| 1 | /*!
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| 2 | * Copyright (c) 2017-2018 by The Funfix Project Developers.
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| 3 | * Some rights reserved.
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| 4 | *
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| 5 | * Licensed under the Apache License, Version 2.0 (the "License");
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| 6 | * you may not use this file except in compliance with the License.
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| 7 | * You may obtain a copy of the License at
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| 8 | *
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| 9 | * http://www.apache.org/licenses/LICENSE-2.0
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| 10 | *
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| 11 | * Unless required by applicable law or agreed to in writing, software
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| 12 | * distributed under the License is distributed on an "AS IS" BASIS,
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| 13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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| 14 | * See the License for the specific language governing permissions and
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| 15 | * limitations under the License.
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| 16 | */
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| 17 |
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| 18 | import { Constructor, Setoid, Monad } from "funland"
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| 19 |
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| 20 | /**
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| 21 | * Given a function, converts it into a method where `this` gets
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| 22 | * passed around as the last argument.
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| 23 | */
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| 24 | export function convertToMethod(f: Function): Function {
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| 25 | return function (this: any) {
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| 26 | const args = Array.prototype.slice.call(arguments)
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| 27 | args.push(this)
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| 28 | return f.apply(undefined, args)
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| 29 | }
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| 30 | }
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| 31 |
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| 32 | /**
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| 33 | * Given a constructor, searches for all Fantasy-Land compatible
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| 34 | * methods registered on its `prototype` and also registers them
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| 35 | * using Fantasy-Land compatible symbols.
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| 36 | *
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| 37 | * For example:
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| 38 | *
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| 39 | * ```typescript
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| 40 | * class Box<A> {
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| 41 | * constructor(public readonly value: A) {}
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| 42 | *
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| 43 | * // Setoid
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| 44 | * equals(that: Box<A>) {
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| 45 | * return that && this.value === that.value
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| 46 | * }
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| 47 | * // Functor
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| 48 | * map<B>(f: (a: A) => B): Box<B> {
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| 49 | * return new Box(f(this.value))
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| 50 | * }
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| 51 | * }
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| 52 | *
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| 53 | * // Registering Fantasy-Land compatible symbols
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| 54 | * fantasyLandRegister(Box)
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| 55 | * ```
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| 56 | *
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| 57 | * The above registration call would make `fantasy-land/equals` and
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| 58 | * `fantasy-land/functor` available on `Box.prototype`.
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| 59 | *
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| 60 | * @private
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| 61 | * @Hidden
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| 62 | */
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| 63 | export function fantasyLandRegister<A>(
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| 64 | cls: Constructor<A>,
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| 65 | monad?: Monad<any>,
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| 66 | setoid?: Setoid<any>): void {
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| 67 |
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| 68 | const c = cls as any
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| 69 | const p = c.prototype
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| 70 |
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| 71 | const fl = "fantasy-land/"
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| 72 | const equals = "equals"
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| 73 | const flEquals = fl + equals
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| 74 | const map = "map"
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| 75 | const flMap = fl + map
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| 76 | const ap = "ap"
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| 77 | const flAp = fl + ap
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| 78 | const flOf = fl + "of"
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| 79 | const chain = "chain"
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| 80 | const flChain = fl + chain
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| 81 | const chainRec = "chainRec"
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| 82 | const flChainRec = fl + chainRec
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| 83 |
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| 84 | // Setoid
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| 85 | if (p[equals]) {
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| 86 | p[flEquals] = p[equals]
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| 87 | } else {
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| 88 | /* istanbul ignore else */
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| 89 | if (setoid) p[flEquals] = convertToMethod(setoid.equals)
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| 90 | }
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| 91 | // Functor
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| 92 | if (p[map]) {
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| 93 | p[flMap] = p[map]
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| 94 | } else {
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| 95 | /* istanbul ignore else */
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| 96 | if (monad) p[flMap] = convertToMethod(monad.map)
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| 97 | }
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| 98 | // Apply
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| 99 | if (p[ap]) {
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| 100 | p[flAp] = p[ap]
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| 101 | } else {
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| 102 | /* istanbul ignore else */
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| 103 | if (monad) p[flAp] = convertToMethod(monad.ap)
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| 104 | }
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| 105 | // Applicative
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| 106 | if (c["pure"]) {
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| 107 | c[flOf] = c["pure"]
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| 108 | } else {
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| 109 | /* istanbul ignore else */
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| 110 | if (monad) c[flOf] = monad.of
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| 111 | }
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| 112 | // Chain
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| 113 | if (p[chain]) {
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| 114 | p[flChain] = p[chain]
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| 115 | } else {
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| 116 | /* istanbul ignore else */
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| 117 | if (monad) p[flChain] = convertToMethod(monad.chain)
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| 118 | }
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| 119 | // ChainRec
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| 120 | if (c[chainRec]) {
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| 121 | c[flChainRec] = c[chainRec]
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| 122 | } else {
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| 123 | /* istanbul ignore else */
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| 124 | if (monad) c[flChainRec] = monad.chainRec
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| 125 | }
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| 126 | }
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