374 lines
9.1 KiB
JavaScript
374 lines
9.1 KiB
JavaScript
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/**
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* If a type `A` can form a `Semigroup` it has an **associative** binary operation.
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*
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* ```ts
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* interface Semigroup<A> {
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* readonly concat: (x: A, y: A) => A
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* }
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* ```
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*
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* Associativity means the following equality must hold for any choice of `x`, `y`, and `z`.
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*
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* ```ts
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* concat(x, concat(y, z)) = concat(concat(x, y), z)
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* ```
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*
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* A common example of a semigroup is the type `string` with the operation `+`.
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*
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* ```ts
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* import { Semigroup } from 'fp-ts/Semigroup'
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*
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* const semigroupString: Semigroup<string> = {
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* concat: (x, y) => x + y
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* }
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*
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* const x = 'x'
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* const y = 'y'
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* const z = 'z'
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*
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* semigroupString.concat(x, y) // 'xy'
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*
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* semigroupString.concat(x, semigroupString.concat(y, z)) // 'xyz'
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*
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* semigroupString.concat(semigroupString.concat(x, y), z) // 'xyz'
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* ```
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*
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* *Adapted from https://typelevel.org/cats*
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*
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* @since 2.0.0
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*/
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import { getSemigroup, identity } from './function';
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import * as _ from './internal';
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import * as M from './Magma';
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import * as Or from './Ord';
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// -------------------------------------------------------------------------------------
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// constructors
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// -------------------------------------------------------------------------------------
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/**
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* Get a semigroup where `concat` will return the minimum, based on the provided order.
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*
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* @example
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* import * as N from 'fp-ts/number'
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* import * as S from 'fp-ts/Semigroup'
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*
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* const S1 = S.min(N.Ord)
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*
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* assert.deepStrictEqual(S1.concat(1, 2), 1)
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*
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* @category constructors
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* @since 2.10.0
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*/
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export var min = function (O) { return ({
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concat: Or.min(O)
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}); };
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/**
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* Get a semigroup where `concat` will return the maximum, based on the provided order.
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*
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* @example
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* import * as N from 'fp-ts/number'
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* import * as S from 'fp-ts/Semigroup'
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*
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* const S1 = S.max(N.Ord)
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*
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* assert.deepStrictEqual(S1.concat(1, 2), 2)
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*
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* @category constructors
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* @since 2.10.0
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*/
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export var max = function (O) { return ({
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concat: Or.max(O)
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}); };
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/**
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* @category constructors
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* @since 2.10.0
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*/
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export var constant = function (a) { return ({
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concat: function () { return a; }
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}); };
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// -------------------------------------------------------------------------------------
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// combinators
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// -------------------------------------------------------------------------------------
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/**
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* The dual of a `Semigroup`, obtained by swapping the arguments of `concat`.
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*
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* @example
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* import { reverse } from 'fp-ts/Semigroup'
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* import * as S from 'fp-ts/string'
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*
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* assert.deepStrictEqual(reverse(S.Semigroup).concat('a', 'b'), 'ba')
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*
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* @since 2.10.0
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*/
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export var reverse = M.reverse;
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/**
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* Given a struct of semigroups returns a semigroup for the struct.
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*
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* @example
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* import { struct } from 'fp-ts/Semigroup'
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* import * as N from 'fp-ts/number'
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*
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* interface Point {
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* readonly x: number
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* readonly y: number
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* }
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*
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* const S = struct<Point>({
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* x: N.SemigroupSum,
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* y: N.SemigroupSum
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* })
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*
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* assert.deepStrictEqual(S.concat({ x: 1, y: 2 }, { x: 3, y: 4 }), { x: 4, y: 6 })
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*
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* @since 2.10.0
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*/
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export var struct = function (semigroups) { return ({
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concat: function (first, second) {
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var r = {};
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for (var k in semigroups) {
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if (_.has.call(semigroups, k)) {
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r[k] = semigroups[k].concat(first[k], second[k]);
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}
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}
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return r;
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}
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}); };
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/**
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* Given a tuple of semigroups returns a semigroup for the tuple.
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*
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* @example
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* import { tuple } from 'fp-ts/Semigroup'
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* import * as B from 'fp-ts/boolean'
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* import * as N from 'fp-ts/number'
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* import * as S from 'fp-ts/string'
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*
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* const S1 = tuple(S.Semigroup, N.SemigroupSum)
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* assert.deepStrictEqual(S1.concat(['a', 1], ['b', 2]), ['ab', 3])
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*
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* const S2 = tuple(S.Semigroup, N.SemigroupSum, B.SemigroupAll)
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* assert.deepStrictEqual(S2.concat(['a', 1, true], ['b', 2, false]), ['ab', 3, false])
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*
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* @since 2.10.0
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*/
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export var tuple = function () {
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var semigroups = [];
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for (var _i = 0; _i < arguments.length; _i++) {
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semigroups[_i] = arguments[_i];
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}
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return ({
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concat: function (first, second) { return semigroups.map(function (s, i) { return s.concat(first[i], second[i]); }); }
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});
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};
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/**
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* Between each pair of elements insert `middle`.
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*
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* @example
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* import { intercalate } from 'fp-ts/Semigroup'
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* import * as S from 'fp-ts/string'
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* import { pipe } from 'fp-ts/function'
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*
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* const S1 = pipe(S.Semigroup, intercalate(' + '))
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*
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* assert.strictEqual(S1.concat('a', 'b'), 'a + b')
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*
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* @since 2.10.0
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*/
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export var intercalate = function (middle) {
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return function (S) { return ({
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concat: function (x, y) { return S.concat(x, S.concat(middle, y)); }
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}); };
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};
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// -------------------------------------------------------------------------------------
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// instances
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// -------------------------------------------------------------------------------------
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/**
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* Always return the first argument.
