.tuple(components);
-}
+};
 /**
@@ -119,5 +124,3 @@ * @category combinators
  */
-export function intersection(left, right) {
-    return t.intersection([left, right]);
-}
+export var intersect = function (right) { return function (left) { return t.intersection([left, right]); }; };
 /**
@@ -127,5 +130,3 @@ * @category combinators
  */
-export function lazy(id, f) {
-    return t.recursion(id, f);
-}
+export var lazy = function (id, f) { return t.recursion(id, f); };
 /**
@@ -135,5 +136,5 @@ * @category combinators
  */
-export function sum(_tag) {
-    return function (members) { return t.union(Object.values(members)); };
-}
+export var sum = function (_tag) { return function (members) {
+    return t.union(Object.values(members));
+}; };
 /**
@@ -143,3 +144,3 @@ * @category combinators
  */
-export function union() {
+export var union = function () {
     var members = [];
@@ -150,3 +151,3 @@ for (var _i = 0; _i < arguments.length; _i++) {
     return t.union(members);
-}
+};
 // -------------------------------------------------------------------------------------
@@ -176,3 +177,3 @@ // instances
     tuple: tuple,
-    intersection: intersection,
+    intersect: intersect,
     sum: sum,
@@ -183,3 +184,3 @@ lazy: lazy,
     union: union,
-    refinement: refinement
+    refine: refine
 };

lib/Codec.d.ts

 /**
+ * **This module is experimental**
+ *
+ * Experimental features are published in order to get early feedback from the community, see these tracking
+ * [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
+ *
+ * A feature tagged as _Experimental_ is in a high state of flux, you're at risk of it changing without notice.
+ *
  * @since 2.2.3
@@ -41,3 +48,3 @@ */
  */
-export declare function literal<A extends ReadonlyArray<Literal>>(...values: A): Codec<A[number], A[number]>;
+export declare function literal<A extends readonly [Literal, ...Array<Literal>]>(...values: A): Codec<A[number], A[number]>;
 /**
@@ -72,3 +79,3 @@ * @category primitives
  */
-export declare function withExpected<O, A>(codec: Codec<O, A>, expected: (actual: unknown, e: D.DecodeError) => D.DecodeError): Codec<O, A>;
+export declare const mapLeftWithInput: (f: (actual: unknown, e: D.DecodeError) => D.DecodeError) => <O, A>(codec: Codec<O, A>) => Codec<O, A>;
 /**
@@ -78,3 +85,3 @@ * @category combinators
  */
-export declare function refinement<O, A, B extends A>(from: Codec<O, A>, refinement: (a: A) => a is B, expected: string): Codec<O, B>;
+export declare const refine: <A, B extends A>(refinement: (a: A) => a is B, id: string) => <O>(from: Codec<O, A>) => Codec<O, B>;
 /**
@@ -126,3 +133,3 @@ * @category combinators
  */
-export declare function intersection<O, A, P, B>(left: Codec<O, A>, right: Codec<P, B>): Codec<O & P, A & B>;
+export declare const intersect: <P, B>(right: Codec<P, B>) => <O, A>(left: Codec<O, A>) => Codec<O & P, A & B>;
 /**
@@ -129,0 +136,0 @@ * @category combinators

lib/Codec.js

 "use strict";
 Object.defineProperty(exports, "__esModule", { value: true });
-exports.invariantCodec = exports.URI = exports.imap = exports.lazy = exports.sum = exports.intersection = exports.tuple = exports.array = exports.record = exports.partial = exports.type = exports.nullable = exports.refinement = exports.withExpected = exports.UnknownRecord = exports.UnknownArray = exports.boolean = exports.number = exports.string = exports.literal = exports.fromDecoder = exports.make = void 0;
+exports.invariantCodec = exports.URI = exports.imap = exports.lazy = exports.sum = exports.intersect = exports.tuple = exports.array = exports.record = exports.partial = exports.type = exports.nullable = exports.refine = exports.mapLeftWithInput = exports.UnknownRecord = exports.UnknownArray = exports.boolean = exports.number = exports.string = exports.literal = exports.fromDecoder = exports.make = void 0;
 var D = require("./Decoder");
 var E = require("./Encoder");
 var function_1 = require("fp-ts/lib/function");
+var pipeable_1 = require("fp-ts/lib/pipeable");
 // -------------------------------------------------------------------------------------
@@ -79,6 +80,3 @@ // constructors
  */
-function withExpected(codec, expected) {
-    return make(D.withExpected(codec, expected), codec);
-}
-exports.withExpected = withExpected;
+exports.mapLeftWithInput = function (f) { return function (codec) { return make(pipeable_1.pipe(codec, D.mapLeftWithInput(f)), codec); }; };
 /**
@@ -88,6 +86,6 @@ * @category combinators
  */
-function refinement(from, refinement, expected) {
-    return make(D.refinement(from, refinement, expected), from);
-}
-exports.refinement = refinement;
+exports.refine = function (refinement, id) {
+    var refine = D.refine(refinement, id);
+    return function (from) { return make(refine(from), from); };
+};
 /**
@@ -154,6 +152,7 @@ * @category combinators
  */
-function intersection(left, right) {
-    return make(D.intersection(left, right), E.intersection(left, right));
-}
-exports.intersection = intersection;
+exports.intersect = function (right) {
+    var intersectD = D.intersect(right);
+    var intersectE = E.intersect(right);
+    return function (left) { return make(intersectD(left), intersectE(left)); };
+};
 /**
@@ -160,0 +159,0 @@ * @category combinators

