Add 'sum-types/caseof-eq'

.gitignore

@@ -1 +1,2 @@
 /index.js
+/caseof-eq.js

.travis.yml

@@ -1,4 +1,7 @@
 language: node_js
-node_js:
-  - "6"
-  - "4"
+node_js: [4, 6]
+install:
+  - npm install --global yarn
+  - yarn install
+script:
+  - npm run test

CHANGELOG.md

@@ -3,6 +3,10 @@
 All notable changes to this project will be documented in this file.
 This project adheres to [Semantic Versioning](http://semver.org/).
 
+## 0.9.3 - 2016-11-11
+### Added
+- `sum-types/caseof-eq` for matching for equality.
+
 ## 0.9.2 - 2016-09-12
 ### Fixed
 - Fixed thrown exception in Safari.

README.md

@@ -22,12 +22,14 @@ Install from NPM
 ~~~
 npm install --save sum-types
 ~~~
-and import the module
+
+### `import 'sum-types'`
+
 ~~~js
 import {makeSum, caseof} from 'sum-types'
 ~~~
 
-### `makeSum()`
+#### `makeSum()`
 
 Creates an map of constructor functions from constructor definitions
 
@@ -73,7 +75,7 @@ b.bar === 1
 ~~~
 
 
-### `caseof()`
+#### `caseof()`
 
 The `caseof()` function accepts to arguments. The first is the value to be
 matched and the second is a list of constructor-function pairs. The function
@@ -113,6 +115,32 @@ caseof(value, [
 ~~~
 
 
+
+### `import 'sum-types/caseof-eq'`
+
+_Added in v0.9.3_
+
+~~~js
+import {caseof, otherwise} from 'sum-types/caseof-eq'
+~~~
+
+The `caseof()` function matches against patterns using strict equality (`===`).
+
+~~~js
+const result = caseof(value, [
+  ['A', () => 'a'],
+  ['B', 'C', () => 'bc'],
+  [otherwise, () => 'otherwise'],
+])
+~~~
+
+If the value is `A` the result will be `a`. If the value is either `B` or `C`
+the result will be `bc`. In all other cases the result will be `otherwise`.
+
+Note that the syntax is slightly different from the main `caseof()`: Multiple
+patterns are not wrapped in an array.
+
+
 Motivation
 ----------
 

package.json

@@ -1,12 +1,17 @@
 {
   "name": "sum-types",
-  "version": "0.9.2",
+  "version": "0.9.3",
   "description": "Introduction and eliminiation of sum types (or tagged unions)",
   "main": "index.js",
   "scripts": {
-    "prepublish": "babel index.es6.js --out-file index.js",
-    "test": "eslint index.es6.js test && mocha test"
+    "prepublish": "babel --out-dir . src",
+    "test": "eslint src test && mocha test"
   },
+  "files": [
+    "src",
+    "index.js",
+    "caseof-eq.js"
+  ],
   "keywords": [
     "data",
     "functional",

src/caseof-eq.js

@@ -0,0 +1,14 @@
+export function caseof (target, cases) {
+  for (const i in cases) {
+    const patterns = cases[i].slice()
+    const handler = patterns.pop()
+    const matches = patterns.some((p) => p === target || p === otherwise)
+    if (matches) {
+      return handler(target)
+    }
+  }
+
+  throw new Error('Unmatched case for ' + target)
+}
+
+export const otherwise = {}

test/caseof-eq.test.js

@@ -0,0 +1,25 @@
+import {otherwise, caseof} from '../src/caseof-eq.js'
+import assert from 'assert'
+
+describe('#caseof() with equality match', function () {
+  it('matches correct case', function () {
+    const cases = [
+      ['A', () => 'A'],
+      ['B', () => 'B'],
+      ['C', 'D', () => 'CD'],
+      [otherwise, () => null],
+    ]
+
+    assert.equal(caseof('A', cases), 'A')
+    assert.equal(caseof('B', cases), 'B')
+    assert.equal(caseof('C', cases), 'CD')
+    assert.equal(caseof('D', cases), 'CD')
+    assert.equal(caseof('X', cases), null)
+  })
+
+  it('throws for unmatched target', function () {
+    assert.throws(() => {
+      caseof('A', [['B', () => null]])
+    }, /Unmatched case for/)
+  })
+})

test/test.js

@@ -1,4 +1,4 @@
-import {makeSum, caseof} from '../index.es6.js'
+import {makeSum, caseof} from '../src/index.js'
 import assert from 'assert'
 
 describe('#makeSum() value', function () {