ts-pattern - npm Package Compare versions

Comparing version 5.0.3-rc.1 to 5.0.3-rc.2

dist/patterns.d.ts

@@ -50,6 +50,19 @@ import * as symbols from './internals/symbols.js';
  */
-export type infer<p extends Pattern<any>> = InvertPattern<p, unknown>;
-export type narrow<i, p extends Pattern<any>> = ExtractPreciseValue<i, InvertPattern<p, i>>;
-type Variadic<p> = p & Iterable<p>;
-type ArrayChainable<p, omitted extends string = never> = Variadic<p> & Omit<{
+export type infer<pattern extends Pattern<any>> = InvertPattern<pattern, unknown>;
+/**
+ * `P.narrow<Input, Pattern>` will narrow the input type to only keep
+ * the set of values that are compatible with the provided pattern type.
+ *
+ * [Read the documentation for `P.narrow` on GitHub](https://github.com/gvergnaud/ts-pattern#Pnarrow)
+ *
+ * @example
+ * type Input = ['a' | 'b' | 'c', 'a' | 'b' | 'c']
+ * const Pattern = ['a', P.union('a', 'b')] as const
+ *
+ * type Narrowed = P.narrow<Input, typeof Pattern>
+ * //     ^? ['a', 'a' | 'b']
+ */
+export type narrow<input, pattern extends Pattern<any>> = ExtractPreciseValue<input, InvertPattern<pattern, input>>;
+type Variadic<pattern> = pattern & Iterable<pattern>;
+type ArrayChainable<pattern, omitted extends string = never> = Variadic<pattern> & Omit<{
     /**
@@ -65,3 +78,3 @@ * `.optional()` returns a pattern which matches if the
      */
-    optional<input>(): ArrayChainable<OptionalP<input, p>, omitted | 'optional'>;
+    optional<input>(): ArrayChainable<OptionalP<input, pattern>, omitted | 'optional'>;
     /**
@@ -76,4 +89,4 @@ * `P.select()` will inject this property into the handler function's arguments.
      */
-    select<input>(): ArrayChainable<SelectP<symbols.anonymousSelectKey, input, p>, omitted | 'select'>;
-    select<input, k extends string>(key: k): ArrayChainable<SelectP<k, input, p>, omitted | 'select'>;
+    select<input>(): ArrayChainable<SelectP<symbols.anonymousSelectKey, input, pattern>, omitted | 'select'>;
+    select<input, k extends string>(key: k): ArrayChainable<SelectP<k, input, pattern>, omitted | 'select'>;
 }, omitted>;
@@ -90,3 +103,3 @@ /**
  */
-export declare function optional<input, const p extends unknown extends input ? UnknownPattern : Pattern<input>>(pattern: p): Chainable<OptionalP<input, p>, 'optional'>;
+export declare function optional<input, const pattern extends unknown extends input ? UnknownPattern : Pattern<input>>(pattern: pattern): Chainable<OptionalP<input, pattern>, 'optional'>;
 type UnwrapArray<xs> = xs extends readonly (infer x)[] ? x : never;
@@ -108,3 +121,3 @@ type UnwrapSet<xs> = xs extends Set<infer x> ? x : never;
 export declare function array<input>(): ArrayChainable<ArrayP<input, unknown>>;
-export declare function array<input, const p extends Pattern<WithDefault<UnwrapArray<input>, unknown>>>(pattern: p): ArrayChainable<ArrayP<input, p>>;
+export declare function array<input, const pattern extends Pattern<WithDefault<UnwrapArray<input>, unknown>>>(pattern: pattern): ArrayChainable<ArrayP<input, pattern>>;
 /**
@@ -121,3 +134,3 @@ * `P.set(subpattern)` takes a sub pattern and returns a pattern that matches
 export declare function set<input>(): Chainable<SetP<input, unknown>>;
-export declare function set<input, const p extends Pattern<WithDefault<UnwrapSet<input>, unknown>>>(pattern: p): Chainable<SetP<input, p>>;
+export declare function set<input, const pattern extends Pattern<WithDefault<UnwrapSet<input>, unknown>>>(pattern: pattern): Chainable<SetP<input, pattern>>;
 /**
@@ -154,3 +167,3 @@ * `P.set(subpattern)` takes a sub pattern and returns a pattern that matches
  */
-export declare function intersection<input, const ps extends readonly [Pattern<input>, ...Pattern<input>[]]>(...patterns: ps): Chainable<AndP<input, ps>>;