lib/Decoder.d.ts

 /**
- * @since 2.2.0
+ * **This module is experimental**
+ *
+ * Experimental features are published in order to get early feedback from the community, see these tracking
+ * [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
+ *
+ * A feature tagged as _Experimental_ is in a high state of flux, you're at risk of it changing without notice.
+ *
+ * @since 2.2.7
  */
+import { Alt1 } from 'fp-ts/lib/Alt';
 import * as E from 'fp-ts/lib/Either';
-import { NonEmptyArray } from 'fp-ts/lib/NonEmptyArray';
-import { Forest, Tree } from 'fp-ts/lib/Tree';
+import { Functor1 } from 'fp-ts/lib/Functor';
 import * as G from './Guard';
-import { Literal, Schemable1, WithRefinement1, WithUnion1, WithUnknownContainers1 } from './Schemable';
-import { Functor1 } from 'fp-ts/lib/Functor';
-import { Alt1 } from 'fp-ts/lib/Alt';
-import Either = E.Either;
+import * as KD from './KleisliDecoder';
+import { Literal, Schemable1, WithRefine1, WithUnion1, WithUnknownContainers1 } from './Schemable';
 /**
  * @category model
- * @since 2.2.0
+ * @since 2.2.7
  */
-export interface Decoder<A> {
-    readonly decode: (u: unknown) => Either<DecodeError, A>;
+export interface Decoder<A> extends KD.KleisliDecoder<unknown, A> {
 }
 /**
- * @since 2.2.0
- */
-export declare type TypeOf<D> = D extends Decoder<infer A> ? A : never;
-/**
  * @category DecodeError
- * @since 2.2.2
+ * @since 2.2.7
  */
-export interface DecodeError extends NonEmptyArray<Tree<string>> {
-}
+export declare type DecodeError = KD.DecodeError;
 /**
  * @category DecodeError
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function tree<A>(value: A, forest?: Forest<A>): Tree<A>;
+export declare const error: (actual: unknown, message: string) => DecodeError;
 /**
  * @category DecodeError
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function success<A>(a: A): Either<DecodeError, A>;
+export declare const success: <A>(a: A) => E.Either<DecodeError, A>;
 /**
  * @category DecodeError
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function failure<A = never>(message: string): Either<DecodeError, A>;
+export declare const failure: <A = never>(actual: unknown, message: string) => E.Either<DecodeError, A>;
 /**
- * @category DecodeError
- * @since 2.2.2
- */
-export declare function isNotEmpty<A>(as: ReadonlyArray<A>): as is NonEmptyArray<A>;
-/**
  * @category constructors
- * @since 2.2.3
+ * @since 2.2.7
  */
-export declare function of<A>(a: A): Decoder<A>;
+export declare const fromGuard: <A>(guard: G.Guard<A>, expected: string) => Decoder<A>;
 /**
  * @category constructors
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function fromGuard<A>(guard: G.Guard<A>, expected: string): Decoder<A>;
+export declare const literal: <A extends readonly [Literal, ...Array<Literal>]>(...values: A) => Decoder<A[number]>;
 /**
- * @category constructors
- * @since 2.2.0
- */
-export declare function literal<A extends ReadonlyArray<Literal>>(...values: A): Decoder<A[number]>;
-/**
  * @category primitives
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare const never: Decoder<never>;
-/**
- * @category primitives
- * @since 2.2.0
- */
 export declare const string: Decoder<string>;
 /**
  * @category primitives
- * @since 2.2.0
+ * @since 2.2.7
  */
@@ -81,3 +65,3 @@ export declare const number: Decoder<number>;
  * @category primitives
- * @since 2.2.0
+ * @since 2.2.7
  */
@@ -87,3 +71,3 @@ export declare const boolean: Decoder<boolean>;
  * @category primitives
- * @since 2.2.0
+ * @since 2.2.7
  */
@@ -93,3 +77,3 @@ export declare const UnknownArray: Decoder<Array<unknown>>;
  * @category primitives
- * @since 2.2.0
+ * @since 2.2.7
  */
@@ -99,82 +83,75 @@ export declare const UnknownRecord: Decoder<Record<string, unknown>>;
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function withExpected<A>(decoder: Decoder<A>, expected: (actual: unknown, e: DecodeError) => DecodeError): Decoder<A>;
+export declare const mapLeftWithInput: (f: (input: unknown, e: DecodeError) => DecodeError) => <A>(decoder: Decoder<A>) => Decoder<A>;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function refinement<A, B extends A>(from: Decoder<A>, refinement: (a: A) => a is B, expected: string): Decoder<B>;
+export declare const refine: <A, B extends A>(refinement: (a: A) => a is B, id: string) => (from: Decoder<A>) => Decoder<B>;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function parse<A, B>(from: Decoder<A>, parser: (a: A) => Either<string, B>): Decoder<B>;
+export declare const parse: <A, B>(parser: (a: A) => E.Either<DecodeError, B>) => (from: Decoder<A>) => Decoder<B>;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function nullable<A>(or: Decoder<A>): Decoder<null | A>;
+export declare const nullable: <A>(or: Decoder<A>) => Decoder<null | A>;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function type<A>(properties: {
-    [K in keyof A]: Decoder<A[K]>;
-}): Decoder<{
-    [K in keyof A]: A[K];
-}>;
+export declare const type: <A>(properties: { [K in keyof A]: Decoder<A[K]>; }) => Decoder<{ [K_1 in keyof A]: A[K_1]; }>;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function partial<A>(properties: {
-    [K in keyof A]: Decoder<A[K]>;
-}): Decoder<Partial<{
-    [K in keyof A]: A[K];
-}>>;
+export declare const partial: <A>(properties: { [K in keyof A]: Decoder<A[K]>; }) => Decoder<Partial<{ [K_1 in keyof A]: A[K_1]; }>>;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function record<A>(codomain: Decoder<A>): Decoder<Record<string, A>>;
+export declare const array: <A>(items: Decoder<A>) => Decoder<A[]>;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function array<A>(items: Decoder<A>): Decoder<Array<A>>;
+export declare const record: <A>(codomain: Decoder<A>) => Decoder<Record<string, A>>;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function tuple<A extends ReadonlyArray<unknown>>(...components: {
+export declare const tuple: <A extends readonly unknown[]>(...components: { [K in keyof A]: Decoder<A[K]>; }) => Decoder<A>;
+/**
+ * @category combinators
+ * @since 2.2.7
+ */
+export declare const union: <A extends readonly [unknown, ...Array<unknown>]>(...members: {
     [K in keyof A]: Decoder<A[K]>;
-}): Decoder<A>;
+}) => Decoder<A[number]>;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function intersection<A, B>(left: Decoder<A>, right: Decoder<B>): Decoder<A & B>;
+export declare const intersect: <B>(right: Decoder<B>) => <A>(left: Decoder<A>) => Decoder<A & B>;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function lazy<A>(id: string, f: () => Decoder<A>): Decoder<A>;
+export declare const sum: <T extends string>(tag: T) => <A>(members: { [K in keyof A]: Decoder<A[K]>; }) => Decoder<A[keyof A]>;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function sum<T extends string>(tag: T): <A>(members: {
-    [K in keyof A]: Decoder<A[K]>;
-}) => Decoder<A[keyof A]>;
+export declare const lazy: <A>(id: string, f: () => Decoder<A>) => Decoder<A>;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare function union<A extends ReadonlyArray<unknown>>(...members: {
-    [K in keyof A]: Decoder<A[K]>;
-}): Decoder<A[number]>;
+export declare const compose: <A, B>(to: KD.KleisliDecoder<A, B>) => (from: Decoder<A>) => Decoder<B>;
 /**
  * @category Functor
- * @since 2.2.0
+ * @since 2.2.7
  */
@@ -184,8 +161,8 @@ export declare const map: <A, B>(f: (a: A) => B) => (fa: Decoder<A>) => Decoder<B>;
  * @category Alt
- * @since 2.2.0
+ * @since 2.2.7
  */
-export declare const alt: <A>(that: () => Decoder<A>) => (fa: Decoder<A>) => Decoder<A>;
+export declare const alt: <A>(that: () => Decoder<A>) => (me: Decoder<A>) => Decoder<A>;
 /**
  * @category instances
- * @since 2.2.0
+ * @since 2.2.7
  */
@@ -195,3 +172,3 @@ export declare const URI = "io-ts/Decoder";
  * @category instances
- * @since 2.2.0
+ * @since 2.2.7
  */
@@ -206,3 +183,3 @@ export declare type URI = typeof URI;
  * @category instances
- * @since 2.2.3
+ * @since 2.2.7
  */
@@ -212,3 +189,3 @@ export declare const functorDecoder: Functor1<URI>;
  * @category instances
- * @since 2.2.3
+ * @since 2.2.7
  */
@@ -218,4 +195,12 @@ export declare const altDecoder: Alt1<URI>;
  * @category instances
- * @since 2.2.3
+ * @since 2.2.7
  */
-export declare const schemableDecoder: Schemable1<URI> & WithUnknownContainers1<URI> & WithUnion1<URI> & WithRefinement1<URI>;
+export declare const schemableDecoder: Schemable1<URI> & WithUnknownContainers1<URI> & WithUnion1<URI> & WithRefine1<URI>;
+/**
+ * @since 2.2.7
+ */
+export declare type TypeOf<D> = KD.TypeOf<D>;
+/**
+ * @since 2.2.7
+ */
+export declare const draw: (e: DecodeError) => string;

