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add maybeToList and maybeToArray transformations
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,43 @@ | ||
| /** @license ISC License (c) copyright 2019 original and current authors */ | ||
| /** @author Ian Hofmann-Hicks (evil) */ | ||
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| const List = require('.') | ||
| const Maybe = require('../core/types').proxy('Maybe') | ||
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| const curry = require('../core/curry') | ||
| const isFunction = require('../core/isFunction') | ||
| const isSameType = require('../core/isSameType') | ||
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| const applyTransform = maybe => | ||
| maybe.either( | ||
| List.empty, | ||
| List.of | ||
| ) | ||
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| const err = | ||
| 'maybeToList: Argument must be a Maybe instanstace or a Maybe returning function' | ||
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| // maybeToList : Maybe a -> List a | ||
| // maybeToList : (a -> Maybe b) -> a -> List b | ||
| function maybeToList(maybe) { | ||
| if(isFunction(maybe)) { | ||
| return function(x) { | ||
| const m = maybe(x) | ||
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| if(!isSameType(Maybe, m)) { | ||
| throw new TypeError(err) | ||
| } | ||
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| return applyTransform(m) | ||
| } | ||
| } | ||
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| if(isSameType(Maybe, maybe)) { | ||
| return applyTransform(maybe) | ||
| } | ||
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| throw new TypeError(err) | ||
| } | ||
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| module.exports = curry(maybeToList) | ||
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|
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,83 @@ | ||
| const test = require('tape') | ||
| const helpers = require('../test/helpers') | ||
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| const bindFunc = helpers.bindFunc | ||
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| const List = require('.') | ||
| const Maybe = require('../core/Maybe') | ||
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| const isFunction = require('../core/isFunction') | ||
| const isSameType = require('../core/isSameType') | ||
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| const identity = x => x | ||
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| const maybeToList = require('./maybeToList') | ||
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| test('maybeToList transform', t => { | ||
| const f = bindFunc(maybeToList) | ||
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| t.ok(isFunction(maybeToList), 'is a function') | ||
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| const err = /maybeToList: Argument must be a Maybe instanstace or a Maybe returning function/ | ||
| t.throws(f(undefined), err, 'throws if first arg is undefined') | ||
| t.throws(f(null), err, 'throws if first arg is null') | ||
| t.throws(f(0), err, 'throws if first arg is a falsey number') | ||
| t.throws(f(1), err, 'throws if first arg is a truthy number') | ||
| t.throws(f(''), err, 'throws if first arg is a falsey string') | ||
| t.throws(f('string'), err, 'throws if first arg is a truthy string') | ||
| t.throws(f(false), err, 'throws if first arg is false') | ||
| t.throws(f(true), err, 'throws if first arg is true') | ||
| t.throws(f([]), err, 'throws if first arg is an array') | ||
| t.throws(f({}), err, 'throws if first arg is an object') | ||
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| t.end() | ||
| }) | ||
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| test('maybeToList with Maybe', t => { | ||
| const some = 'something' | ||
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| const good = maybeToList(Maybe.Just(some)) | ||
| const bad = maybeToList(Maybe.Nothing()) | ||
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| t.ok(isSameType(List, good), 'returns a List with a Just') | ||
| t.ok(isSameType(List, bad), 'returns a List with a Nothing') | ||
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| t.ok(good.equals(List.of(some)), 'Just maps to single item List containing the value') | ||
| t.ok(bad.equals(List.empty()), 'Nothing maps to an empty List') | ||
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| t.end() | ||
| }) | ||
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| test('maybeToList with Maybe returning function', t => { | ||
| const some = 'something' | ||
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| t.ok(isFunction(maybeToList(Maybe.of)), 'returns a function') | ||
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| const f = bindFunc(maybeToList(identity)) | ||
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| const err = /maybeToList: Argument must be a Maybe instanstace or a Maybe returning function/ | ||
| t.throws(f(undefined), err, 'throws if function returns undefined') | ||
| t.throws(f(null), err, 'throws if function returns null') | ||
| t.throws(f(0), err, 'throws if function returns a falsey number') | ||
| t.throws(f(1), err, 'throws if function returns a truthy number') | ||
| t.throws(f(''), err, 'throws if function returns a falsey string') | ||
| t.throws(f('string'), err, 'throws if function returns a truthy string') | ||
| t.throws(f(false), err, 'throws if function returns false') | ||
| t.throws(f(true), err, 'throws if function returns true') | ||
| t.throws(f([]), err, 'throws if function returns an array') | ||
| t.throws(f({}), err, 'throws if function returns an object') | ||
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| const lift = | ||
| x => x !== undefined ? Maybe.Just(x) : Maybe.Nothing() | ||
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| const good = maybeToList(lift, some) | ||
| const bad = maybeToList(lift, undefined) | ||
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| t.ok(isSameType(List, good), 'returns a List with a Just') | ||
| t.ok(isSameType(List, bad), 'returns a List with a Nothing') | ||
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| t.ok(good.equals(List.of(some)), 'Just maps to single item List containing the value') | ||