+export declare function intersection<input, const patterns extends readonly [Pattern<input>, ...Pattern<input>[]]>(...patterns: patterns): Chainable<AndP<input, patterns>>;
 /**
@@ -169,3 +182,3 @@ * `P.union(...patterns)` returns a pattern which matches
  */
-export declare function union<input, const ps extends readonly [Pattern<input>, ...Pattern<input>[]]>(...patterns: ps): Chainable<OrP<input, ps>>;
+export declare function union<input, const patterns extends readonly [Pattern<input>, ...Pattern<input>[]]>(...patterns: patterns): Chainable<OrP<input, patterns>>;
 /**
@@ -182,3 +195,3 @@ * `P.not(pattern)` returns a pattern which matches if the sub pattern
  */
-export declare function not<input, const p extends Pattern<input> | UnknownPattern>(pattern: p): Chainable<NotP<input, p>>;
+export declare function not<input, const pattern extends Pattern<input> | UnknownPattern>(pattern: pattern): Chainable<NotP<input, pattern>>;
 /**
@@ -195,3 +208,3 @@ * `P.when((value) => boolean)` returns a pattern which matches
  */
-export declare function when<input, p extends (value: input) => unknown>(predicate: p): GuardP<input, p extends (value: any) => value is infer narrowed ? narrowed : never>;
+export declare function when<input, predicate extends (value: input) => unknown>(predicate: predicate): GuardP<input, predicate extends (value: any) => value is infer narrowed ? narrowed : never>;
 export declare function when<input, narrowed extends input, excluded>(predicate: (input: input) => input is narrowed): GuardExcludeP<input, narrowed, excluded>;
@@ -211,3 +224,3 @@ /**
 export declare function select<input, const patternOrKey extends string | (unknown extends input ? UnknownPattern : Pattern<input>)>(patternOrKey: patternOrKey): patternOrKey extends string ? Chainable<SelectP<patternOrKey, 'select' | 'or' | 'and'>> : Chainable<SelectP<symbols.anonymousSelectKey, input, patternOrKey>, 'select' | 'or' | 'and'>;
-export declare function select<input, const p extends unknown extends input ? UnknownPattern : Pattern<input>, const k extends string>(key: k, pattern: p): Chainable<SelectP<k, input, p>, 'select' | 'or' | 'and'>;
+export declare function select<input, const pattern extends unknown extends input ? UnknownPattern : Pattern<input>, const k extends string>(key: k, pattern: pattern): Chainable<SelectP<k, input, pattern>, 'select' | 'or' | 'and'>;
 type AnyConstructor = abstract new (...args: any[]) => any;
@@ -476,2 +489,2 @@ /**
  */
-export declare function shape<input, const p extends Pattern<input>>(pattern: p): Chainable<GuardP<input, InvertPattern<p, input>>>;
+export declare function shape<input, const pattern extends Pattern<input>>(pattern: pattern): Chainable<GuardP<input, InvertPattern<pattern, input>>>;

package.json

 {
   "name": "ts-pattern",
-  "version": "5.0.3-rc.1",
+  "version": "5.0.3-rc.2",
   "description": " The exhaustive Pattern Matching library for TypeScript.",
@@ -5,0 +5,0 @@ "type": "module",

README.md

@@ -1534,2 +1534,16 @@ <h1 align="center">TS-Pattern</h1>
 
+### `P.narrow`
+
+`P.narrow<Input, typeof Pattern>` will narrow the input type to only keep the set of values that are compatible with the provided pattern type.
+
+```ts
+type Input = ['a' | 'b' | 'c', 'a' | 'b' | 'c'];
+const Pattern = ['a', P.union('a', 'b')] as const;
+
+type Narrowed = P.narrow<Input, typeof Pattern>;
+//     ^? ['a', 'a' | 'b']
+```
+
+Note that most of the time, the `match` and `isMatching` functions perform narrowing for you, and you do not need to narrow types yourself.
+
 ### `P.Pattern`
@@ -1536,0 +1550,0 @@

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422597

increased by1.12%

Lines of code

1603

increased by0.82%

Number of lines in readme file

1656

increased by0.85%

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