lib/Decoder.js

 "use strict";
 Object.defineProperty(exports, "__esModule", { value: true });
-exports.schemableDecoder = exports.altDecoder = exports.functorDecoder = exports.URI = exports.alt = exports.map = exports.union = exports.sum = exports.lazy = exports.intersection = exports.intersect = exports.tuple = exports.array = exports.record = exports.partial = exports.type = exports.nullable = exports.parse = exports.refinement = exports.withExpected = exports.UnknownRecord = exports.UnknownArray = exports.boolean = exports.number = exports.string = exports.never = exports.literal = exports.fromGuard = exports.of = exports.isNotEmpty = exports.failure = exports.success = exports.tree = void 0;
-/**
- * @since 2.2.0
- */
+exports.stringify = exports.draw = exports.schemableDecoder = exports.altDecoder = exports.functorDecoder = exports.URI = exports.alt = exports.map = exports.compose = exports.lazy = exports.sum = exports.intersect = exports.union = exports.tuple = exports.record = exports.array = exports.partial = exports.type = exports.nullable = exports.parse = exports.refine = exports.mapLeftWithInput = exports.object = exports.UnknownRecord = exports.UnknownArray = exports.boolean = exports.number = exports.string = exports.literal = exports.fromGuard = exports.failure = exports.success = exports.error = void 0;
 var E = require("fp-ts/lib/Either");
 var pipeable_1 = require("fp-ts/lib/pipeable");
+var DE = require("./DecodeError");
+var FS = require("./FreeSemigroup");
 var G = require("./Guard");
-var Schemable_1 = require("./Schemable");
-var empty = [];
+var KD = require("./KleisliDecoder");
 /**
  * @category DecodeError
- * @since 2.2.0
+ * @since 2.2.7
  */
-function tree(value, forest) {
-    if (forest === void 0) { forest = empty; }
-    return {
-        value: value,
-        forest: forest
-    };
-}
-exports.tree = tree;
+exports.error = KD.error;
 /**
  * @category DecodeError
- * @since 2.2.0
+ * @since 2.2.7
  */
-function success(a) {
-    return E.right(a);
-}
-exports.success = success;
+exports.success = KD.success;
 /**
  * @category DecodeError
- * @since 2.2.0
+ * @since 2.2.7
  */
-function failure(message) {
-    return E.left([tree(message)]);
-}
-exports.failure = failure;
-/**
- * @category DecodeError
- * @since 2.2.2
- */
-function isNotEmpty(as) {
-    return as.length > 0;
-}
-exports.isNotEmpty = isNotEmpty;
+exports.failure = KD.failure;
 // -------------------------------------------------------------------------------------
@@ -53,37 +30,10 @@ // constructors
  * @category constructors
- * @since 2.2.3
+ * @since 2.2.7
  */
-function of(a) {
-    return {
-        decode: function () { return success(a); }
-    };
-}
-exports.of = of;
+exports.fromGuard = function (guard, expected) { return KD.fromRefinement(guard.is, expected); };
 /**
  * @category constructors
- * @since 2.2.0
+ * @since 2.2.7
  */
-function fromGuard(guard, expected) {
-    return {
-        decode: function (u) { return (guard.is(u) ? success(u) : failure("cannot decode " + JSON.stringify(u) + ", should be " + expected)); }
-    };
-}
-exports.fromGuard = fromGuard;
-/**
- * @category constructors
- * @since 2.2.0
- */
-function literal() {
-    var _a;
-    var values = [];
-    for (var _i = 0; _i < arguments.length; _i++) {
-        values[_i] = arguments[_i];
-    }
-    if (values.length === 0) {
-        return exports.never;
-    }
-    var expected = values.map(function (value) { return JSON.stringify(value); }).join(' | ');
-    return fromGuard((_a = G.schemableGuard).literal.apply(_a, values), expected);
-}
-exports.literal = literal;
+exports.literal = KD.literal;
 // -------------------------------------------------------------------------------------
@@ -94,30 +44,41 @@ // primitives
  * @category primitives
- * @since 2.2.0
+ * @since 2.2.7
  */
-exports.never = fromGuard(G.never, 'never');
+exports.string = 
+/*#__PURE__*/
+exports.fromGuard(G.string, 'string');
 /**
  * @category primitives
- * @since 2.2.0
+ * @since 2.2.7
  */
-exports.string = fromGuard(G.string, 'string');
+exports.number = 
+/*#__PURE__*/
+exports.fromGuard(G.number, 'number');
 /**
  * @category primitives
- * @since 2.2.0
+ * @since 2.2.7
  */
-exports.number = fromGuard(G.number, 'number');
+exports.boolean = 
+/*#__PURE__*/
+exports.fromGuard(G.boolean, 'boolean');
 /**
  * @category primitives
- * @since 2.2.0
+ * @since 2.2.7
  */
-exports.boolean = fromGuard(G.boolean, 'boolean');
+exports.UnknownArray = 
+/*#__PURE__*/
+exports.fromGuard(G.UnknownArray, 'Array<unknown>');
 /**
  * @category primitives
- * @since 2.2.0
+ * @since 2.2.7
  */
-exports.UnknownArray = fromGuard(G.UnknownArray, 'Array<unknown>');
+exports.UnknownRecord = 
+/*#__PURE__*/
+exports.fromGuard(G.UnknownRecord, 'Record<string, unknown>');
 /**
- * @category primitives
- * @since 2.2.0
+ * @internal
  */
-exports.UnknownRecord = fromGuard(G.UnknownRecord, 'Record<string, unknown>');
+exports.object = 
+/*#__PURE__*/
+exports.fromGuard(G.object, 'object');
 // -------------------------------------------------------------------------------------
@@ -128,193 +89,51 @@ // combinators
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-function withExpected(decoder, expected) {
-    return {
-        decode: function (u) {
-            return pipeable_1.pipe(decoder.decode(u), E.mapLeft(function (nea) { return expected(u, nea); }));
-        }
-    };
-}
-exports.withExpected = withExpected;
+exports.mapLeftWithInput = KD.mapLeftWithInput;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-function refinement(from, refinement, expected) {
-    return {
-        decode: function (u) {
-            var e = from.decode(u);
-            if (E.isLeft(e)) {
-                return e;
-            }
-            var a = e.right;
-            return refinement(a) ? success(a) : failure("cannot refine " + JSON.stringify(u) + ", should be " + expected);
-        }
-    };
-}
-exports.refinement = refinement;
+exports.refine = KD.refine;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-function parse(from, parser) {
-    return {
-        decode: function (u) {
-            var e = from.decode(u);
-            if (E.isLeft(e)) {
-                return e;
-            }
-            var pe = parser(e.right);
-            if (E.isLeft(pe)) {
-                return failure(pe.left);
-            }
-            return pe;
-        }
-    };
-}
-exports.parse = parse;
+exports.parse = KD.parse;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-function nullable(or) {
-    return union(literal(null), or);
-}
-exports.nullable = nullable;
+exports.nullable = KD.nullable;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-function type(properties) {
-    return {
-        decode: function (u) {
-            var e = exports.UnknownRecord.decode(u);
-            if (E.isLeft(e)) {
-                return e;
-            }
-            else {
-                var r = e.right;
-                var a = {};
-                var errors = [];
-                for (var k in properties) {
-                    var e_1 = properties[k].decode(r[k]);
-                    if (E.isLeft(e_1)) {
-                        errors.push(tree("required property " + JSON.stringify(k), e_1.left));
-                    }
-                    else {
-                        a[k] = e_1.right;
-                    }
-                }
-                return isNotEmpty(errors) ? E.left(errors) : success(a);
-            }
-        }
-    };
-}
-exports.type = type;
+exports.type = function (properties) {
+    return pipeable_1.pipe(exports.object, exports.compose(KD.type(properties)));
+};
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-function partial(properties) {
-    return {
-        decode: function (u) {
-            var e = exports.UnknownRecord.decode(u);
-            if (E.isLeft(e)) {
-                return e;
-            }
-            else {
-                var r = e.right;
-                var a = {};
-                var errors = [];
-                for (var k in properties) {
-                    // don't add missing properties
-                    if (k in r) {
-                        var rk = r[k];
-                        // don't strip undefined properties
-                        if (rk === undefined) {
-                            a[k] = undefined;
-                        }
-                        else {
-                            var e_2 = properties[k].decode(rk);
-                            if (E.isLeft(e_2)) {
-                                errors.push(tree("optional property " + JSON.stringify(k), e_2.left));
-                            }
-                            else {
-                                a[k] = e_2.right;
-                            }
-                        }
-                    }
-                }
-                return isNotEmpty(errors) ? E.left(errors) : success(a);
-            }
-        }
-    };
-}
-exports.partial = partial;
+exports.partial = function (properties) {
+    return pipeable_1.pipe(exports.object, exports.compose(KD.partial(properties)));
+};
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-function record(codomain) {
-    return {
-        decode: function (u) {
-            var e = exports.UnknownRecord.decode(u);
-            if (E.isLeft(e)) {
-                return e;
-            }
-            else {
-                var r = e.right;
-                var a = {};
-                var errors = [];
-                for (var k in r) {
-                    var e_3 = codomain.decode(r[k]);
-                    if (E.isLeft(e_3)) {
-                        errors.push(tree("key " + JSON.stringify(k), e_3.left));
-                    }
-                    else {
-                        a[k] = e_3.right;
-                    }
-                }
-                return isNotEmpty(errors) ? E.left(errors) : success(a);
-            }
-        }
-    };
-}
-exports.record = record;
+exports.array = function (items) { return pipeable_1.pipe(exports.UnknownArray, exports.compose(KD.array(items))); };
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-function array(items) {
-    return {
-        decode: function (u) {
-            var e = exports.UnknownArray.decode(u);
-            if (E.isLeft(e)) {
-                return e;
-            }
-            else {
-                var us = e.right;
-                var len = us.length;
-                var a = new Array(len);
-                var errors = [];
-                for (var i = 0; i < len; i++) {
-                    var e_4 = items.decode(us[i]);
-                    if (E.isLeft(e_4)) {
-                        errors.push(tree("item " + i, e_4.left));
-                    }
-                    else {
-                        a[i] = e_4.right;
-                    }
-                }
-                return isNotEmpty(errors) ? E.left(errors) : success(a);
-            }
-        }
-    };
-}
-exports.array = array;
+exports.record = function (codomain) {
+    return pipeable_1.pipe(exports.UnknownRecord, exports.compose(KD.record(codomain)));
+};
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-function tuple() {
+exports.tuple = function () {
     var components = [];
@@ -324,143 +143,37 @@ for (var _i = 0; _i < arguments.length; _i++) {
     }
-    return {
-        decode: function (u) {
-            var e = exports.UnknownArray.decode(u);
-            if (E.isLeft(e)) {
-                return e;
-            }
-            var us = e.right;
-            var a = [];
-            var errors = [];
-            for (var i = 0; i < components.length; i++) {
-                var e_5 = components[i].decode(us[i]);
-                if (E.isLeft(e_5)) {
-                    errors.push(tree("component " + i, e_5.left));
-                }
-                else {
-                    a.push(e_5.right);
-                }
-            }
-            return isNotEmpty(errors) ? E.left(errors) : success(a);
-        }
-    };
-}
-exports.tuple = tuple;
-function typeOf(x) {
-    return x === null ? 'null' : typeof x;
-}
+    return pipeable_1.pipe(exports.UnknownArray, exports.compose(KD.tuple.apply(KD, components)));
+};
 /**
- * @internal
+ * @category combinators
+ * @since 2.2.7
  */
-function intersect(a, b) {
-    if (a !== undefined && b !== undefined) {
-        var tx = typeOf(a);
-        var ty = typeOf(b);
-        if (tx === 'object' || ty === 'object') {
-            return Object.assign({}, a, b);
-        }
-    }
-    return b;
-}
-exports.intersect = intersect;
+exports.union = KD.union;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-function intersection(left, right) {
-    return {
-        decode: function (u) {
-            var ea = left.decode(u);
-            var eb = right.decode(u);
-            if (E.isLeft(ea)) {
-                return E.isLeft(eb) ? E.left(ea.left.concat(eb.left)) : ea;
-            }
-            if (E.isLeft(eb)) {
-                return eb;
-            }
-            return success(intersect(ea.right, eb.right));
-        }
-    };
-}
-exports.intersection = intersection;
+exports.intersect = KD.intersect;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-function lazy(id, f) {
-    var get = Schemable_1.memoize(f);
-    return {
-        decode: function (u) {
-            return pipeable_1.pipe(get().decode(u), E.mapLeft(function (nea) { return [tree(id, nea)]; }));
-        }
-    };
-}
-exports.lazy = lazy;
+exports.sum = function (tag) { return function (members) {
+    return pipeable_1.pipe(exports.object, exports.compose(KD.sum(tag)(members)));
+}; };
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-function sum(tag) {
-    return function (members) {
-        var keys = Object.keys(members);
-        if (keys.length === 0) {
-            return exports.never;
-        }
-        var expected = keys.map(function (k) { return JSON.stringify(k); }).join(' | ');
-        return {
-            decode: function (u) {
-                var e = exports.UnknownRecord.decode(u);
-                if (E.isLeft(e)) {
-                    return e;
-                }
-                var v = e.right[tag];
-                if (v in members) {
-                    return members[v].decode(u);
-                }
-                return E.left([
-                    tree("required property " + JSON.stringify(tag), [
-                        tree("cannot decode " + JSON.stringify(v) + ", should be " + expected)
-                    ])
-                ]);
-            }
-        };
-    };
-}
-exports.sum = sum;
+exports.lazy = KD.lazy;
 /**
  * @category combinators
- * @since 2.2.0
+ * @since 2.2.7
  */
-function union() {
-    var members = [];
-    for (var _i = 0; _i < arguments.length; _i++) {
-        members[_i] = arguments[_i];
-    }
-    var len = members.length;
-    if (len === 0) {
-        return exports.never;
-    }
-    return {
-        decode: function (u) {
-            var e = members[0].decode(u);
-            if (E.isRight(e)) {
-                return e;
-            }
-            else {
-                var errors = [tree("member 0", e.left)];
-                for (var i = 1; i < len; i++) {
-                    var e_6 = members[i].decode(u);
-                    if (E.isRight(e_6)) {
-                        return e_6;
-                    }
-                    else {
-                        errors.push(tree("member " + i, e_6.left));
-                    }
-                }
-                return E.left(errors);
-            }
-        }
-    };
-}
-exports.union = union;
+exports.compose = KD.compose;
 // -------------------------------------------------------------------------------------
+// non-pipeables
+// -------------------------------------------------------------------------------------
+var map_ = function (fa, f) { return pipeable_1.pipe(fa, exports.map(f)); };
+var alt_ = function (me, that) { return pipeable_1.pipe(me, exports.alt(that)); };
+// -------------------------------------------------------------------------------------
 // pipeables
@@ -470,22 +183,10 @@ // -------------------------------------------------------------------------------------
  * @category Functor
- * @since 2.2.0
+ * @since 2.2.7
  */
-exports.map = function (f) { return function (fa) { return map_(fa, f); }; };
-var map_ = function (fa, f) { return ({
-    decode: function (u) {
-        var e = fa.decode(u);
-        return E.isLeft(e) ? e : E.right(f(e.right));
-    }
-}); };
+exports.map = KD.map;
 /**
  * @category Alt
- * @since 2.2.0
+ * @since 2.2.7
  */
-exports.alt = function (that) { return function (fa) { return alt_(fa, that); }; };
-var alt_ = function (fx, fy) { return ({
-    decode: function (u) {
-        var e = fx.decode(u);
-        return E.isLeft(e) ? fy().decode(u) : e;
-    }
-}); };
+exports.alt = KD.alt;
 // -------------------------------------------------------------------------------------
@@ -496,3 +197,3 @@ // instances
  * @category instances
- * @since 2.2.0
+ * @since 2.2.7
  */
@@ -502,3 +203,3 @@ exports.URI = 'io-ts/Decoder';
  * @category instances
- * @since 2.2.3
+ * @since 2.2.7
  */
@@ -511,3 +212,3 @@ exports.functorDecoder = {
  * @category instances
- * @since 2.2.3
+ * @since 2.2.7
  */
@@ -521,23 +222,62 @@ exports.altDecoder = {
  * @category instances
- * @since 2.2.3
+ * @since 2.2.7
  */
 exports.schemableDecoder = {
     URI: exports.URI,
-    literal: literal,
+    literal: exports.literal,
     string: exports.string,
     number: exports.number,
     boolean: exports.boolean,
-    nullable: nullable,
-    type: type,
-    partial: partial,
-    record: record,
-    array: array,
-    tuple: tuple,
-    intersection: intersection,
-    sum: sum,
-    lazy: lazy,
+    nullable: exports.nullable,
+    type: exports.type,
+    partial: exports.partial,
+    record: exports.record,
+    array: exports.array,
+    tuple: exports.tuple,
+    intersect: exports.intersect,
+    sum: exports.sum,
+    lazy: exports.lazy,
     UnknownArray: exports.UnknownArray,
     UnknownRecord: exports.UnknownRecord,
-    union: union,
-    refinement: refinement
+    union: exports.union,
+    refine: exports.refine
 };
+var empty = [];
+var make = function (value, forest) {
+    if (forest === void 0) { forest = empty; }
+    return ({
+        value: value,
+        forest: forest
+    });
+};
+var drawTree = function (tree) { return tree.value + drawForest('\n', tree.forest); };
+var drawForest = function (indentation, forest) {
+    var r = '';
+    var len = forest.length;
+    var tree;
+    for (var i = 0; i < len; i++) {
+        tree = forest[i];
+        var isLast = i === len - 1;
+        r += indentation + (isLast ? '└' : '├') + '─ ' + tree.value;
+        r += drawForest(indentation + (len > 1 && !isLast ? '│  ' : '   '), tree.forest);
+    }
+    return r;
+};
+var toTree = DE.fold({
+    Leaf: function (input, error) { return make("cannot decode " + JSON.stringify(input) + ", should be " + error); },
+    Key: function (key, kind, errors) { return make(kind + " property " + JSON.stringify(key), toForest(errors)); },
+    Index: function (index, kind, errors) { return make(kind + " index " + index, toForest(errors)); },
+    Member: function (index, errors) { return make("member " + index, toForest(errors)); },
+    Lazy: function (id, errors) { return make("lazy type " + id, toForest(errors)); }
+});
+var toForest = FS.fold(function (value) { return [toTree(value)]; }, function (left, right) { return toForest(left).concat(toForest(right)); });
+/**
+ * @since 2.2.7
+ */
+exports.draw = function (e) { return toForest(e).map(drawTree).join('\n'); };
+/**
+ * @internal
+ */
+exports.stringify = 
+/*#__PURE__*/
+E.fold(exports.draw, function (a) { return JSON.stringify(a, null, 2); });

