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https://github.com/sanctuary-js/sanctuary-identity
:rainbow: Fantasy Land -compliant Identity type
https://github.com/sanctuary-js/sanctuary-identity
fantasy-land sanctuary
Last synced: 15 days ago
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:rainbow: Fantasy Land -compliant Identity type
- Host: GitHub
- URL: https://github.com/sanctuary-js/sanctuary-identity
- Owner: sanctuary-js
- License: mit
- Created: 2017-03-19T14:05:59.000Z (almost 8 years ago)
- Default Branch: main
- Last Pushed: 2024-10-27T10:30:24.000Z (2 months ago)
- Last Synced: 2024-12-10T14:32:34.418Z (23 days ago)
- Topics: fantasy-land, sanctuary
- Language: JavaScript
- Size: 112 KB
- Stars: 27
- Watchers: 11
- Forks: 5
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Contributing: .github/CONTRIBUTING.md
- Funding: .github/FUNDING.yml
- License: LICENSE
Awesome Lists containing this project
README
# sanctuary-identity
Identity is the simplest container type: a value of type `Identity a`
always contains exactly one value, of type `a`.
`Identity a` 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 (Identity (Useless)) ? '\u2705 ' :
. Z[k].test (Identity (['foo'])) ? '\u2705 * ' :
. /* otherwise */ '\u274C '))
. (S.keys (S.unchecked.filter (isTypeClass) (Z)))
[ 'Setoid ✅ * ', // if ‘a’ satisfies Setoid
. 'Ord ✅ * ', // if ‘a’ satisfies Ord
. 'Semigroupoid ❌ ',
. 'Category ❌ ',
. 'Semigroup ✅ * ', // if ‘a’ satisfies Semigroup
. 'Monoid ❌ ',
. 'Group ❌ ',
. 'Filterable ❌ ',
. 'Functor ✅ ',
. 'Bifunctor ❌ ',
. 'Profunctor ❌ ',
. 'Apply ✅ ',
. 'Applicative ✅ ',
. 'Chain ✅ ',
. 'ChainRec ✅ ',
. 'Monad ✅ ',
. 'Alt ❌ ',
. 'Plus ❌ ',
. 'Alternative ❌ ',
. 'Foldable ✅ ',
. 'Traversable ✅ ',
. 'Extend ✅ ',
. 'Comonad ✅ ',
. 'Contravariant ❌ ' ]
```
#### `Identity :: a -> Identity a`
Identity's sole data constructor. Additionally, it serves as the
Identity [type representative][].
```javascript
> Identity (42)
Identity (42)
```
#### `Identity.fantasy-land/of :: a -> Identity a`
`of (Identity) (x)` is equivalent to `Identity (x)`.
```javascript
> S.of (Identity) (42)
Identity (42)
```
#### `Identity.fantasy-land/chainRec :: ((a -> c, b -> c, a) -> Identity c, a) -> Identity b`
```javascript
> Z.chainRec (
. Identity,
. (next, done, x) => Identity (x >= 0 ? done (x * x) : next (x + 1)),
. 8
. )
Identity (64)
> Z.chainRec (
. Identity,
. (next, done, x) => Identity (x >= 0 ? done (x * x) : next (x + 1)),
. -8
. )
Identity (0)
```
#### `Identity#@@show :: Showable a => Identity a ~> () -> String`
`show (Identity (x))` is equivalent to `'Identity (' + show (x) + ')'`.
```javascript
> show (Identity (['foo', 'bar', 'baz']))
'Identity (["foo", "bar", "baz"])'
```
#### `Identity#fantasy-land/equals :: Setoid a => Identity a ~> Identity a -> Boolean`
`Identity (x)` is equal to `Identity (y)` [iff][] `x` is equal to `y`
according to [`Z.equals`][].
```javascript
> S.equals (Identity ([1, 2, 3])) (Identity ([1, 2, 3]))
true
> S.equals (Identity ([1, 2, 3])) (Identity ([3, 2, 1]))
false
```
#### `Identity#fantasy-land/lte :: Ord a => Identity a ~> Identity a -> Boolean`
`Identity (x)` is less than or equal to `Identity (y)` [iff][] `x` is
less than or equal to `y` according to [`Z.lte`][].
```javascript
> S.filter (S.lte (Identity (1)))
. ([Identity (0), Identity (1), Identity (2)])
[Identity (0), Identity (1)]
```
#### `Identity#fantasy-land/concat :: Semigroup a => Identity a ~> Identity a -> Identity a`
`concat (Identity (x)) (Identity (y))` is equivalent to
`Identity (concat (x) (y))`.
```javascript
> S.concat (Identity ([1, 2, 3])) (Identity ([4, 5, 6]))
Identity ([1, 2, 3, 4, 5, 6])
```
#### `Identity#fantasy-land/map :: Identity a ~> (a -> b) -> Identity b`
`map (f) (Identity (x))` is equivalent to `Identity (f (x))`.
```javascript
> S.map (Math.sqrt) (Identity (64))
Identity (8)
```
#### `Identity#fantasy-land/ap :: Identity a ~> Identity (a -> b) -> Identity b`
`ap (Identity (f)) (Identity (x))` is equivalent to `Identity (f (x))`.
```javascript
> S.ap (Identity (Math.sqrt)) (Identity (64))
Identity (8)
```
#### `Identity#fantasy-land/chain :: Identity a ~> (a -> Identity b) -> Identity b`
`chain (f) (Identity (x))` is equivalent to `f (x)`.
```javascript
> S.chain (n => Identity (n + 1)) (Identity (99))
Identity (100)
```
#### `Identity#fantasy-land/reduce :: Identity a ~> ((b, a) -> b, b) -> b`
`reduce (f) (x) (Identity (y))` is equivalent to `f (x) (y)`.
```javascript
> S.reduce (S.concat) ([1, 2, 3]) (Identity ([4, 5, 6]))
[1, 2, 3, 4, 5, 6]
```
`traverse (_) (f) (Identity (x))` is equivalent to
`map (Identity) (f (x))`.
```javascript
> S.traverse (Array) (x => [x + 1, x + 2, x + 3]) (Identity (100))
[Identity (101), Identity (102), Identity (103)]
```
#### `Identity#fantasy-land/extend :: Identity a ~> (Identity a -> b) -> Identity b`
`extend (f) (Identity (x))` is equivalent to
`Identity (f (Identity (x)))`.
```javascript
> S.extend (S.reduce (S.add) (1)) (Identity (99))
Identity (100)
```
#### `Identity#fantasy-land/extract :: Identity a ~> () -> a`
`extract (Identity (x))` is equivalent to `x`.
```javascript
> S.extract (Identity (42))
42
```
[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