From e5e7ae8c8ad8c7f9fd234d7919d3ae08f4f46c9e Mon Sep 17 00:00:00 2001
From: yazeedb <ybzadough@gmail.com>
Date: Wed, 18 Apr 2018 20:45:32 -0400
Subject: [PATCH] add snippet

---
 snippets/when.md | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 snippets/when.md

diff --git a/snippets/when.md b/snippets/when.md
new file mode 100644
index 000000000..16dbe9a54
--- /dev/null
+++ b/snippets/when.md
@@ -0,0 +1,18 @@
+### when
+
+Tests a value, `x`, against a predicate function. If `true`, return `fn(x)`. Else, return `x`.
+`when(pred, whenTrue)` returns another function expecting `x` for better composability.
+
+```js
+const when = (pred, whenTrue) => (x) => pred(x) ? whenTrue(x) : x;
+```
+
+```js
+const doubleEvenNumbers = when(
+  (x) => x % 2 === 0,
+  (x) => x * 2
+);
+
+doubleEvenNumbers(2) // 4
+doubleEvenNumbers(1) // 1
+```