lib/Encoder.d.ts

 /**
+ * **This module is experimental**
+ *
+ * Experimental features are published in order to get early feedback from the community, see these tracking
+ * [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
+ *
+ * A feature tagged as _Experimental_ is in a high state of flux, you're at risk of it changing without notice.
+ *
  * @since 2.2.3
@@ -14,10 +21,2 @@ */
 /**
- * @since 2.2.3
- */
-export declare type TypeOf<E> = E extends Encoder<any, infer A> ? A : never;
-/**
- * @since 2.2.3
- */
-export declare type OutputOf<E> = E extends Encoder<infer O, any> ? O : never;
-/**
  * @category constructors
@@ -73,3 +72,3 @@ * @since 2.2.3
  */
-export declare function intersection<O, A, P, B>(left: Encoder<O, A>, right: Encoder<P, B>): Encoder<O & P, A & B>;
+export declare const intersect: <P, B>(right: Encoder<P, B>) => <O, A>(left: Encoder<O, A>) => Encoder<O & P, A & B>;
 /**
@@ -79,3 +78,3 @@ * @category combinators
  */
-export declare function sum<T extends string>(tag: T): <M extends Record<string, Encoder<any, any>>>(members: M) => Encoder<OutputOf<M[keyof M]>, TypeOf<M[keyof M]>>;
+export declare function sum<T extends string>(tag: T): <MS extends Record<string, Encoder<any, any>>>(members: MS) => Encoder<OutputOf<MS[keyof MS]>, TypeOf<MS[keyof MS]>>;
 /**
@@ -121,1 +120,9 @@ * @category combinators
 export declare const categoryEncoder: Category2<URI>;
+/**
+ * @since 2.2.3
+ */
+export declare type TypeOf<E> = E extends Encoder<any, infer A> ? A : never;
+/**
+ * @since 2.2.3
+ */
+export declare type OutputOf<E> = E extends Encoder<infer O, any> ? O : never;

lib/Encoder.js

 "use strict";
 Object.defineProperty(exports, "__esModule", { value: true });
-exports.categoryEncoder = exports.contravariantEncoder = exports.URI = exports.compose = exports.contramap = exports.lazy = exports.sum = exports.intersection = exports.tuple = exports.array = exports.record = exports.partial = exports.type = exports.nullable = exports.id = void 0;
-var Decoder_1 = require("./Decoder");
+exports.categoryEncoder = exports.contravariantEncoder = exports.URI = exports.compose = exports.contramap = exports.lazy = exports.sum = exports.intersect = exports.tuple = exports.array = exports.record = exports.partial = exports.type = exports.nullable = exports.id = void 0;
 var Schemable_1 = require("./Schemable");
@@ -114,8 +113,5 @@ var function_1 = require("fp-ts/lib/function");
  */
-function intersection(left, right) {
-    return {
-        encode: function (ab) { return Decoder_1.intersect(left.encode(ab), right.encode(ab)); }
-    };
-}
-exports.intersection = intersection;
+exports.intersect = function (right) { return function (left) { return ({
+    encode: function (ab) { return Schemable_1.intersect_(left.encode(ab), right.encode(ab)); }
+}); }; };
 /**
@@ -122,0 +118,0 @@ * @category combinators

lib/Eq.d.ts

 import * as E from 'fp-ts/lib/Eq';
-import { Schemable1, WithRefinement1, WithUnknownContainers1 } from './Schemable';
+import { Schemable1, WithRefine1, WithUnknownContainers1 } from './Schemable';
 import Eq = E.Eq;
@@ -81,3 +81,3 @@ /**
  */
-export declare function intersection<A, B>(left: Eq<A>, right: Eq<B>): Eq<A & B>;
+export declare const intersect: <B>(right: E.Eq<B>) => <A>(left: E.Eq<A>) => E.Eq<A & B>;
 /**
@@ -99,2 +99,2 @@ * @category combinators
  */
-export declare const schemableEq: Schemable1<E.URI> & WithUnknownContainers1<E.URI> & WithRefinement1<E.URI>;
+export declare const schemableEq: Schemable1<E.URI> & WithUnknownContainers1<E.URI> & WithRefine1<E.URI>;

