Merge 308e6e0 into 77ffb2b

Author: joelnet

README.md

@@ -1,4 +1,4 @@
-# MojiScript ![project:experimental](https://img.shields.io/badge/project-experimental-orange.svg) [![build status](https://travis-ci.org/joelnet/MojiScript.svg?branch=master)](https://travis-ci.org/joelnet/MojiScript) [![Coverage Status](https://coveralls.io/repos/github/joelnet/MojiScript/badge.svg?branch=master&v=1)](https://coveralls.io/github/joelnet/MojiScript?branch=master) ![project:experimental](https://img.shields.io/badge/tests-354-green.svg) [![All Contributors](https://img.shields.io/badge/all_contributors-19-orange.svg?style=flat-square)](#contributors)
+# MojiScript ![project:experimental](https://img.shields.io/badge/project-experimental-orange.svg) [![build status](https://travis-ci.org/joelnet/MojiScript.svg?branch=master)](https://travis-ci.org/joelnet/MojiScript) [![Coverage Status](https://coveralls.io/repos/github/joelnet/MojiScript/badge.svg?branch=master&v=1)](https://coveralls.io/github/joelnet/MojiScript?branch=master) ![project:experimental](https://img.shields.io/badge/tests-356-green.svg) [![All Contributors](https://img.shields.io/badge/all_contributors-19-orange.svg?style=flat-square)](#contributors)
 
 ![MojiScript logo](https://raw.githubusercontent.com/joelnet/MojiScript/master/media/MS_logo_64.png)
 

type/Either.js

@@ -15,10 +15,20 @@ const fromEither = def => either => isRight(either) ? either.value : def
 // fromNullable :: Any -> Either
 const fromNullable = value => value == null ? Left(value) : Right(value)
 
+// try :: Thunk -> Maybe
+const maybeTry = thunk => {
+  try {
+    return Right(thunk())
+  } catch (err) {
+    return Left(err)
+  }
+}
+
 module.exports['@@type'] = typeEither
 module.exports.fromFalsy = fromFalsy
 module.exports.fromEither = fromEither
 module.exports.fromNullable = fromNullable
+module.exports.try = maybeTry
 
 // Experimental debug code
 /* istanbul ignore next */

type/Left.js

@@ -1,6 +1,7 @@
 const is = require('./is')
 const { typeLeft } = require('./_allTypes')
 
+const isError = is(Error)
 const isFunction = is(Function)
 
 // Left :: Any -> Left
@@ -47,7 +48,13 @@ const prototype = {
   leftFlatMap,
   'fantasy-land/ap': ap,
   'fantasy-land/map': map,
-  inspect() { return `Left (${isFunction(this.value) ? `function ${this.value.name}()` : JSON.stringify(this.value)})` }
+  inspect() {
+    const value =
+      isFunction(this.value) ? `function ${this.value.name}()`
+      : isError(this.value) ? `[ Error: ${this.value.message} ]`
+      : JSON.stringify(this.value)
+    return `Left (${value})`
+  }
 }
 
 Left['@@type'] = typeLeft

type/Maybe.js

@@ -15,10 +15,15 @@ const fromMaybe = def => maybe => isJust(maybe) ? maybe.value : def
 // fromNullable :: Any -> Maybe
 const fromNullable = value => value == null ? Nothing : Just(value)
 
+// unlift :: Function -> Array -> Any
+const unlift = func => (...args) =>
+  func(...args.map(fromNullable)).value
+
 module.exports['@@type'] = typeMaybe
 module.exports.fromFalsy = fromFalsy
 module.exports.fromMaybe = fromMaybe
 module.exports.fromNullable = fromNullable
+module.exports.unlift = unlift
 
 // Experimental debug code
 /* istanbul ignore next */

type/Right.js

@@ -1,6 +1,7 @@
 const is = require('./is')
 const { typeRight } = require('./_allTypes')
 
+const isError = is(Error)
 const isFunction = is(Function)
 
 // Right :: Any -> Right
@@ -47,7 +48,14 @@ const prototype = {
   leftFlatMap,
   'fantasy-land/ap': ap,
   'fantasy-land/map': map,
-  inspect() { return `Right (${isFunction(this.value) ? `function ${this.value.name}()` : JSON.stringify(this.value)})` }
+  inspect() {
+    const value =
+      isFunction(this.value) ? `function ${this.value.name}()`
+      : isError(this.value) ? `[ Error: ${this.value.message} ]`
+      : JSON.stringify(this.value)
+
+    return `Right (${value})`
+  }
 }
 
 Right['@@type'] = typeRight

type/__tests__/Either.test.js

@@ -1,7 +1,8 @@
 const is = require('../is')
 const Right = require('../Right')
 const Left = require('../Left')
-const { fromFalsy, fromNullable, fromEither } = require('../Either')
+const Either = require('../Either')
+const { fromFalsy, fromNullable, fromEither } = Either
 
 describe('Either', () => {
   describe('fromFalsy', () => {
@@ -121,4 +122,18 @@ describe('Either', () => {
       expect(actual).toBe(expected)
     })
   })
+
+  describe('try', () => {
+    test('success returns Right', () => {
+      const expected = Right(123)
+      const actual = Either.try(() => 123)
+      expect(actual).toMatchObject(expected)
+    })
+
+    test('error returns Left', () => {
+      const expected = Left(Error('UH OH'))
+      const actual = Either.try(() => { throw Error('UH OH')})
+      expect(actual).toMatchObject(expected)
+    })
+  })
 })

type/__tests__/Left.test.js

@@ -105,6 +105,13 @@ describe('type/Left', () => {
     expect(actual).toEqual(expected)
   })
 
+  test('Left(Error).inspect', () => {
+    expect.assertions(1)
+    const expected = 'Left ([ Error: UH OH ])'
+    const actual = Left(Error('UH OH')).inspect()
+    expect(actual).toEqual(expected)
+  })
+
   test('Left(add()).inspect', () => {
     expect.assertions(1)
     const add = () => {}

type/__tests__/Maybe.test.js

@@ -1,8 +1,10 @@
 const is = require('../is')
 const Just = require('../Just')
-const { fromFalsy, fromNullable, fromMaybe } = require('../Maybe')
+const { fromFalsy, fromNullable, fromMaybe, unlift } = require('../Maybe')
 const Nothing = require('../Nothing')
 
+const toStringMaybe = maybe => maybe.map(value => value.toUpperCase())
+
 describe('Maybe', () => {
   describe('fromFalsy', () => {
     test('null is Nothing', () => {
@@ -121,4 +123,18 @@ describe('Maybe', () => {
       expect(actual).toBe(expected)
     })
   })
+
+  describe('unlift', () => {
+    test('Just', () => {
+      const expected = "ABC"
+      const actual = unlift(toStringMaybe)("abc")
+      expect(actual).toBe(expected)
+    })
+
+    test('Nothing', () => {
+      const expected = null
+      const actual = unlift(toStringMaybe)(null)
+      expect(actual).toBe(expected)
+    })
+  })
 })

type/__tests__/Right.test.js

@@ -84,6 +84,13 @@ describe('type/Right', () => {
     expect(actual).toEqual(expected)
   })
 
+  test('Right(function()).inspect', () => {
+    expect.assertions(1)
+    const expected = 'Right ([ Error: UH OH ])'
+    const actual = Right(Error('UH OH')).inspect()
+    expect(actual).toEqual(expected)
+  })
+
   test('Right(add()).inspect', () => {
     expect.assertions(1)
     const add = () => {}