@helios-lang/type-utils - npm Package Compare versions

Comparing version 0.1.6 to 0.1.7

package.json

 {
     "name": "@helios-lang/type-utils",
-    "version": "0.1.6",
+    "version": "0.1.7",
     "description": "Global utility types",
@@ -5,0 +5,0 @@ "main": "src/index.js",

src/index.d.ts

 declare global {
-    type Only<T, C, R> = T extends C ? R : never
     type Option<T> = null | undefined | T
+    type Either<L, R> = { left: L } | { right: R } // use right to represent a correct value, left for errors
 }
@@ -10,1 +10,6 @@
 export function isSome<T>(option: Option<T>): option is T
+
+export function expectLeft<L, R>(either: Either<L, R>, msg?: string): L
+export function expectRight<L, R>(either: Either<L, R>, msg?: string): R
+export function isLeft<L, R>(either: Either<L, R>): either is { left: L }
+export function isRight<L, R>(either: Either<L, R>): either is { right: R }

src/index.js

@@ -12,3 +12,6 @@ /**
  */
-export function expectSome(option, msg = `unexpected ${option}`) {
+export function expectSome(
+    option,
+    msg = `expected Option.some, got ${option}`
+) {
     if (option !== null && option !== undefined) {
@@ -38,1 +41,57 @@ return option
 }
+
+/**
+ * @template L
+ * @template R
+ * @param {Either<L, R>} either
+ * @param {string} msg
+ * @returns {L}
+ */
+export function expectLeft(
+    either,
+    msg = `expected Either.left, got ${either}`
+) {
+    if ("left" in either) {
+        return either.left
+    } else {
+        throw new Error(msg)
+    }
+}
+
+/**
+ * @template L
+ * @template R
+ * @param {Either<L, R>} either
+ * @param {string} msg
+ * @returns {R}
+ */
+export function expectRight(
+    either,
+    msg = `expected Either.right, got ${either}`
+) {
+    if ("right" in either) {
+        return either.right
+    } else {
+        throw new Error(msg)
+    }
+}
+
+/**
+ * @template L
+ * @template R
+ * @param {Either<L, R>} either
+ * @returns {either is {left: L}}
+ */
+export function isLeft(either) {
+    return "left" in either
+}
+
+/**
+ * @template L
+ * @template R
+ * @param {Either<L, R>} either
+ * @returns {either is {right: R}}
+ */
+export function isRight(either) {
+    return "right" in either
+}

No alert changes

Improved metrics

Total package byte prevSize

5105

increased by35.55%

Lines of code

116

increased by103.51%

No dependency changes