lib/Eq.js

 "use strict";
 Object.defineProperty(exports, "__esModule", { value: true });
-exports.schemableEq = exports.lazy = exports.sum = exports.intersection = exports.tuple = exports.array = exports.record = exports.partial = exports.type = exports.nullable = exports.UnknownRecord = exports.UnknownArray = exports.boolean = exports.number = exports.string = void 0;
+exports.schemableEq = exports.lazy = exports.sum = exports.intersect = exports.tuple = exports.array = exports.record = exports.partial = exports.type = exports.nullable = exports.UnknownRecord = exports.UnknownArray = exports.boolean = exports.number = exports.string = void 0;
 /**
+ * **This module is experimental**
+ *
+ * Experimental features are published in order to get early feedback from the community, see these tracking
+ * [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
+ *
+ * A feature tagged as _Experimental_ is in a high state of flux, you're at risk of it changing without notice.
+ *
  * @since 2.2.2
@@ -107,8 +114,5 @@ */
  */
-function intersection(left, right) {
-    return {
-        equals: function (x, y) { return left.equals(x, y) && right.equals(x, y); }
-    };
-}
-exports.intersection = intersection;
+exports.intersect = function (right) { return function (left) { return ({
+    equals: function (x, y) { return left.equals(x, y) && right.equals(x, y); }
+}); }; };
 /**
@@ -163,3 +167,3 @@ * @category combinators
     tuple: exports.tuple,
-    intersection: intersection,
+    intersect: exports.intersect,
     sum: sum,
@@ -169,3 +173,3 @@ lazy: function (_, f) { return lazy(f); },
     UnknownRecord: exports.UnknownRecord,
-    refinement: function (from) { return from; }
+    refine: function () { return function (from) { return from; }; }
 };

lib/Guard.d.ts

@@ -0,6 +1,3 @@
+import { Literal, Schemable1, WithRefine1, WithUnion1, WithUnknownContainers1 } from './Schemable';
 /**
- * @since 2.2.0
- */
-import { Literal, Schemable1, WithRefinement1, WithUnion1, WithUnknownContainers1 } from './Schemable';
-/**
  * @category model
@@ -20,3 +17,3 @@ * @since 2.2.0
  */
-export declare function literal<A extends ReadonlyArray<Literal>>(...values: A): Guard<A[number]>;
+export declare const literal: <A extends readonly [Literal, ...Literal[]]>(...values: A) => Guard<A[number]>;
 /**
@@ -26,9 +23,6 @@ * @category primitives
  */
-export declare const never: Guard<never>;
-/**
- * @category primitives
- * @since 2.2.0
- */
 export declare const string: Guard<string>;
 /**
+ * Note: `NaN` is excluded.
+ *
  * @category primitives
@@ -57,3 +51,3 @@ * @since 2.2.0
  */
-export declare function refinement<A, B extends A>(from: Guard<A>, refinement: (a: A) => a is B): Guard<B>;
+export declare const refine: <A, B extends A>(refinement: (a: A) => a is B) => (from: Guard<A>) => Guard<B>;
 /**
@@ -63,3 +57,3 @@ * @category combinators
  */
-export declare function nullable<A>(or: Guard<A>): Guard<null | A>;
+export declare const nullable: <A>(or: Guard<A>) => Guard<A | null>;
 /**
@@ -69,7 +63,3 @@ * @category combinators
  */
-export declare function type<A>(properties: {
-    [K in keyof A]: Guard<A[K]>;
-}): Guard<{
-    [K in keyof A]: A[K];
-}>;
+export declare const type: <A>(properties: { [K in keyof A]: Guard<A[K]>; }) => Guard<{ [K_1 in keyof A]: A[K_1]; }>;
 /**
@@ -79,7 +69,3 @@ * @category combinators
  */
-export declare function partial<A>(properties: {
-    [K in keyof A]: Guard<A[K]>;
-}): Guard<Partial<{
-    [K in keyof A]: A[K];
-}>>;
+export declare const partial: <A>(properties: { [K in keyof A]: Guard<A[K]>; }) => Guard<Partial<{ [K_1 in keyof A]: A[K_1]; }>>;
 /**
@@ -89,3 +75,3 @@ * @category combinators
  */
-export declare function record<A>(codomain: Guard<A>): Guard<Record<string, A>>;
+export declare const record: <A>(codomain: Guard<A>) => Guard<Record<string, A>>;
 /**
@@ -95,3 +81,3 @@ * @category combinators
  */
-export declare function array<A>(items: Guard<A>): Guard<Array<A>>;
+export declare const array: <A>(items: Guard<A>) => Guard<A[]>;
 /**
@@ -101,5 +87,3 @@ * @category combinators
  */
-export declare function tuple<A extends ReadonlyArray<unknown>>(...components: {
-    [K in keyof A]: Guard<A[K]>;
-}): Guard<A>;
+export declare const tuple: <A extends readonly unknown[]>(...components: { [K in keyof A]: Guard<A[K]>; }) => Guard<A>;
 /**
@@ -109,3 +93,3 @@ * @category combinators
  */
-export declare function intersection<A, B>(left: Guard<A>, right: Guard<B>): Guard<A & B>;
+export declare const intersect: <B>(right: Guard<B>) => <A>(left: Guard<A>) => Guard<A & B>;
 /**
@@ -115,5 +99,3 @@ * @category combinators
  */
-export declare function union<A extends ReadonlyArray<unknown>>(...members: {
-    [K in keyof A]: Guard<A[K]>;
-}): Guard<A[number]>;
+export declare const union: <A extends readonly [unknown, ...unknown[]]>(...members: { [K in keyof A]: Guard<A[K]>; }) => Guard<A[number]>;
 /**
@@ -123,5 +105,3 @@ * @category combinators
  */
-export declare function sum<T extends string>(tag: T): <A>(members: {
-    [K in keyof A]: Guard<A[K]>;
-}) => Guard<A[keyof A]>;
+export declare const sum: <T extends string>(tag: T) => <A>(members: { [K in keyof A]: Guard<A[K]>; }) => Guard<A[keyof A]>;
 /**
@@ -131,3 +111,3 @@ * @category combinators
  */
-export declare function lazy<A>(f: () => Guard<A>): Guard<A>;
+export declare const lazy: <A>(f: () => Guard<A>) => Guard<A>;
 /**
@@ -152,2 +132,2 @@ * @category instances
  */
-export declare const schemableGuard: Schemable1<URI> & WithUnknownContainers1<URI> & WithUnion1<URI> & WithRefinement1<URI>;
+export declare const schemableGuard: Schemable1<URI> & WithUnknownContainers1<URI> & WithUnion1<URI> & WithRefine1<URI>;

