everything

.circleci/config.yml

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+version: 2.1
+
+orbs:
+  node: circleci/[email protected]
+
+workflows:
+  test:
+    jobs:
+      - node/test:
+          setup:
+            # derive cache key from package.json
+            - run: cp package.json package-lock.json
+          override-ci-command: rm package-lock.json && npm install && git checkout -- package.json
+          matrix:
+            parameters:
+              version:
+                - 18.0.0
+                - 20.0.0
+                - 22.0.0

.config

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+repo-owner = sanctuary-js
+repo-name = sanctuary-constant
+contributing-file = .github/CONTRIBUTING.md

.eslintrc.json

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+{
+  "root": true,
+  "extends": ["./node_modules/sanctuary-style/eslint.json"],
+  "parserOptions": {"ecmaVersion": 2020, "sourceType": "module"},
+  "globals": {"globalThis": "readonly"}
+}

.github/CONTRIBUTING.md

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+# Contributing
+
+Note: __README.md__ is generated from comments in __index.js__. Do not modify
+__README.md__ directly.
+
+1.  Update local main branch:
+
+        $ git checkout main
+        $ git pull upstream main
+
+2.  Create feature branch:
+
+        $ git checkout -b feature-x
+
+3.  Make one or more atomic commits, and ensure that each commit has a
+    descriptive commit message. Commit messages should be line wrapped
+    at 72 characters.
+
+4.  Run `npm test`, and address any errors. Preferably, fix commits in place
+    using `git rebase` or `git commit --amend` to make the changes easier to
+    review.
+
+5.  Push:
+
+        $ git push origin feature-x
+
+6.  Open a pull request.

.github/FUNDING.yml

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+github: [davidchambers]

.gitignore

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+/coverage/
+/node_modules/

.npmrc

@@ -0,0 +1 @@
+package-lock=false

LICENSE

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+The MIT License (MIT)
+
+Copyright (c) 2019 Sanctuary
+
+Permission is hereby granted, free of charge, to any person
+obtaining a copy of this software and associated documentation
+files (the "Software"), to deal in the Software without
+restriction, including without limitation the rights to use,
+copy, modify, merge, publish, distribute, sublicense, and/or
+sell copies of the Software, and to permit persons to whom the
+Software is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.

