no commit message

Author: guy-borderless

deno.json

@@ -6,7 +6,6 @@
     "noImplicitOverride": true,
     "noUncheckedIndexedAccess": true
   },
-<<<<<<< HEAD
   "imports": {
     "@deno/doc": "jsr:@deno/doc@0.137",
     "@deno/graph": "jsr:@deno/graph@^0.74",
@@ -53,9 +52,6 @@
     "graphviz": "npm:node-graphviz@^0.1.1",
     "npm:/typescript": "npm:typescript@5.4.4"
   },
-=======
-  "importMap": "./import_map.json",
->>>>>>> 05b6d7eedd8e441cb8fa22078f377a6a37b4fa88
   "tasks": {
     "test": "deno test --unstable-http --unstable-webgpu --doc --allow-all --parallel --coverage --trace-leaks --clean",
     "test:browser": "git grep --name-only \"This module is browser compatible.\" | grep -v deno.json | grep -v .github/workflows | grep -v _tools | grep -v encoding/README.md | grep -v media_types/vendor/update.ts | xargs deno check --config browser-compat.tsconfig.json",

functions/curry.ts

@@ -3,7 +3,6 @@
   "version": "0.1.0",
   "exports": {
     ".": "./mod.ts",
-    "./curry": "./curry.ts",
     "./pipe": "./pipe.ts"
   }
 }

functions/deno.json

@@ -28,5 +28,4 @@
  * @module
  */
 
-export * from "./curry.ts";
 export * from "./pipe.ts";

functions/mod.ts

@@ -17,15 +17,19 @@ type PipeArgs<F extends AnyFunc[], Acc extends AnyFunc[] = []> = F extends [
     : Acc
   : Acc;
 
+export function pipe(): <T>(arg: T) => T;
 export function pipe<FirstFn extends AnyFunc, F extends AnyFunc[]>(
   firstFn: FirstFn,
   ...fns: PipeArgs<F> extends F ? F : PipeArgs<F>
-): (arg: Parameters<FirstFn>[0]) => LastFnReturnType<F, ReturnType<FirstFn>> {
+): (arg: Parameters<FirstFn>[0]) => LastFnReturnType<F, ReturnType<FirstFn>>;
+
+export function pipe<FirstFn extends AnyFunc, F extends AnyFunc[]>(
+  firstFn?: FirstFn,
+  ...fns: PipeArgs<F> extends F ? F : PipeArgs<F>
+): any {
+  if (!firstFn) {
+    return <T>(arg: T) => arg;
+  }
   return (arg: Parameters<FirstFn>[0]) =>
     (fns as AnyFunc[]).reduce((acc, fn) => fn(acc), firstFn(arg));
 }
-
-if (import.meta.main) {
-  const res = pipe(Math.abs, Math.sqrt, Math.floor);
-  res(-2); // 1
-}

functions/pipe.ts

@@ -0,0 +1,32 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+
+import { assertEquals, assertThrows } from "@std/assert";
+import { pipe } from "./mod.ts";
+
+Deno.test("pipe() handles mixed types", () => {
+  const inputPipe = pipe(
+    Math.abs,
+    Math.sqrt,
+    Math.floor,
+    (num) => `result: ${num}`,
+  );
+  assertEquals(inputPipe(-2), "result: 1");
+});
+
+Deno.test("en empty pipe is the identity function", () => {
+  const inputPipe = pipe();
+  assertEquals(inputPipe("hello"), "hello");
+});
+
+Deno.test("pipe() throws an exceptions when a function throws an exception", () => {
+  const inputPipe = pipe(
+    Math.abs,
+    Math.sqrt,
+    Math.floor,
+    (num) => {
+      throw new Error("This is an error for " + num);
+    },
+    (num) => `result: ${num}`,
+  );
+  assertThrows(() => inputPipe(-2));
+});