# sanctuary-pair > Fantasy Land -compliant Pair type Latest version **2.1.0** (published 2020-01-19) · MIT license · 0 weekly downloads ## Install ```sh npm install sanctuary-pair pnpm add sanctuary-pair yarn add sanctuary-pair bun add sanctuary-pair ``` ## Health **Score 15/100 (F)** — status: abandoned. Positive: no vulnerabilities. Warnings: low downloads; no types; no esm support. Negative: abandoned; low maintenance score. ## Facts | | | |---|---| | Version | 2.1.0 | | Published | 2020-01-19 | | First published | 2018-05-28 | | Weekly downloads | 0 | | License | MIT | | TypeScript types | none | | Module format | CommonJS | | Dependencies | 2 | | Unpacked size | 22.5 KB | | Known vulnerabilities | 0 | | Install scripts | no | | GitHub stars | 11 | | Maintainers | davidchambers | ## Links - npm: https://www.npmjs.com/package/sanctuary-pair - Repository: https://github.com/sanctuary-js/sanctuary-pair - Homepage: https://github.com/sanctuary-js/sanctuary-pair#readme - Issues: https://github.com/sanctuary-js/sanctuary-pair/issues - npm.io page: https://npm.io/package/sanctuary-pair ## Dependencies (2) - [sanctuary-show](https://npm.io/package/sanctuary-show.md) 2.0.0 - [sanctuary-type-classes](https://npm.io/package/sanctuary-type-classes.md) 12.1.0 ## Recent versions - 2.1.0 (latest) — 2020-01-19 - 2.0.0 — 2019-11-03 - 1.2.0 — 2019-04-27 - 1.1.0 — 2019-02-21 - 1.0.0 — 2018-05-28 ## README Fantasy Land # sanctuary-pair Pair is the canonical product type: a value of type `Pair a b` always contains exactly two values: one of type `a`; one of type `b`. `Pair a b` satisfies the following [Fantasy Land][] specifications: ```javascript > const Useless = require ('sanctuary-useless') > const isTypeClass = x => . type (x) === 'sanctuary-type-classes/TypeClass@1' > S.map (k => k + ' '.repeat (16 - k.length) + . (Z[k].test (Pair (Useless) (Useless)) ? '\u2705 ' : . Z[k].test (Pair (['foo']) (['bar'])) ? '\u2705 * ' : . /* otherwise */ '\u274C ')) . (S.keys (S.unchecked.filter (isTypeClass) (Z))) [ 'Setoid ✅ * ', // if ‘a’ and ‘b’ satisfy Setoid . 'Ord ✅ * ', // if ‘a’ and ‘b’ satisfy Ord . 'Semigroupoid ✅ ', . 'Category ❌ ', . 'Semigroup ✅ * ', // if ‘a’ and ‘b’ satisfy Semigroup . 'Monoid ❌ ', . 'Group ❌ ', . 'Filterable ❌ ', . 'Functor ✅ ', . 'Bifunctor ✅ ', . 'Profunctor ❌ ', . 'Apply ✅ * ', // if ‘a’ satisfies Semigroup . 'Applicative ❌ ', . 'Chain ✅ * ', // if ‘a’ satisfies Semigroup . 'ChainRec ❌ ', . 'Monad ❌ ', . 'Alt ❌ ', . 'Plus ❌ ', . 'Alternative ❌ ', . 'Foldable ✅ ', . 'Traversable ✅ ', . 'Extend ✅ ', . 'Comonad ✅ ', . 'Contravariant ❌ ' ] ``` #### `Pair :: a -⁠> b -⁠> Pair a b` Pair's sole data constructor. Additionally, it serves as the Pair [type representative][]. ```javascript > Pair (1) (2) Pair (1) (2) ``` #### `Pair.fst :: Pair a b -⁠> a` `fst (Pair (x) (y))` is equivalent to `x`. ```javascript > Pair.fst (Pair ('abc') ([1, 2, 3])) 'abc' ``` #### `Pair.snd :: Pair a b -⁠> b` `snd (Pair (x) (y))` is equivalent to `y`. ```javascript > Pair.snd (Pair ('abc') ([1, 2, 3])) [1, 2, 3] ``` #### `Pair.swap :: Pair a b -⁠> Pair b a` `swap (Pair (x) (y))` is equivalent to `Pair (y) (x)`. ```javascript > Pair.swap (Pair ('abc') ([1, 2, 3])) Pair ([1, 2, 3]) ('abc') ``` #### `Pair#@@show :: (Showable a, Showable b) => Pair a b ~> () -⁠> String` `show (Pair (x) (y))` is equivalent to `'Pair (' + show (x) + ') (' + show (y) + ')'`. ```javascript > show (Pair ('abc') ([1, 2, 3])) 'Pair ("abc") ([1, 2, 3])' ``` #### `Pair#fantasy-land/equals :: (Setoid a, Setoid b) => Pair a b ~> Pair a b -⁠> Boolean` `Pair (x) (y)` is equal to `Pair (v) (w)` [iff][] `x` is equal to `v` and `y` is equal to `w` according to [`Z.equals`][]. ```javascript > S.equals (Pair ('abc') ([1, 2, 