lib/Guard.js

 "use strict";
 Object.defineProperty(exports, "__esModule", { value: true });
-exports.schemableGuard = exports.URI = exports.lazy = exports.sum = exports.union = exports.intersection = exports.tuple = exports.array = exports.record = exports.partial = exports.type = exports.nullable = exports.refinement = exports.UnknownRecord = exports.UnknownArray = exports.boolean = exports.number = exports.string = exports.never = exports.literal = void 0;
+exports.schemableGuard = exports.URI = exports.lazy = exports.sum = exports.union = exports.intersect = exports.tuple = exports.array = exports.record = exports.partial = exports.type = exports.nullable = exports.refine = exports.object = exports.UnknownRecord = exports.UnknownArray = exports.boolean = exports.number = exports.string = exports.literal = void 0;
 /**
+ * **This module is experimental**
+ *
+ * Experimental features are published in order to get early feedback from the community, see these tracking
+ * [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
+ *
+ * A feature tagged as _Experimental_ is in a high state of flux, you're at risk of it changing without notice.
+ *
  * @since 2.2.0
  */
+var pipeable_1 = require("fp-ts/lib/pipeable");
 var Schemable_1 = require("./Schemable");
@@ -15,3 +23,3 @@ // -------------------------------------------------------------------------------------
  */
-function literal() {
+exports.literal = function () {
     var values = [];
@@ -21,7 +29,6 @@ for (var _i = 0; _i < arguments.length; _i++) {
     }
-    return {
+    return ({
         is: function (u) { return values.findIndex(function (a) { return a === u; }) !== -1; }
-    };
-}
-exports.literal = literal;
+    });
+};
 // -------------------------------------------------------------------------------------
@@ -34,9 +41,2 @@ // primitives
  */
-exports.never = {
-    is: function (_u) { return false; }
-};
-/**
- * @category primitives
- * @since 2.2.0
- */
 exports.string = {
@@ -46,2 +46,4 @@ is: function (u) { return typeof u === 'string'; }
 /**
+ * Note: `NaN` is excluded.
+ *
  * @category primitives
@@ -51,3 +53,3 @@ * @since 2.2.0
 exports.number = {
-    is: function (u) { return typeof u === 'number'; }
+    is: function (u) { return typeof u === 'number' && !isNaN(u); }
 };
@@ -75,2 +77,8 @@ /**
 };
+/**
+ * @internal
+ */
+exports.object = {
+    is: function (u) { return u != null && !exports.string.is(u) && !exports.number.is(u) && !exports.boolean.is(u); }
+};
 // -------------------------------------------------------------------------------------
@@ -83,8 +91,5 @@ // combinators
  */
-function refinement(from, refinement) {
-    return {
-        is: function (u) { return from.is(u) && refinement(u); }
-    };
-}
-exports.refinement = refinement;
+exports.refine = function (refinement) { return function (from) { return ({
+    is: function (u) { return from.is(u) && refinement(u); }
+}); }; };
 /**
@@ -94,8 +99,5 @@ * @category combinators
  */
-function nullable(or) {
-    return {
-        is: function (u) { return u === null || or.is(u); }
-    };
-}
-exports.nullable = nullable;
+exports.nullable = function (or) { return ({
+    is: function (u) { return u === null || or.is(u); }
+}); };
 /**
@@ -105,4 +107,4 @@ * @category combinators
  */
-function type(properties) {
-    return refinement(exports.UnknownRecord, function (r) {
+exports.type = function (properties) {
+    return pipeable_1.pipe(exports.UnknownRecord, exports.refine(function (r) {
         for (var k in properties) {
@@ -114,5 +116,4 @@ if (!(k in r) || !properties[k].is(r[k])) {
         return true;
-    });
-}
-exports.type = type;
+    }));
+};
 /**
@@ -122,4 +123,4 @@ * @category combinators
  */
-function partial(properties) {
-    return refinement(exports.UnknownRecord, function (r) {
+exports.partial = function (properties) {
+    return pipeable_1.pipe(exports.UnknownRecord, exports.refine(function (r) {
         for (var k in properties) {
@@ -132,5 +133,4 @@ var v = r[k];
         return true;
-    });
-}
-exports.partial = partial;
+    }));
+};
 /**
@@ -140,4 +140,4 @@ * @category combinators
  */
-function record(codomain) {
-    return refinement(exports.UnknownRecord, function (r) {
+exports.record = function (codomain) {
+    return pipeable_1.pipe(exports.UnknownRecord, exports.refine(function (r) {
         for (var k in r) {
@@ -149,5 +149,4 @@ if (!codomain.is(r[k])) {
         return true;
-    });
-}
-exports.record = record;
+    }));
+};
 /**
@@ -157,6 +156,5 @@ * @category combinators
  */
-function array(items) {
-    return refinement(exports.UnknownArray, function (us) { return us.every(items.is); });
-}
-exports.array = array;
+exports.array = function (items) {
+    return pipeable_1.pipe(exports.UnknownArray, exports.refine(function (us) { return us.every(items.is); }));
+};
 /**
@@ -166,3 +164,3 @@ * @category combinators
  */
-function tuple() {
+exports.tuple = function () {
     var components = [];
@@ -172,7 +170,6 @@ for (var _i = 0; _i < arguments.length; _i++) {
     }
-    return {
+    return ({
         is: function (u) { return Array.isArray(u) && u.length === components.length && components.every(function (c, i) { return c.is(u[i]); }); }
-    };
-}
-exports.tuple = tuple;
+    });
+};
 /**
@@ -182,8 +179,5 @@ * @category combinators
  */
-function intersection(left, right) {
-    return {
-        is: function (u) { return left.is(u) && right.is(u); }
-    };
-}
-exports.intersection = intersection;
+exports.intersect = function (right) { return function (left) { return ({
+    is: function (u) { return left.is(u) && right.is(u); }
+}); }; };
 /**
@@ -193,3 +187,3 @@ * @category combinators
  */
-function union() {
+exports.union = function () {
     var members = [];
@@ -199,7 +193,6 @@ for (var _i = 0; _i < arguments.length; _i++) {
     }
-    return {
+    return ({
         is: function (u) { return members.some(function (m) { return m.is(u); }); }
-    };
-}
-exports.union = union;
+    });
+};
 /**
@@ -209,14 +202,11 @@ * @category combinators
  */
-function sum(tag) {
-    return function (members) {
-        return refinement(exports.UnknownRecord, function (r) {
-            var v = r[tag];
-            if (v in members) {
-                return members[v].is(r);
-            }
-            return false;
-        });
-    };
-}
-exports.sum = sum;
+exports.sum = function (tag) { return function (members) {
+    return pipeable_1.pipe(exports.UnknownRecord, exports.refine(function (r) {
+        var v = r[tag];
+        if (v in members) {
+            return members[v].is(r);
+        }
+        return false;
+    }));
+}; };
 /**
@@ -226,3 +216,3 @@ * @category combinators
  */
-function lazy(f) {
+exports.lazy = function (f) {
     var get = Schemable_1.memoize(f);
@@ -232,4 +222,3 @@ return {
     };
-}
-exports.lazy = lazy;
+};
 // -------------------------------------------------------------------------------------
@@ -249,19 +238,19 @@ // instances
     URI: exports.URI,
-    literal: literal,
+    literal: exports.literal,
     string: exports.string,
     number: exports.number,
     boolean: exports.boolean,
-    nullable: nullable,
-    type: type,
-    partial: partial,
-    record: record,
-    array: array,
-    tuple: tuple,
-    intersection: intersection,
-    sum: sum,
-    lazy: function (_, f) { return lazy(f); },
+    nullable: exports.nullable,
+    type: exports.type,
+    partial: exports.partial,
+    record: exports.record,
+    array: exports.array,
+    tuple: exports.tuple,
+    intersect: exports.intersect,
+    sum: exports.sum,
+    lazy: function (_, f) { return exports.lazy(f); },
     UnknownArray: exports.UnknownArray,
     UnknownRecord: exports.UnknownRecord,
-    union: union,
-    refinement: refinement
+    union: exports.union,
+    refine: exports.refine
 };

lib/JsonCodec.d.ts

 /**
+ * **This module is experimental**
+ *
+ * Experimental features are published in order to get early feedback from the community, see these tracking
+ * [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
+ *
+ * A feature tagged as _Experimental_ is in a high state of flux, you're at risk of it changing without notice.
+ *
  * @since 2.2.3
@@ -8,3 +15,3 @@ */
 import * as C from './Codec';
-import { Literal, Schemable1, WithRefinement1 } from './Schemable';
+import { Literal, Schemable1, WithRefine1 } from './Schemable';
 /**
@@ -34,3 +41,3 @@ * Laws:
  */
-export declare const literal: <A extends ReadonlyArray<Literal>>(...values: A) => JsonCodec<A[number]>;
+export declare const literal: <A extends readonly [Literal, ...Array<Literal>]>(...values: A) => JsonCodec<A[number]>;
 /**
@@ -55,3 +62,3 @@ * @category primitives
  */
-export declare const withExpected: <A>(codec: JsonCodec<A>, expected: (actual: unknown, e: D.DecodeError) => D.DecodeError) => JsonCodec<A>;
+export declare const mapLeftWithInput: (f: (actual: unknown, e: D.DecodeError) => D.DecodeError) => <A>(codec: JsonCodec<A>) => JsonCodec<A>;
 /**
@@ -61,3 +68,3 @@ * @category combinators
  */
-export declare const refinement: <A, B extends A>(from: JsonCodec<A>, refinement: (a: A) => a is B, expected: string) => JsonCodec<B>;
+export declare const refine: <A, B extends A>(refinement: (a: A) => a is B, id: string) => (from: JsonCodec<A>) => JsonCodec<B>;
 /**
@@ -107,3 +114,3 @@ * @category combinators
  */
-export declare const intersection: <A, B>(left: JsonCodec<A>, right: JsonCodec<B>) => JsonCodec<A & B>;
+export declare const intersect: <B>(right: JsonCodec<B>) => <A>(left: JsonCodec<A>) => JsonCodec<A & B>;
 /**
@@ -150,2 +157,2 @@ * @category combinators
  */
-export declare const schemableJsonCodec: Schemable1<URI> & WithRefinement1<URI>;
+export declare const schemableJsonCodec: Schemable1<URI> & WithRefine1<URI>;

lib/JsonCodec.js

 "use strict";
 Object.defineProperty(exports, "__esModule", { value: true });
-exports.schemableJsonCodec = exports.invariantJsonCodec = exports.URI = exports.imap = exports.lazy = exports.sum = exports.intersection = exports.tuple = exports.array = exports.record = exports.partial = exports.type = exports.nullable = exports.refinement = exports.withExpected = exports.boolean = exports.number = exports.string = exports.literal = exports.make = void 0;
+exports.schemableJsonCodec = exports.invariantJsonCodec = exports.URI = exports.imap = exports.lazy = exports.sum = exports.intersect = exports.tuple = exports.array = exports.record = exports.partial = exports.type = exports.nullable = exports.refine = exports.mapLeftWithInput = exports.boolean = exports.number = exports.string = exports.literal = exports.make = void 0;
 var C = require("./Codec");
@@ -43,3 +43,3 @@ // -------------------------------------------------------------------------------------
  */
-exports.withExpected = C.withExpected;
+exports.mapLeftWithInput = C.mapLeftWithInput;
 /**
@@ -49,3 +49,3 @@ * @category combinators
  */
-exports.refinement = C.refinement;
+exports.refine = C.refine;
 /**
@@ -85,3 +85,3 @@ * @category combinators
  */
-exports.intersection = C.intersection;
+exports.intersect = C.intersect;
 /**
@@ -137,6 +137,6 @@ * @category combinators
     tuple: exports.tuple,
-    intersection: exports.intersection,
+    intersect: exports.intersect,
     sum: exports.sum,
     lazy: exports.lazy,
-    refinement: exports.refinement
+    refine: exports.refine
 };

