From cdc08ac78d7f1f1c27ec51ffc7d36eb2c14ca685 Mon Sep 17 00:00:00 2001
From: Stefano Vozza <svozza@gmail.com>
Date: Thu, 11 Feb 2016 21:08:07 +0000
Subject: [PATCH] modularise includes, init, last and length

---
 includes.js      |  3 +++
 index.js         | 12 ++++++++----
 init.js          |  1 +
 last.js          |  1 +
 length.js        |  1 +
 test/includes.js | 18 ++++++++++++++++++
 test/init.js     | 16 ++++++++++++++++
 test/last.js     | 10 ++++++++++
 test/length.js   | 10 ++++++++++
 9 files changed, 68 insertions(+), 4 deletions(-)
 create mode 100644 includes.js
 create mode 100644 init.js
 create mode 100644 last.js
 create mode 100644 length.js
 create mode 100644 test/includes.js
 create mode 100644 test/init.js
 create mode 100644 test/last.js
 create mode 100644 test/length.js

diff --git a/includes.js b/includes.js
new file mode 100644
index 0000000..07ac139
--- /dev/null
+++ b/includes.js
@@ -0,0 +1,3 @@
+const curry = require('./curry')
+
+module.exports = curry((e, xs) => xs.indexOf(e) !== -1)
diff --git a/index.js b/index.js
index f40fdce..443fa8c 100644
--- a/index.js
+++ b/index.js
@@ -9,6 +9,10 @@ const curry = require('./curry')
 const append = require('./append')
 const drop = require('./drop')
 const head = require('./head')
+const includes = require('./includes')
+const init = require('./init')
+const last = require('./last')
+const length = require('./length')
 
 const f2 = curry((name, arg, coll) => {
   return coll[name](arg)
@@ -23,10 +27,10 @@ arg2.forEach(name => ex[name] = f3(name))
 ex.append = append
 ex.drop = drop
 ex.head = head
-ex.includes = curry((e, list) => list.indexOf(e) !== -1)
-ex.init = list => list.slice(0, list.length - 1)
-ex.last = list => list[list.length -1]
-ex.length = list => list.length
+ex.includes = includes
+ex.init = init
+ex.last = last
+ex.length = length
 ex.nth = curry((i, list) => list[i])
 ex.pluck = curry((key, list) => list.map(o => o[key]))
 ex.range = curry((start, end) => Array(end - start).fill(1).map((e, i) => i + start))
diff --git a/init.js b/init.js
new file mode 100644
index 0000000..431992b
--- /dev/null
+++ b/init.js
@@ -0,0 +1 @@
+module.exports = xs => xs.slice(0, xs.length - 1)
diff --git a/last.js b/last.js
new file mode 100644
index 0000000..ef92881
--- /dev/null
+++ b/last.js
@@ -0,0 +1 @@
+module.exports = xs => xs[xs.length - 1]
\ No newline at end of file
diff --git a/length.js b/length.js
new file mode 100644
index 0000000..aaf614f
--- /dev/null
+++ b/length.js
@@ -0,0 +1 @@
+module.exports = xs => xs.length
\ No newline at end of file
diff --git a/test/includes.js b/test/includes.js
new file mode 100644
index 0000000..69743bd
--- /dev/null
+++ b/test/includes.js
@@ -0,0 +1,18 @@
+const assert = require('assert')
+const includes = require('../includes.js')
+
+describe('includes', () => {
+
+  it('is curried', () => {
+    assert.strictEqual(includes(1)([1, 2, 3, 4]), true)
+  })
+
+  it('should indicate if the element is in the list', () => {
+    assert.strictEqual(includes(1, [1, 2, 3, 4]), true)
+  })
+
+  it('should indicate if the element is not in the list', () => {
+    assert.strictEqual(includes(5, [1, 2, 3, 4]), false)
+  })
+
+})
\ No newline at end of file
diff --git a/test/init.js b/test/init.js
new file mode 100644
index 0000000..a3dad23
--- /dev/null
+++ b/test/init.js
@@ -0,0 +1,16 @@
+const assert = require('assert')
+const init = require('../init.js')
+
+describe('init', () => {
+
+  it('does not mutate the original list', () => {
+    const xs = [1, 2, 3, 4]
+    const initxs = init(xs)
+    assert.notStrictEqual(xs, initxs)
+  })
+
+  it('should remove the last item of the list', () => {
+    assert.deepEqual(init([1, 2, 3, 4, 5]), [1, 2, 3, 4])
+  })
+
+})
\ No newline at end of file
diff --git a/test/last.js b/test/last.js
new file mode 100644
index 0000000..c9dc81b
--- /dev/null
+++ b/test/last.js
@@ -0,0 +1,10 @@
+const assert = require('assert')
+const last = require('../last.js')
+
+describe('last', () => {
+
+  it('should retrieve last item in a list', () => {
+    assert.strictEqual(last([1, 2, 3, 4, 5]), 5)
+  })
+
+})
\ No newline at end of file
diff --git a/test/length.js b/test/length.js
new file mode 100644
index 0000000..8e9f441
--- /dev/null
+++ b/test/length.js
@@ -0,0 +1,10 @@
+const assert = require('assert')
+const length = require('../length.js')
+
+describe('length', () => {
+
+  it('should return the length of a list', () => {
+    assert.strictEqual(length([1, 2, 3, 4, 5]), 5)
+  })
+
+})
\ No newline at end of file