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<a href="https://github.com/fantasyland/fantasy-land"><img alt="Fantasy Land" src="https://raw.githubusercontent.com/fantasyland/fantasy-land/master/logo.png" width="75" height="75" align="left"></a>
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:
> 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 ❌ ' ]
<a name="Identity" href="https://github.com/sanctuary-js/sanctuary-identity/blob/v2.1.0/index.js#L121">Identity :: a -> Identity a</a>
Identity's sole data constructor. Additionally, it serves as the Identity type representative.
> Identity (42)
Identity (42)
<a name="Identity.fantasy-land/of" href="https://github.com/sanctuary-js/sanctuary-identity/blob/v2.1.0/index.js#L145">Identity.fantasy-land/of :: a -> Identity a</a>
of (Identity) (x) is equivalent to Identity (x).
> S.of (Identity) (42)
Identity (42)
<a name="Identity.fantasy-land/chainRec" href="https://github.com/sanctuary-js/sanctuary-identity/blob/v2.1.0/index.js#L158">Identity.fantasy-land/chainRec :: ((a -> c, b -> c, a) -> Identity c, a) -> Identity b</a>
> 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)
<a name="Identity.prototype.@@show" href="https://github.com/sanctuary-js/sanctuary-identity/blob/v2.1.0/index.js#L181">Identity#@@show :: Showable a => Identity a ~> () -> String</a>
show (Identity (x)) is equivalent to 'Identity (' + show (x) + ')'.
> show (Identity (['foo', 'bar', 'baz']))
'Identity (["foo", "bar", "baz"])'
<a name="Identity.prototype.fantasy-land/equals" href="https://github.com/sanctuary-js/sanctuary-identity/blob/v2.1.0/index.js#L193">Identity#fantasy-land/equals :: Setoid a => Identity a ~> Identity a -> Boolean</a>
Identity (x) is equal to Identity (y) iff x is equal to y
according to Z.equals.
> S.equals (Identity ([1, 2, 3])) (Identity ([1, 2, 3]))
true
> S.equals (Identity ([1, 2, 3])) (Identity ([3, 2, 1]))
false
<a name="Identity.prototype.fantasy-land/lte" href="https://github.com/sanctuary-js/sanctuary-identity/blob/v2.1.0/index.js#L209">Identity#fantasy-land/lte :: Ord a => Identity a ~> Identity a -> Boolean</a>
Identity (x) is less than or equal to Identity (y) iff x is
less than or equal to y according to Z.lte.
> S.filter (S.lte (Identity (1)))
. ([Identity (0), Identity (1), Identity (2)])
[Identity (0), Identity (1)]
<a name="Identity.prototype.fantasy-land/concat" href="https://github.com/sanctuary-js/sanctuary-identity/blob/v2.1.0/index.js#L223">Identity#fantasy-land/concat :: Semigroup a => Identity a ~> Identity a -> Identity a</a>
concat (Identity (x)) (Identity (y)) is equivalent to
Identity (concat (x) (y)).
> S.concat (Identity ([1, 2, 3])) (Identity ([4, 5, 6]))
Identity ([1, 2, 3, 4, 5, 6])
<a name="Identity.prototype.fantasy-land/map" href="https://github.com/sanctuary-js/sanctuary-identity/blob/v2.1.0/index.js#L236">Identity#fantasy-land/map :: Identity a ~> (a -> b) -> Identity b</a>
map (f) (Identity (x)) is equivalent to Identity (f (x)).
> S.map (Math.sqrt) (Identity (64))
Identity (8)
<a name="Identity.prototype.fantasy-land/ap" href="https://github.com/sanctuary-js/sanctuary-identity/blob/v2.1.0/index.js#L248">Identity#fantasy-land/ap :: Identity a ~> Identity (a -> b) -> Identity b</a>
ap (Identity (f)) (Identity (x)) is equivalent to Identity (f (x)).
> S.ap (Identity (Math.sqrt)) (Identity (64))
Identity (8)
<a name="Identity.prototype.fantasy-land/chain" href="https://github.com/sanctuary-js/sanctuary-identity/blob/v2.1.0/index.js#L260">Identity#fantasy-land/chain :: Identity a ~> (a -> Identity b) -> Identity b</a>
chain (f) (Identity (x)) is equivalent to f (x).
> S.chain (n => Identity (n + 1)) (Identity (99))
Identity (100)
<a name="Identity.prototype.fantasy-land/reduce" href="https://github.com/sanctuary-js/sanctuary-identity/blob/v2.1.0/index.js#L272">Identity#fantasy-land/reduce :: Identity a ~> ((b, a) -> b, b) -> b</a>
reduce (f) (x) (Identity (y)) is equivalent to f (x) (y).
> S.reduce (S.concat) ([1, 2, 3]) (Identity ([4, 5, 6]))
[1, 2, 3, 4, 5, 6]
<a name="Identity.prototype.fantasy-land/traverse" href="https://github.com/sanctuary-js/sanctuary-identity/blob/v2.1.0/index.js#L284">Identity#fantasy-land/traverse :: Applicative f => Identity a ~> (TypeRep f, a -> f b) -> f (Identity b)</a>
traverse (_) (f) (Identity (x)) is equivalent to
map (Identity) (f (x)).
> S.traverse (Array) (x => [x + 1, x + 2, x + 3]) (Identity (100))
[Identity (101), Identity (102), Identity (103)]
<a name="Identity.prototype.fantasy-land/extend" href="https://github.com/sanctuary-js/sanctuary-identity/blob/v2.1.0/index.js#L297">Identity#fantasy-land/extend :: Identity a ~> (Identity a -> b) -> Identity b</a>
extend (f) (Identity (x)) is equivalent to
Identity (f (Identity (x))).
> S.extend (S.reduce (S.add) (1)) (Identity (99))
Identity (100)
<a name="Identity.prototype.fantasy-land/extract" href="https://github.com/sanctuary-js/sanctuary-identity/blob/v2.1.0/index.js#L310">Identity#fantasy-land/extract :: Identity a ~> () -> a</a>
extract (Identity (x)) is equivalent to x.
> S.extract (Identity (42))
42