lib/JsonEncoder.d.ts

 /**
+ * **This module is experimental**
+ *
+ * Experimental features are published in order to get early feedback from the community, see these tracking
+ * [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
+ *
+ * A feature tagged as _Experimental_ is in a high state of flux, you're at risk of it changing without notice.
+ *
  * @since 2.2.3
@@ -11,3 +18,3 @@ */
  */
-export interface JsonArray extends Array<Json> {
+export interface JsonArray extends ReadonlyArray<Json> {
 }
@@ -18,5 +25,5 @@ /**
  */
-export declare type JsonObject = {
-    [key: string]: Json;
-};
+export interface JsonRecord {
+    readonly [key: string]: Json;
+}
 /**
@@ -26,3 +33,3 @@ * @category model
  */
-export declare type Json = null | string | number | boolean | JsonObject | JsonArray;
+export declare type Json = null | string | number | boolean | JsonRecord | JsonArray;
 /**
@@ -88,3 +95,3 @@ * @category model
  */
-export declare const intersection: <A, B>(left: JsonEncoder<A>, right: JsonEncoder<B>) => JsonEncoder<A & B>;
+export declare const intersect: <B>(right: JsonEncoder<B>) => <A>(left: JsonEncoder<A>) => JsonEncoder<A & B>;
 /**
@@ -91,0 +98,0 @@ * @category combinators

lib/JsonEncoder.js

 "use strict";
 Object.defineProperty(exports, "__esModule", { value: true });
-exports.schemableJsonEncoder = exports.contravariantJsonEncoder = exports.URI = exports.contramap = exports.lazy = exports.sum = exports.intersection = exports.tuple = exports.array = exports.record = exports.partial = exports.type = exports.nullable = exports.id = void 0;
+exports.schemableJsonEncoder = exports.contravariantJsonEncoder = exports.URI = exports.contramap = exports.lazy = exports.sum = exports.intersect = exports.tuple = exports.array = exports.record = exports.partial = exports.type = exports.nullable = exports.id = void 0;
 var function_1 = require("fp-ts/lib/function");
@@ -56,3 +56,3 @@ var E = require("./Encoder");
  */
-exports.intersection = E.intersection;
+exports.intersect = E.intersect;
 /**
@@ -108,5 +108,5 @@ * @category combinators
     tuple: exports.tuple,
-    intersection: exports.intersection,
+    intersect: exports.intersect,
     sum: exports.sum,
     lazy: function (_, f) { return exports.lazy(f); }
 };

lib/Schema.d.ts

 /**
+ * **This module is experimental**
+ *
+ * Experimental features are published in order to get early feedback from the community, see these tracking
+ * [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
+ *
+ * A feature tagged as _Experimental_ is in a high state of flux, you're at risk of it changing without notice.
+ *
  * @since 2.2.0
@@ -3,0 +10,0 @@ */

lib/Schemable.d.ts

 /**
+ * **This module is experimental**
+ *
+ * Experimental features are published in order to get early feedback from the community, see these tracking
+ * [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
+ *
+ * A feature tagged as _Experimental_ is in a high state of flux, you're at risk of it changing without notice.
+ *
  * @since 2.2.0
@@ -14,3 +21,3 @@ */
     readonly URI: S;
-    readonly literal: <A extends ReadonlyArray<Literal>>(...values: A) => HKT<S, A[number]>;
+    readonly literal: <A extends readonly [Literal, ...Array<Literal>]>(...values: A) => HKT<S, A[number]>;
     readonly string: HKT<S, string>;
@@ -35,3 +42,3 @@ readonly number: HKT<S, number>;
     }) => HKT<S, A>;
-    readonly intersection: <A, B>(left: HKT<S, A>, right: HKT<S, B>) => HKT<S, A & B>;
+    readonly intersect: <B>(right: HKT<S, B>) => <A>(left: HKT<S, A>) => HKT<S, A & B>;
     readonly sum: <T extends string>(tag: T) => <A>(members: {
@@ -47,3 +54,3 @@ [K in keyof A]: HKT<S, A[K]>;
     readonly URI: S;
-    readonly literal: <A extends ReadonlyArray<Literal>>(...values: A) => Kind<S, A[number]>;
+    readonly literal: <A extends readonly [Literal, ...Array<Literal>]>(...values: A) => Kind<S, A[number]>;
     readonly string: Kind<S, string>;
@@ -68,3 +75,3 @@ readonly number: Kind<S, number>;
     }) => Kind<S, A>;
-    readonly intersection: <A, B>(left: Kind<S, A>, right: Kind<S, B>) => Kind<S, A & B>;
+    readonly intersect: <B>(right: Kind<S, B>) => <A>(left: Kind<S, A>) => Kind<S, A & B>;
     readonly sum: <T extends string>(tag: T) => <A>(members: {
@@ -93,3 +100,3 @@ [K in keyof A]: Kind<S, A[K]>;
 export interface WithUnion<S> {
-    readonly union: <A extends ReadonlyArray<unknown>>(...members: {
+    readonly union: <A extends readonly [unknown, ...Array<unknown>]>(...members: {
         [K in keyof A]: HKT<S, A[K]>;
@@ -102,3 +109,3 @@ }) => HKT<S, A[number]>;
 export interface WithUnion1<S extends URIS> {
-    readonly union: <A extends ReadonlyArray<unknown>>(...members: {
+    readonly union: <A extends readonly [unknown, ...Array<unknown>]>(...members: {
         [K in keyof A]: Kind<S, A[K]>;
@@ -110,4 +117,4 @@ }) => Kind<S, A[number]>;
  */
-export interface WithRefinement<S> {
-    readonly refinement: <A, B extends A>(from: HKT<S, A>, refinement: (a: A) => a is B, expected: string) => HKT<S, B>;
+export interface WithRefine<S> {
+    readonly refine: <A, B extends A>(refinement: (a: A) => a is B, id: string) => (from: HKT<S, A>) => HKT<S, B>;
 }
@@ -117,4 +124,4 @@ /**
  */
-export interface WithRefinement1<S extends URIS> {
-    readonly refinement: <A, B extends A>(from: Kind<S, A>, refinement: (a: A) => a is B, expected: string) => Kind<S, B>;
+export interface WithRefine1<S extends URIS> {
+    readonly refine: <A, B extends A>(refinement: (a: A) => a is B, id: string) => (from: Kind<S, A>) => Kind<S, B>;
 }
@@ -121,0 +128,0 @@ /**

lib/Schemable.js

 "use strict";
 Object.defineProperty(exports, "__esModule", { value: true });
-exports.memoize = void 0;
+exports.intersect_ = exports.memoize = void 0;
 /**
@@ -19,1 +19,18 @@ * @since 2.2.0
 exports.memoize = memoize;
+// -------------------------------------------------------------------------------------
+// utils
+// -------------------------------------------------------------------------------------
+var typeOf = function (x) { return (x === null ? 'null' : typeof x); };
+/**
+ * @internal
+ */
+exports.intersect_ = function (a, b) {
+    if (a !== undefined && b !== undefined) {
+        var tx = typeOf(a);
+        var ty = typeOf(b);
+        if (tx === 'object' || ty === 'object') {
+            return Object.assign({}, a, b);
+        }
+    }
+    return b;
+};

lib/Type.d.ts

 /**
+ * **This module is experimental**
+ *
+ * Experimental features are published in order to get early feedback from the community, see these tracking
+ * [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
+ *
+ * A feature tagged as _Experimental_ is in a high state of flux, you're at risk of it changing without notice.
+ *
  * @since 2.2.3
  */
 import * as t from './index';
-import { Literal, Schemable1, WithUnion1, WithRefinement1, WithUnknownContainers1 } from './Schemable';
+import { Literal, Schemable1, WithUnion1, WithRefine1, WithUnknownContainers1 } from './Schemable';
 /**
@@ -16,3 +23,3 @@ * @category model
  */
-export declare function literal<A extends ReadonlyArray<Literal>>(...values: A): Type<A[number]>;
+export declare const literal: <A extends readonly [Literal, ...Literal[]]>(...values: A) => Type<A[number]>;
 /**
@@ -47,3 +54,3 @@ * @category primitives
  */
-export declare function refinement<A, B extends A>(from: Type<A>, refinement: (a: A) => a is B, expected: string): Type<B>;
+export declare const refine: <A, B extends A>(refinement: (a: A) => a is B, id: string) => (from: Type<A>) => Type<B>;
 /**
@@ -53,3 +60,3 @@ * @category combinators
  */
-export declare function nullable<A>(or: Type<A>): Type<null | A>;
+export declare const nullable: <A>(or: Type<A>) => Type<A | null>;
 /**
@@ -59,7 +66,3 @@ * @category combinators
  */
-export declare function type<A>(properties: {
-    [K in keyof A]: Type<A[K]>;
-}): Type<{
-    [K in keyof A]: A[K];
-}>;
+export declare const type: <A>(properties: { [K in keyof A]: Type<A[K]>; }) => Type<{ [K_1 in keyof A]: A[K_1]; }>;
 /**
@@ -69,7 +72,3 @@ * @category combinators
  */
-export declare function partial<A>(properties: {
-    [K in keyof A]: Type<A[K]>;
-}): Type<Partial<{
-    [K in keyof A]: A[K];
-}>>;
+export declare const partial: <A>(properties: { [K in keyof A]: Type<A[K]>; }) => Type<Partial<{ [K_1 in keyof A]: A[K_1]; }>>;
 /**
@@ -79,3 +78,3 @@ * @category combinators
  */
-export declare function record<A>(codomain: Type<A>): Type<Record<string, A>>;
+export declare const record: <A>(codomain: Type<A>) => Type<Record<string, A>>;
 /**
@@ -85,3 +84,3 @@ * @category combinators
  */
-export declare function array<A>(items: Type<A>): Type<Array<A>>;
+export declare const array: <A>(items: Type<A>) => Type<A[]>;
 /**
@@ -91,5 +90,3 @@ * @category combinators
  */
-export declare function tuple<A extends ReadonlyArray<unknown>>(...components: {
-    [K in keyof A]: Type<A[K]>;
-}): Type<A>;
+export declare const tuple: <A extends readonly unknown[]>(...components: { [K in keyof A]: Type<A[K]>; }) => Type<A>;
 /**
@@ -99,3 +96,3 @@ * @category combinators
  */
-export declare function intersection<A, B>(left: Type<A>, right: Type<B>): Type<A & B>;
+export declare const intersect: <B>(right: Type<B>) => <A>(left: Type<A>) => Type<A & B>;
 /**
@@ -105,3 +102,3 @@ * @category combinators
  */
-export declare function lazy<A>(id: string, f: () => Type<A>): Type<A>;
+export declare const lazy: <A>(id: string, f: () => Type<A>) => Type<A>;
 /**
@@ -111,5 +108,3 @@ * @category combinators
  */
-export declare function sum<T extends string>(_tag: T): <A>(members: {
-    [K in keyof A]: Type<A[K]>;
-}) => Type<A[keyof A]>;
+export declare const sum: <T extends string>(_tag: T) => <A>(members: { [K in keyof A]: Type<A[K]>; }) => Type<A[keyof A]>;
 /**
@@ -119,5 +114,3 @@ * @category combinators
  */
-export declare function union<A extends ReadonlyArray<unknown>>(...members: {
-    [K in keyof A]: Type<A[K]>;
-}): Type<A[number]>;
+export declare const union: <A extends readonly [unknown, ...unknown[]]>(...members: { [K in keyof A]: Type<A[K]>; }) => Type<A[number]>;
 /**
@@ -142,2 +135,2 @@ * @category instances
  */
-export declare const schemableType: Schemable1<URI> & WithUnknownContainers1<URI> & WithUnion1<URI> & WithRefinement1<URI>;
+export declare const schemableType: Schemable1<URI> & WithUnknownContainers1<URI> & WithUnion1<URI> & WithRefine1<URI>;

