pluck

README.md

@@ -9,7 +9,7 @@
 <p align="center">
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-  <a href="#"><img src="https://img.shields.io/badge/gzip--size-1.44%20kB-blue.svg" alt="gzip-size" style="max-width:100%;"></a>
+  <a href="#"><img src="https://img.shields.io/badge/gzip--size-1.45%20kB-blue.svg" alt="gzip-size" style="max-width:100%;"></a>
   <br />
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@@ -117,6 +117,7 @@ If you've lived with FP long enough, you are likely familiar with most of the fu
 | `pick` | `[k] -> { k: v } -> { k: v }` |
 | `pipe` | `((a -> b), ..., (y -> z)) -> a -> z` |
 | `pipeP` | `((a -> Promise b), ..., (y -> Promise z)) -> a -> Promise z` |
+| `pluck` | `k -> [{ k: v }] -> [v]` |
 | `prepend` | `a -> [a] -> [a]` |
 | `prop` | `k -> { k: v } -> v` |
 | `propEq` | `k -> v -> { k: v } -> Boolean` |

src.js

@@ -353,6 +353,11 @@ const pipeP = unapply(flip(reduce(flip(then))))
 // cond :: [[(a -> Boolean), (a -> b)]] -> a -> b
 const cond = compose(reduceRight(thrush, unit), map(apply(ifElse)))
 
+// pluck :: k -> [{ k: v }] -> [v]
+const pluck = curry((key, list) =>
+  map(prop(key), list)
+)
+
 // slice :: Number -> Number -> [a] -> [a]
 const slice = curry((from, to, list) =>
   list.slice(from, to)
@@ -427,6 +432,7 @@ _assign(exports, {
   pick,
   pipe,
   pipeP,
+  pluck,
   prepend,
   prop,
   propEq,

test/pluck.js

@@ -0,0 +1,15 @@
+const { expect } = require('chai')
+
+const { pluck } = require('..')
+
+describe('pluck', () => {
+  const list = [{ a: 'b' }, { a: 'c' }, { b: 'a' }]
+
+  it('plucks the values from a list for a given key', () =>
+    expect(pluck('a', list)).to.eql(['b', 'c', undefined])
+  )
+
+  it('is curried', () =>
+    expect(pluck('a')(list)).to.eql(['b', 'c', undefined])
+  )
+})