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*
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* @example
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* import * as S from 'fp-ts/Semigroup'
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*
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* assert.deepStrictEqual(S.first<number>().concat(1, 2), 1)
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*
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* @category instances
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* @since 2.10.0
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*/
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export var first = function () { return ({ concat: identity }); };
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/**
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* Always return the last argument.
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*
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* @example
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* import * as S from 'fp-ts/Semigroup'
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*
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* assert.deepStrictEqual(S.last<number>().concat(1, 2), 2)
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*
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* @category instances
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* @since 2.10.0
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*/
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export var last = function () { return ({ concat: function (_, y) { return y; } }); };
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// -------------------------------------------------------------------------------------
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// utils
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// -------------------------------------------------------------------------------------
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/**
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* Given a sequence of `as`, concat them and return the total.
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*
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* If `as` is empty, return the provided `startWith` value.
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*
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* @example
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* import { concatAll } from 'fp-ts/Semigroup'
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* import * as N from 'fp-ts/number'
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*
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* const sum = concatAll(N.SemigroupSum)(0)
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*
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* assert.deepStrictEqual(sum([1, 2, 3]), 6)
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* assert.deepStrictEqual(sum([]), 0)
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*
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* @since 2.10.0
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*/
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export var concatAll = M.concatAll;
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// -------------------------------------------------------------------------------------
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// deprecated
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// -------------------------------------------------------------------------------------
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/**
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* Use `void` module instead.
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*
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* @category zone of death
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* @since 2.0.0
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* @deprecated
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*/
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export var semigroupVoid = constant(undefined);
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/**
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* Use [`getAssignSemigroup`](./struct.ts.html#getAssignSemigroup) instead.
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*
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* @category zone of death
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* @since 2.0.0
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* @deprecated
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*/
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export var getObjectSemigroup = function () { return ({
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concat: function (first, second) { return Object.assign({}, first, second); }
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}); };
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/**
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* Use [`last`](#last) instead.
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*
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* @category zone of death
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* @since 2.0.0
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* @deprecated
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*/
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export var getLastSemigroup = last;
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/**
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* Use [`first`](#first) instead.
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*
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* @category zone of death
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* @since 2.0.0
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* @deprecated
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*/
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export var getFirstSemigroup = first;
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/**
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* Use [`tuple`](#tuple) instead.
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*
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* @category zone of death
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* @since 2.0.0
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* @deprecated
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*/
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export var getTupleSemigroup = tuple;
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/**
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* Use [`struct`](#struct) instead.
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*
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* @category zone of death
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* @since 2.0.0
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* @deprecated
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*/
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export var getStructSemigroup = struct;
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/**
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* Use [`reverse`](#reverse) instead.
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*
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* @category zone of death
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* @since 2.0.0
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* @deprecated
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*/
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export var getDualSemigroup = reverse;
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/**
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* Use [`max`](#max) instead.
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*
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* @category zone of death
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* @since 2.0.0
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* @deprecated
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*/
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export var getJoinSemigroup = max;
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/**
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* Use [`min`](#min) instead.
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*
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* @category zone of death
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* @since 2.0.0
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* @deprecated
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*/
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export var getMeetSemigroup = min;
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/**
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* Use [`intercalate`](#intercalate) instead.
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*
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* @category zone of death
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* @since 2.5.0
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* @deprecated
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*/
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export var getIntercalateSemigroup = intercalate;
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export function fold(S) {
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var concatAllS = concatAll(S);
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return function (startWith, as) { return (as === undefined ? concatAllS(startWith) : concatAllS(startWith)(as)); };
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}
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/**
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* Use [`SemigroupAll`](./boolean.ts.html#SemigroupAll) instead.
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*
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* @category zone of death
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* @since 2.0.0
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* @deprecated
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*/
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export var semigroupAll = {
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concat: function (x, y) { return x && y; }
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};
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/**
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* Use [`SemigroupAny`](./boolean.ts.html#SemigroupAny) instead.
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*
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* @category zone of death
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* @since 2.0.0
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* @deprecated
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*/
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export var semigroupAny = {
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concat: function (x, y) { return x || y; }
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};
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/**
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* Use [`getSemigroup`](./function.ts.html#getSemigroup) instead.
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*
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* @category zone of death
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* @since 2.0.0
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* @deprecated
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*/
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export var getFunctionSemigroup = getSemigroup;
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/**
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* Use [`Semigroup`](./string.ts.html#Semigroup) instead.
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*
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* @category zone of death
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* @since 2.0.0
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* @deprecated
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*/
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export var semigroupString = {
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concat: function (x, y) { return x + y; }
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};
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/**
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* Use [`SemigroupSum`](./number.ts.html#SemigroupSum) instead.
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*
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* @category zone of death
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* @since 2.0.0
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* @deprecated
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*/
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export var semigroupSum = {
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concat: function (x, y) { return x + y; }
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};
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/**
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* Use [`SemigroupProduct`](./number.ts.html#SemigroupProduct) instead.
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*
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* @category zone of death
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* @since 2.0.0
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* @deprecated
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*/
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export var semigroupProduct = {
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concat: function (x, y) { return x * y; }
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};
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