lib/Type.js

 "use strict";
 Object.defineProperty(exports, "__esModule", { value: true });
-exports.schemableType = exports.URI = exports.union = exports.sum = exports.lazy = exports.intersection = exports.tuple = exports.array = exports.record = exports.partial = exports.type = exports.nullable = exports.refinement = exports.UnknownRecord = exports.UnknownArray = exports.boolean = exports.number = exports.string = exports.literal = void 0;
+exports.schemableType = exports.URI = exports.union = exports.sum = exports.lazy = exports.intersect = exports.tuple = exports.array = exports.record = exports.partial = exports.type = exports.nullable = exports.refine = exports.UnknownRecord = exports.UnknownArray = exports.boolean = exports.number = exports.string = exports.literal = void 0;
 /**
+ * **This module is experimental**
+ *
+ * Experimental features are published in order to get early feedback from the community, see these tracking
+ * [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
+ *
+ * A feature tagged as _Experimental_ is in a high state of flux, you're at risk of it changing without notice.
+ *
  * @since 2.2.3
  */
 var t = require("./index");
+var E = require("fp-ts/lib/Either");
+var pipeable_1 = require("fp-ts/lib/pipeable");
 // -------------------------------------------------------------------------------------
@@ -15,3 +24,3 @@ // constructors
  */
-function literal() {
+exports.literal = function () {
     var values = [];
@@ -22,4 +31,3 @@ for (var _i = 0; _i < arguments.length; _i++) {
     return t.union(values.map(function (v) { return t.literal(v); }));
-}
-exports.literal = literal;
+};
 // -------------------------------------------------------------------------------------
@@ -37,3 +45,5 @@ // primitives
  */
-exports.number = t.number;
+exports.number = new t.Type(t.number.name, t.number.is, function (u, c) {
+    return pipeable_1.pipe(t.number.decode(u), E.chain(function (n) { return (isNaN(n) ? t.failure(u, c) : t.success(n)); }));
+}, t.number.encode);
 /**
@@ -61,7 +71,6 @@ * @category primitives
  */
-function refinement(from, refinement, expected) {
+exports.refine = function (refinement, id) { return function (from) {
     // tslint:disable-next-line: deprecation
-    return t.refinement(from, refinement, expected);
-}
-exports.refinement = refinement;
+    return t.refinement(from, refinement, id);
+}; };
 /**
@@ -71,6 +80,3 @@ * @category combinators
  */
-function nullable(or) {
-    return t.union([t.null, or]);
-}
-exports.nullable = nullable;
+exports.nullable = function (or) { return t.union([t.null, or]); };
 /**
@@ -80,6 +86,5 @@ * @category combinators
  */
-function type(properties) {
+exports.type = function (properties) {
     return t.type(properties);
-}
-exports.type = type;
+};
 /**
@@ -89,6 +94,5 @@ * @category combinators
  */
-function partial(properties) {
+exports.partial = function (properties) {
     return t.partial(properties);
-}
-exports.partial = partial;
+};
 /**
@@ -98,6 +102,3 @@ * @category combinators
  */
-function record(codomain) {
-    return t.record(t.string, codomain);
-}
-exports.record = record;
+exports.record = function (codomain) { return t.record(t.string, codomain); };
 /**
@@ -107,6 +108,3 @@ * @category combinators
  */
-function array(items) {
-    return t.array(items);
-}
-exports.array = array;
+exports.array = function (items) { return t.array(items); };
 /**
@@ -116,3 +114,3 @@ * @category combinators
  */
-function tuple() {
+exports.tuple = function () {
     var components = [];
@@ -123,4 +121,3 @@ for (var _i = 0; _i < arguments.length; _i++) {
     return t.tuple(components);
-}
-exports.tuple = tuple;
+};
 /**
@@ -130,6 +127,3 @@ * @category combinators
  */
-function intersection(left, right) {
-    return t.intersection([left, right]);
-}
-exports.intersection = intersection;
+exports.intersect = function (right) { return function (left) { return t.intersection([left, right]); }; };
 /**
@@ -139,6 +133,3 @@ * @category combinators
  */
-function lazy(id, f) {
-    return t.recursion(id, f);
-}
-exports.lazy = lazy;
+exports.lazy = function (id, f) { return t.recursion(id, f); };
 /**
@@ -148,6 +139,5 @@ * @category combinators
  */
-function sum(_tag) {
-    return function (members) { return t.union(Object.values(members)); };
-}
-exports.sum = sum;
+exports.sum = function (_tag) { return function (members) {
+    return t.union(Object.values(members));
+}; };
 /**
@@ -157,3 +147,3 @@ * @category combinators
  */
-function union() {
+exports.union = function () {
     var members = [];
@@ -164,4 +154,3 @@ for (var _i = 0; _i < arguments.length; _i++) {
     return t.union(members);
-}
-exports.union = union;
+};
 // -------------------------------------------------------------------------------------
@@ -181,19 +170,19 @@ // instances
     URI: exports.URI,
-    literal: literal,
+    literal: exports.literal,
     string: exports.string,
     number: exports.number,
     boolean: exports.boolean,
-    nullable: nullable,
-    type: type,
-    partial: partial,
-    record: record,
-    array: array,
-    tuple: tuple,
-    intersection: intersection,
-    sum: sum,
-    lazy: lazy,
+    nullable: exports.nullable,
+    type: exports.type,
+    partial: exports.partial,
+    record: exports.record,
+    array: exports.array,
+    tuple: exports.tuple,
+    intersect: exports.intersect,
+    sum: exports.sum,
+    lazy: exports.lazy,
     UnknownArray: exports.UnknownArray,
     UnknownRecord: exports.UnknownRecord,
-    union: union,
-    refinement: refinement
+    union: exports.union,
+    refine: exports.refine
 };

package.json

 {
   "name": "io-ts",
-  "version": "2.2.6",
+  "version": "2.2.7",
   "description": "TypeScript runtime type system for IO decoding/encoding",
@@ -25,3 +25,3 @@ "files": [
     "mocha": "TS_NODE_CACHE=false mocha -r ts-node/register test/*.ts",
-    "doctoc": "doctoc README.md Type.md Decoder.md Encoder.md Codec.md Eq.md Schema.md",
+    "doctoc": "doctoc README.md index.md Decoder.md Encoder.md Codec.md Eq.md Schema.md",
     "docs": "docs-ts",
@@ -28,0 +28,0 @@ "import-path-rewrite": "import-path-rewrite"

README.md

@@ -33,3 +33,3 @@ [![build status](https://img.shields.io/travis/gcanti/io-ts/master.svg?style=flat-square)](https://travis-ci.org/gcanti/io-ts)
 
-Experimental features are published in order to get early feedback from the community, see these tracking [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
+Experimental features (\*) are published in order to get early feedback from the community, see these tracking [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
 
@@ -41,1 +41,3 @@ - [`Decoder.ts` module](Decoder.md)
 - [`Schema.ts` module (advanced feature)](Schema.md)
+
+(\*) A feature tagged as _Experimental_ is in a high state of flux, you're at risk of it changing without notice.

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Improved metrics

Total package byte prevSize

448567

increased by31.76%

Number of package files

84

increased by31.25%

Lines of code

15155

increased by26.17%

Number of lines in readme file

42

increased by5%

No dependency changes