| t.ok(bad.equals(List.empty()), 'Nothing maps to an empty List') | ||
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| t.end() | ||
| }) |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,35 @@ | ||
| /** @license ISC License (c) copyright 2019 original and current authors */ | ||
| /** @author Ian Hofmann-Hicks (evil) */ | ||
|
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| const Maybe = require('.') | ||
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| const curry = require('../core/curry') | ||
| const isFunction = require('../core/isFunction') | ||
| const isSameType = require('../core/isSameType') | ||
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| const applyTransform = maybe => | ||
| maybe.either(() => [], x => [ x ]) | ||
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| const err = | ||
| 'maybeToArray: Argument must be a Maybe instanstace or a Maybe returning function' | ||
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| function maybeToArray(maybe) { | ||
| if(isFunction(maybe)) { | ||
| return function(x) { | ||
| const m = maybe(x) | ||
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| if(!isSameType(Maybe, m)) { | ||
| throw new TypeError(err) | ||
| } | ||
| return applyTransform(m) | ||
| } | ||
| } | ||
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| if(isSameType(Maybe, maybe)) { | ||
| return applyTransform(maybe) | ||
| } | ||
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| throw new TypeError(err) | ||
| } | ||
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| module.exports = curry(maybeToArray) |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,82 @@ | ||
| const test = require('tape') | ||
| const helpers = require('../test/helpers') | ||
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| const bindFunc = helpers.bindFunc | ||
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| const Maybe = require('../core/Maybe') | ||
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| const isArray = require('../core/isArray') | ||
| const isFunction = require('../core/isFunction') | ||
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| const identity = x => x | ||
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| const maybeToArray = require('./maybeToArray') | ||
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| test('maybeToArray transform', t => { | ||
| const f = bindFunc(maybeToArray) | ||
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| t.ok(isFunction(maybeToArray), 'is a function') | ||
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| const err = /maybeToArray: Argument must be a Maybe instanstace or a Maybe returning function/ | ||
| t.throws(f(undefined), err, 'throws if second arg is undefined') | ||
| t.throws(f(null), err, 'throws if second arg is null') | ||
| t.throws(f(0), err, 'throws if second arg is a falsey number') | ||
| t.throws(f(1), err, 'throws if second arg is a truthy number') | ||
| t.throws(f(''), err, 'throws if second arg is a falsey string') | ||
| t.throws(f('string'), err, 'throws if second arg is a truthy string') | ||
| t.throws(f(false), err, 'throws if second arg is false') | ||
| t.throws(f(true), err, 'throws if second arg is true') | ||
| t.throws(f([]), err, 'throws if second arg is an array') | ||
| t.throws(f({}), err, 'throws if second arg is an object') | ||
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| t.end() | ||
| }) | ||
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| test('maybeToArray with Maybe', t => { | ||
| const some = 'something' | ||
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| const good = maybeToArray(Maybe.Just(some)) | ||
| const bad = maybeToArray(Maybe.Nothing()) | ||
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| t.ok(isArray(good), 'returns an Array with a Just') | ||
| t.ok(isArray(bad), 'returns an Array with a Nothing') | ||
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| t.same(good, [ some ], 'Just maps to single item Array containing the value') | ||
| t.same(bad, [], 'Nothing maps to an empty Array') | ||
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| t.end() | ||
| }) | ||
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| test('maybeToArray with Maybe returning function', t => { | ||
| const some = 'something' | ||
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| t.ok(isFunction(maybeToArray(Maybe.of)), 'returns a function') | ||
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| const f = bindFunc(maybeToArray(identity)) | ||
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| const err = /maybeToArray: Argument must be a Maybe instanstace or a Maybe returning function/ | ||
| t.throws(f(undefined), err, 'throws if function returns undefined') | ||
| t.throws(f(null), err, 'throws if function returns null') | ||
| t.throws(f(0), err, 'throws if function returns a falsey number') | ||
| t.throws(f(1), err, 'throws if function returns a truthy number') | ||
| t.throws(f(''), err, 'throws if function returns a falsey string') | ||
| t.throws(f('string'), err, 'throws if function returns a truthy string') | ||
| t.throws(f(false), err, 'throws if function returns false') | ||
| t.throws(f(true), err, 'throws if function returns true') | ||
| t.throws(f([]), err, 'throws if function returns an array') | ||
| t.throws(f({}), err, 'throws if function returns an object') | ||
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| const lift = | ||
| x => x !== undefined ? Maybe.Just(x) : Maybe.Nothing() | ||
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| const good = maybeToArray(lift, some) | ||
| const bad = maybeToArray(lift, undefined) | ||
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| t.ok(isArray(good), 'returns an Array with a Just') | ||
| t.ok(isArray(bad), 'returns an Array with a Nothing') | ||
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| t.same(good, [ some ], 'Just maps to single item Array containing the value') | ||
| t.same(bad, [], 'Nothing maps to an empty Array') | ||
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| t.end() | ||
| }) |
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