index.js

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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-constant
+//.
+//. A value of type `Constant a b` always contains exactly one value,
+//. of type `a`. Mapping over a `Constant a b` has no effect because
+//. the `b -> c` function is never applied.
+
+import show from 'sanctuary-show';
+import Z from 'sanctuary-type-classes';
+
+export {Constant};
+
+const constantTypeIdent = 'sanctuary-constant/Constant@1';
+
+//. ```javascript
+//. > import S from 'sanctuary'
+//. > import $ from 'sanctuary-def'
+//. > import Useless from 'sanctuary-useless'
+//. ```
+//.
+//. `Constant a b` satisfies the following [Fantasy Land][] specifications:
+//.
+//. ```javascript
+//. > S.map (k =>
+//. .   k + ' '.repeat (16 - k.length) +
+//. .   (Z[k].test (Constant (Useless.constructor) (Useless)) ? '\u2705   ' :
+//. .    Z[k].test (Constant (Array) (['foo', 'bar', 'baz'])) ? '\u2705 * ' :
+//. .    /* otherwise */                                        '\u274C   ')
+//. . ) (S.keys (S.unchecked.filter (S.is ($.TypeClass)) (Z)))
+//. [ 'Setoid          ✅ * ',  // if ‘a’ satisfies Setoid
+//. . 'Ord             ✅ * ',  // if ‘a’ satisfies Ord
+//. . 'Semigroupoid    ❌   ',
+//. . 'Category        ❌   ',
+//. . 'Semigroup       ✅ * ',  // if ‘a’ satisfies Semigroup
+//. . 'Monoid          ❌   ',
+//. . 'Group           ❌   ',
+//. . 'Filterable      ❌   ',
+//. . 'Functor         ✅   ',
+//. . 'Bifunctor       ✅   ',
+//. . 'Profunctor      ❌   ',
+//. . 'Apply           ✅ * ',  // if ‘a’ satisfies Semigroup
+//. . 'Applicative     ✅ * ',  // if ‘a’ satisfies Monoid
+//. . 'Chain           ❌   ',
+//. . 'ChainRec        ❌   ',
+//. . 'Monad           ❌   ',
+//. . 'Alt             ❌   ',
+//. . 'Plus            ❌   ',
+//. . 'Alternative     ❌   ',
+//. . 'Foldable        ✅   ',
+//. . 'Traversable     ✅   ',
+//. . 'Extend          ❌   ',
+//. . 'Comonad         ❌   ',
+//. . 'Contravariant   ❌   ' ]
+//. ```
+
+//# Constant :: TypeRep a -> a -> Constant a b
+//.
+//. Constant's sole data constructor. The [type representative][] makes
+//. `Constant (M)` an [Applicative][]-compatible type representative if
+//. `M` represents some monoidal type.
+//.
+//. ```javascript
+//. > Constant (String) ('abc')
+//. Constant (String) ('abc')
+//.
+//. > Constant (Number) (123)
+//. Constant (Number) (123)
+//. ```
+const Constant = A => {
+  const prototype = {
+    /* eslint-disable key-spacing */
+    'constructor':            Constant$bound,
+    '@@type':                 constantTypeIdent,
+    '@@show':                 Constant$prototype$show,
+    'fantasy-land/map':       Constant$prototype$map,
+    'fantasy-land/bimap':     Constant$prototype$bimap,
+    'fantasy-land/reduce':    Constant$prototype$reduce,
+    'fantasy-land/traverse':  Constant$prototype$traverse,
+    /* eslint-enable key-spacing */
+  };
+
+  if (globalThis.process?.versions?.node != null) {
+    const inspect = Symbol.for ('nodejs.util.inspect.custom');
+    prototype[inspect] = Constant$prototype$show;
+  }
+
+  /* c8 ignore start */
+  if (typeof globalThis.Deno?.customInspect === 'symbol') {
+    const inspect = globalThis.Deno.customInspect;
+    prototype[inspect] = Constant$prototype$show;
+  }
+  /* c8 ignore stop */
+
+  function Constant$bound(value) {
+    const constant = Object.create (prototype);
+    if (Z.Setoid.test (value)) {
+      constant['fantasy-land/equals'] = Constant$prototype$equals;
+      if (Z.Ord.test (value)) {
+        constant['fantasy-land/lte'] = Constant$prototype$lte;
+      }
+    }
+    if (Z.Semigroup.test (value)) {
+      constant['fantasy-land/concat'] = Constant$prototype$concat;
+      constant['fantasy-land/ap'] = Constant$prototype$ap;
+    }
+    constant.value = value;
+    return constant;
+  }
+
+  //  XXX: sanctuary-show@3 only respects @@show on "objects". Fool it.
+  Constant$bound[Symbol.toStringTag] = 'Object';
+
+  Constant$bound['@@show'] = () => {
+    if (!(Object.prototype.hasOwnProperty.call (A, 'name'))) {
+      const source = String (A);
+      const match = /^\s*function ([$_A-Za-z][$_A-Za-z0-9]*)/.exec (source);
+      return 'Constant (' + (match == null ? source : match[1]) + ')';
+    } else if (A.name === Constant$bound.name) {
+      return 'Constant (' + show (A) + ')';
+    } else {
+      return 'Constant (' + A.name + ')';
+    }
+  };
+
+  //# Constant.fantasy-land/of :: Monoid m => a -> Constant m a
+  //.
+  //. `of (Constant (M)) (x)` is equivalent to `Constant (M) (empty (M))`.
+  //.
+  //. ```javascript
+  //. > S.of (Constant (Array)) (42)
+  //. Constant (Array) ([])
+  //.
+  //. > S.of (Constant (String)) (42)
+  //. Constant (String) ('')
+  //. ```
+  (() => {
+    let empty;