3])) (Pair ('abc') ([1, 2, 3])) true > S.equals (Pair ('abc') ([1, 2, 3])) (Pair ('abc') ([3, 2, 1])) false ``` #### `Pair#fantasy-land/lte :: (Ord a, Ord b) => Pair a b ~> Pair a b -⁠> Boolean` `Pair (x) (y)` is less than or equal to `Pair (v) (w)` [iff][] `x` is less than `v` or `x` is equal to `v` and `y` is less than or equal to `w` according to [`Z.lte`][]. ```javascript > S.filter (S.lte (Pair ('b') (2))) . ([Pair ('a') (1), Pair ('a') (2), Pair ('a') (3), . Pair ('b') (1), Pair ('b') (2), Pair ('b') (3), . Pair ('c') (1), Pair ('c') (2), Pair ('c') (3)]) [ Pair ('a') (1), . Pair ('a') (2), . Pair ('a') (3), . Pair ('b') (1), . Pair ('b') (2) ] ``` #### `Pair#fantasy-land/compose :: Pair a b ~> Pair b c -⁠> Pair a c` `compose (Pair (x) (y)) (Pair (v) (w))` is equivalent to `Pair (v) (y)`. ```javascript > S.compose (Pair ('a') (0)) (Pair ([1, 2, 3]) ('b')) Pair ([1, 2, 3]) (0) ``` #### `Pair#fantasy-land/concat :: (Semigroup a, Semigroup b) => Pair a b ~> Pair a b -⁠> Pair a b` `concat (Pair (x) (y)) (Pair (v) (w))` is equivalent to `Pair (concat (x) (v)) (concat (y) (w))`. ```javascript > S.concat (Pair ('abc') ([1, 2, 3])) (Pair ('xyz') ([4, 5, 6])) Pair ('abcxyz') ([1, 2, 3, 4, 5, 6]) ``` #### `Pair#fantasy-land/map :: Pair a b ~> (b -⁠> c) -⁠> Pair a c` `map (f) (Pair (x) (y))` is equivalent to `Pair (x) (f (y))`. ```javascript > S.map (Math.sqrt) (Pair ('abc') (256)) Pair ('abc') (16) ``` #### `Pair#fantasy-land/bimap :: Pair a c ~> (a -⁠> b, c -⁠> d) -⁠> Pair b d` `bimap (f) (g) (Pair (x) (y))` is equivalent to `Pair (f (x)) (g (y))`. ```javascript > S.bimap (S.toUpper) (Math.sqrt) (Pair ('abc') (256)) Pair ('ABC') (16) ``` #### `Pair#fantasy-land/ap :: Semigroup a => Pair a b ~> Pair a (b -⁠> c) -⁠> Pair a c` `ap (Pair (v) (f)) (Pair (x) (y))` is equivalent to `Pair (concat (v) (x)) (f (y))`. ```javascript > S.ap (Pair ('abc') (Math.sqrt)) (Pair ('xyz') (256)) Pair ('abcxyz') (16) ``` #### `Pair#fantasy-land/chain :: Semigroup a => Pair a b ~> (b -⁠> Pair a c) -⁠> Pair a c` `chain (f) (Pair (x) (y))` is equivalent to `Pair (concat (x) (fst (f (y)))) (snd (f (y)))`. ```javascript > S.chain (n => Pair (show (n)) (Math.sqrt (n))) (Pair ('abc') (256)) Pair ('abc256') (16) ``` #### `Pair#fantasy-land/reduce :: Pair a b ~> ((c, b) -⁠> c, c) -⁠> c` `reduce (f) (x) (Pair (v) (w))` is equivalent to `f (x) (w)`. ```javascript > S.reduce (S.concat) ([1, 2, 3]) (Pair ('abc') ([4, 5, 6])) [1, 2, 3, 4, 5, 6] ``` #### `Pair#fantasy-land/traverse :: Applicative f => Pair a b ~> (TypeRep f, b -⁠> f c) -⁠> f (Pair a c)` `traverse (_) (f) (Pair (x) (y))` is equivalent to `map (Pair (x)) (f (y))`. ```javascript > S.traverse (Array) (S.words) (Pair (123) ('foo bar baz')) [Pair (123) ('foo'), Pair (123) ('bar'), Pair (123) ('baz')] ``` #### `Pair#fantasy-land/extend :: Pair a b ~> (Pair a b -⁠> c) -⁠> Pair a c` `extend (f) (Pair (x) (y))` is equivalent to `Pair (x) (f (Pair (x) (y)))`. ```javascript > S.extend (S.reduce (S.add) (1)) (Pair ('abc') (99)) Pair ('abc') (100) ``` #### `Pair#fantasy-land/extract :: Pair a b ~> () -⁠> b` `extract (Pair (x) (y))` is equivalent to `y`. ```javascript > S.extract (Pair ('abc') ([1, 2, 3])) [1, 2, 3] ``` [Fantasy Land]: https://github.com/fantasyland/fantasy-land/tree/v4.0.1 [`Z.equals`]: https://github.com/sanctuary-js/sanctuary-type-classes/tree/v12.1.0#equals [`Z.lte`]: https://github.com/sanctuary-js/sanctuary-type-classes/tree/v12.1.0#lte [iff]: https://en.wikipedia.org/wiki/If_and_only_if [type representative]: https://github.com/fantasyland/fantasy-land/tree/v4.0.1#type-representatives --- _Source: https://npm.io/package/sanctuary-pair · Machine-readable twin of the npm.io package page. 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