feat: 🎸 add pipe utility

same as ramda's pipe
dmitriz · Dec 23, 2022 · 7ab965f · 7ab965f
1 parent 5aaf21e
commit 7ab965f
Show file tree

Hide file tree

Showing 2 changed files with 50 additions and 2 deletions.
diff --git a/index.js b/index.js
@@ -6,7 +6,7 @@ const curry2 = f => (...a) => (...b) => f(...a, ...b)
 
 /**
  * Pass tuple of values to sequence of functions similar to UNIX pipe
- * `(x1, ..., xn) | f1 | f2 | ... | fm`
+ * `(x1, ..., xn) | f1 | f2 | ... | fm`.
  *
  * @param {...*} args - tuple of arbitrary values.
  * @param {...Function} fns - functions `(f1, f2, ..., fn)`.
@@ -24,6 +24,20 @@ const pipeline = (...args) => (...fns) => fns.slice(1).reduce(
   fns[0](...args)
 )
 
+/**
+ * Compose functions left to right as in ramda's `pipe`.
+ * 
+ * @param {...Function} fns - functions `(f1, f2, ..., fn)`.
+ * @returns {*} `pipe(...fns)`
+ *    - Composite function `(...args) => fn(...f2(f1(...args))...)`.
+ * 
+ * @example
+ * pipe((a,b)=>a+b, x=>x*2)
+ *   // is equivalent to
+ * (a,b)=>(a+b)*2
+ * 
+ */
+const pipe = (...fns) => (...args) => pipeline(...args)(...fns)
 
 
 /* ----- CPS operators ----- */
@@ -318,6 +332,6 @@ const node2cps = nodeApi => (...args) => CPS(
 )
 
 module.exports = {
-  curry2, pipeline,
+  curry2, pipeline, pipe,
   of, ofN, map, chain, filter, scan, scanS, ap, lift2, CPS, node2cps
 }
diff --git a/test/pipe.test.js b/test/pipe.test.js
@@ -0,0 +1,34 @@
+const test = require('./config')
+const { pipe } = require('..')
+
+test('pass single argument to single function', t => {
+	t.is(pipe(x => x + 2)(1), 3)
+})
+
+test('pass multiple arguments to single function', t => {
+	t.is(pipe(
+		(x, y) => x + y
+	)(1, 5), 6)
+	t.is(pipe(
+		(x, y, z) => x + y - z
+	)(1, 2, 5), -2)
+})
+
+test('chain multiple functions with single argument', t => {
+	t.is(pipe(
+		x => x + 1,
+		y => y - 2
+	)(2), 1)
+	t.is(pipe(
+		x => x + 1,
+		y => y - 2,
+		z => z * 2
+	)(2), 2)
+})
+
+test('chain multiple functions with multiple args', t => {
+	t.is(pipe(
+		(x, y) => x + y,
+		z => z * 2
+	)(1, 3), 8)
+})