+    try { empty = Z.empty (A); } catch (err) { return; }
+    Constant$bound['fantasy-land/of'] = x => Constant$bound (empty);
+  }) ();
+
+  //# Constant#@@show :: Showable a => Constant a b ~> () -> String
+  //.
+  //. `show (Constant (A) (x))` is equivalent to
+  //. `'Constant (' + A.name + ') (' + show (x) + ')'`.
+  //.
+  //. ```javascript
+  //. > S.show (Constant (Array) (['foo', 'bar', 'baz']))
+  //. 'Constant (Array) (["foo", "bar", "baz"])'
+  //. ```
+  function Constant$prototype$show() {
+    return show (Constant$bound) + ' (' + show (this.value) + ')';
+  }
+
+  //# Constant#fantasy-land/equals :: Setoid a => Constant a b ~> Constant a b -> Boolean
+  //.
+  //. `Constant (A) (x)` is equal to `Constant (A) (y)` [iff][] `x` is
+  //. equal to `y` according to [`Z.equals`][].
+  //.
+  //. ```javascript
+  //. > S.equals (Constant (Array) ([1, 2, 3]))
+  //. .          (Constant (Array) ([1, 2, 3]))
+  //. true
+  //.
+  //. > S.equals (Constant (Array) ([1, 2, 3]))
+  //. .          (Constant (Array) ([3, 2, 1]))
+  //. false
+  //. ```
+  function Constant$prototype$equals(other) {
+    return Z.equals (this.value, other.value);
+  }
+
+  //# Constant#fantasy-land/lte :: Ord a => Constant a b ~> Constant a b -> Boolean
+  //.
+  //. `Constant (A) (x)` is less than or equal to `Constant (A) (y)` [iff][]
+  //. `x` is less than or equal to `y` according to [`Z.lte`][].
+  //.
+  //. ```javascript
+  //. > S.filter (S.lte (Constant (Number) (1)))
+  //. .          ([Constant (Number) (0),
+  //. .            Constant (Number) (1),
+  //. .            Constant (Number) (2)])
+  //. [Constant (Number) (0), Constant (Number) (1)]
+  //. ```
+  function Constant$prototype$lte(other) {
+    return Z.lte (this.value, other.value);
+  }
+
+  //# Constant#fantasy-land/concat :: Semigroup a => Constant a b ~> Constant a b -> Constant a b
+  //.
+  //. `concat (Constant (A) (x)) (Constant (A) (y))` is equivalent to
+  //. `Constant (A) (concat (x) (y))`.
+  //.
+  //. ```javascript
+  //. > S.concat (Constant (Array) ([1, 2, 3]))
+  //. .          (Constant (Array) ([4, 5, 6]))
+  //. Constant (Array) ([1, 2, 3, 4, 5, 6])
+  //. ```
+  function Constant$prototype$concat(other) {
+    return Constant$bound (Z.concat (this.value, other.value));
+  }
+
+  //# Constant#fantasy-land/map :: Constant a b ~> (b -> c) -> Constant a c
+  //.
+  //. `map (f) (Constant (A) (x))` is equivalent to `Constant (A) (x)`.
+  //.
+  //. ```javascript
+  //. > S.map (Math.sqrt) (Constant (Number) (64))
+  //. Constant (Number) (64)
+  //. ```
+  function Constant$prototype$map(f) {
+    return this;
+  }
+
+  //# Constant#fantasy-land/bimap :: Constant a c ~> (a -> b, c -> d) -> Constant b d
+  //.
+  //. `bimap (f) (g) (Constant (A) (x))` is equivalent to
+  //. `Constant (A) (f (x))`.
+  //.
+  //. ```javascript
+  //. > S.bimap (s => s.length) (Math.sqrt) (Constant (String) ('abc'))
+  //. Constant (Number) (3)
+  //. ```
+  function Constant$prototype$bimap(f, g) {
+    const x = f (this.value);
+    return Constant (x.constructor) (x);
+  }
+
+  //# Constant#fantasy-land/ap :: Semigroup a => Constant a b ~> Constant a (b -> c) -> Constant a c
+  //.
+  //. `ap (Constant (A) (x)) (Constant (A) (y))` is equivalent to
+  //. `concat (Constant (A) (x)) (Constant (A) (y))`.
+  //.
+  //. ```javascript
+  //. > S.ap (Constant (Array) ([1, 2, 3])) (Constant (Array) ([4, 5, 6]))
+  //. Constant (Array) ([1, 2, 3, 4, 5, 6])
+  //. ```
+  function Constant$prototype$ap(other) {
+    return Z.concat (other, this);
+  }
+
+  //# Constant#fantasy-land/reduce :: Constant a b ~> ((c, b) -> c, c) -> c
+  //.
+  //. `reduce (f) (x) (Constant (A) (y))` is equivalent to `x`.
+  //.
+  //. ```javascript
+  //. > S.reduce (S.add) (100) (Constant (Number) (42))
+  //. 100
+  //. ```
+  function Constant$prototype$reduce(f, x) {
+    return x;
+  }
+
+  //# Constant#fantasy-land/traverse :: Applicative f => Constant a b ~> (TypeRep f, b -> f c) -> f (Constant a c)
+  //.
+  //. `traverse (A) (f) (Constant (X) (x))` is equivalent to
+  //. `of (A) (Constant (X) (x))`.
+  //.
+  //. ```javascript
+  //. > S.traverse (Array) (Math.sqrt) (Constant (Number) (64))
+  //. [Constant (Number) (64)]
+  //. ```
+  function Constant$prototype$traverse(typeRep, f) {
+    return Z.of (typeRep, this);
+  }
+
+  return Constant$bound;
+};
+
+//. [Applicative]:              v:fantasyland/fantasy-land#Applicative
+//. [Fantasy Land]:             v:fantasyland/fantasy-land
+//. [`Z.equals`]:               v:sanctuary-js/sanctuary-type-classes#equals
+//. [`Z.lte`]:                  v:sanctuary-js/sanctuary-type-classes#lte
+//. [iff]:                      https://en.wikipedia.org/wiki/If_and_only_if
+//. [type representative]:      v:fantasyland/fantasy-land#type-representatives