From 3010b42fbc1f5b6be60c7d44657145d6fb0592b3 Mon Sep 17 00:00:00 2001
From: Andrei Dumitrescu <5057797+andreidcm@users.noreply.github.com>
Date: Thu, 1 Oct 2020 14:19:21 +0200
Subject: [PATCH] feat: Update "when" to pipe when passing array of functions.
 Add uncurried version.

BREAKING CHANGE:

No longer accepts primitive values for thenFn or elseFn parameters.

// old
when(isTrue, "val is true", "value is not true", true)

// new
when(isTrue, () => "val is true", same("value is not true"), true)
---
 src/when/when.js      | 28 +++++++++++++++++++++-------
 src/when/when.test.js | 42 ++++++++++++++++++++++++++++++------------
 2 files changed, 51 insertions(+), 19 deletions(-)

diff --git a/src/when/when.js b/src/when/when.js
index b9e22df..4bf93df 100644
--- a/src/when/when.js
+++ b/src/when/when.js
@@ -1,4 +1,13 @@
-import { is } from "../is/is"
+import { pipe } from "../pipe/pipe"
+import { i } from "../i/i"
+
+const _when = (_ifFn, _thenFn, _elseFn = i, source) => {
+  const ifFn = Array.isArray(_ifFn) ? pipe(..._ifFn) : _ifFn
+  const thenFn = Array.isArray(_thenFn) ? pipe(..._thenFn) : _thenFn
+  const elseFn = Array.isArray(_elseFn) ? pipe(..._elseFn) : _elseFn
+
+  return ifFn(source) ? thenFn(source) : elseFn(source)
+}
 
 /**
  * Functional if-then-else
@@ -11,7 +20,9 @@ import { is } from "../is/is"
  * @return {mixed}
  *
  * @tag Core
+ * @signature (ifFn: Function, thenFn: Function, elseFn: Function, source: mixed): mixed
  * @signature (ifFn: Function, thenFn: Function, elseFn: Function) => (source: mixed): mixed
+ * @signature (ifFn: Function, thenFn: Function) => (source: mixed): mixed
  *
  * @example
  * when(isEven, increment, decrement)(5)
@@ -20,14 +31,17 @@ import { is } from "../is/is"
  * when(isOdd, increment)(6)
  * // => 6
  */
-export const when = (ifFn, thenFn, elseFn) => source => {
-  if (ifFn(source)) {
-    return typeof thenFn === "function" ? thenFn(source) : thenFn
+export const when = (...params) => {
+  // @signature (ifFn, thenFn) => (source)
+  if (params.length <= 2) {
+    return source => _when(params[0], params[1], undefined, source)
   }
 
-  if (typeof elseFn === "function") {
-    return elseFn(source)
+  // @signature (ifFn, thenFn, elseFn) => (source)
+  if (params.length <= 3) {
+    return source => _when(params[0], params[1], params[2], source)
   }
 
-  return is(elseFn) ? elseFn : source
+  // @signature (ifFn, thenFn, elseFn, source)
+  return _when(...params)
 }
diff --git a/src/when/when.test.js b/src/when/when.test.js
index c92a58a..23a223c 100644
--- a/src/when/when.test.js
+++ b/src/when/when.test.js
@@ -5,21 +5,15 @@ const isEven = source => source % 2 !== 0
 
 test("when", t => {
   t.equals(
-    when(isEven, "even", "odd")(5),
-    "even",
-    "Primitive instead of then function"
-  )
-
-  t.equals(
-    when(isEven, "even", "odd")(6),
-    "odd",
-    "Primitive instead of else function"
+    when(isEven, inc, dec)(5),
+    6,
+    'Increment even input with "then" & "else" defined (curried)'
   )
 
   t.equals(
-    when(isEven, inc, dec)(5),
+    when(isEven, inc, dec, 5),
     6,
-    'Increment even input with "then" & "else" defined'
+    'Increment even input with "then" & "else" defined (uncurried)'
   )
 
   t.equals(
@@ -28,10 +22,34 @@ test("when", t => {
     'Decrement odd input with "then" & "else" defined'
   )
 
+  t.equals(
+    when(isEven, [inc, inc], dec)(5),
+    7,
+    'Run "then" as a pipe array of functions'
+  )
+
+  t.equals(
+    when(isEven, inc, [dec, dec])(6),
+    4,
+    'Run "else" as a pipe array of functions'
+  )
+
+  t.equals(
+    when([inc, isEven], inc, dec)(4),
+    5,
+    'Run "if" as a pipe array of functions'
+  )
+
   t.equals(
     when(isEven, inc)(5),
     6,
-    'Increment even input with only "then" defined'
+    'Increment even input with only "then" defined (curried)'
+  )
+
+  t.equals(
+    when(isEven, inc)(6),
+    6,
+    'Return same input when "if" is false with only "then" defined'
   )
 
   t.equals(