|
- import { getApplicativeMonoid } from './Applicative';
- import { apFirst as apFirst_, apS as apS_, apSecond as apSecond_, getApplySemigroup as getApplySemigroup_ } from './Apply';
- import { bind as bind_, chainFirst as chainFirst_ } from './Chain';
- import { tailRec } from './ChainRec';
- import { chainOptionK as chainOptionK_, filterOrElse as filterOrElse_, fromOption as fromOption_, fromOptionK as fromOptionK_, fromPredicate as fromPredicate_ } from './FromEither';
- import { flow, identity, pipe } from './function';
- import { bindTo as bindTo_, flap as flap_, let as let__ } from './Functor';
- import * as _ from './internal';
- import { separated } from './Separated';
- import { wiltDefault, witherDefault } from './Witherable';
- // -------------------------------------------------------------------------------------
- // constructors
- // -------------------------------------------------------------------------------------
- /**
- * Constructs a new `Either` holding a `Left` value. This usually represents a failure, due to the right-bias of this
- * structure.
- *
- * @category constructors
- * @since 2.0.0
- */
- export var left = _.left;
- /**
- * Constructs a new `Either` holding a `Right` value. This usually represents a successful value due to the right bias
- * of this structure.
- *
- * @category constructors
- * @since 2.0.0
- */
- export var right = _.right;
- var _map = function (fa, f) { return pipe(fa, map(f)); };
- var _ap = function (fab, fa) { return pipe(fab, ap(fa)); };
- /* istanbul ignore next */
- var _chain = function (ma, f) { return pipe(ma, chain(f)); };
- /* istanbul ignore next */
- var _reduce = function (fa, b, f) { return pipe(fa, reduce(b, f)); };
- /* istanbul ignore next */
- var _foldMap = function (M) { return function (fa, f) {
- var foldMapM = foldMap(M);
- return pipe(fa, foldMapM(f));
- }; };
- /* istanbul ignore next */
- var _reduceRight = function (fa, b, f) { return pipe(fa, reduceRight(b, f)); };
- var _traverse = function (F) {
- var traverseF = traverse(F);
- return function (ta, f) { return pipe(ta, traverseF(f)); };
- };
- var _bimap = function (fa, f, g) { return pipe(fa, bimap(f, g)); };
- var _mapLeft = function (fa, f) { return pipe(fa, mapLeft(f)); };
- /* istanbul ignore next */
- var _alt = function (fa, that) { return pipe(fa, alt(that)); };
- /* istanbul ignore next */
- var _extend = function (wa, f) { return pipe(wa, extend(f)); };
- var _chainRec = function (a, f) {
- return tailRec(f(a), function (e) {
- return isLeft(e) ? right(left(e.left)) : isLeft(e.right) ? left(f(e.right.left)) : right(right(e.right.right));
- });
- };
- /**
- * @category type lambdas
- * @since 2.0.0
- */
- export var URI = 'Either';
- /**
- * @category instances
- * @since 2.0.0
- */
- export var getShow = function (SE, SA) { return ({
- show: function (ma) { return (isLeft(ma) ? "left(".concat(SE.show(ma.left), ")") : "right(".concat(SA.show(ma.right), ")")); }
- }); };
- /**
- * @category instances
- * @since 2.0.0
- */
- export var getEq = function (EL, EA) { return ({
- equals: function (x, y) {
- return x === y || (isLeft(x) ? isLeft(y) && EL.equals(x.left, y.left) : isRight(y) && EA.equals(x.right, y.right));
- }
- }); };
- /**
- * Semigroup returning the left-most non-`Left` value. If both operands are `Right`s then the inner values are
- * concatenated using the provided `Semigroup`
- *
- * @example
- * import { getSemigroup, left, right } from 'fp-ts/Either'
- * import { SemigroupSum } from 'fp-ts/number'
- *
- * const S = getSemigroup<string, number>(SemigroupSum)
- * assert.deepStrictEqual(S.concat(left('a'), left('b')), left('a'))
- * assert.deepStrictEqual(S.concat(left('a'), right(2)), right(2))
- * assert.deepStrictEqual(S.concat(right(1), left('b')), right(1))
- * assert.deepStrictEqual(S.concat(right(1), right(2)), right(3))
- *
- * @category instances
- * @since 2.0.0
- */
- export var getSemigroup = function (S) { return ({
- concat: function (x, y) { return (isLeft(y) ? x : isLeft(x) ? y : right(S.concat(x.right, y.right))); }
- }); };
- /**
- * Builds a `Compactable` instance for `Either` given `Monoid` for the left side.
- *
- * @category filtering
- * @since 2.10.0
- */
- export var getCompactable = function (M) {
- var empty = left(M.empty);
- return {
- URI: URI,
- _E: undefined,
- compact: function (ma) { return (isLeft(ma) ? ma : ma.right._tag === 'None' ? empty : right(ma.right.value)); },
- separate: function (ma) {
- return isLeft(ma)
- ? separated(ma, ma)
- : isLeft(ma.right)
- ? separated(right(ma.right.left), empty)
- : separated(empty, right(ma.right.right));
- }
- };
- };
- /**
- * Builds a `Filterable` instance for `Either` given `Monoid` for the left side
- *
- * @category filtering
- * @since 2.10.0
- */
- export var getFilterable = function (M) {
- var empty = left(M.empty);
- var _a = getCompactable(M), compact = _a.compact, separate = _a.separate;
- var filter = function (ma, predicate) {
- return isLeft(ma) ? ma : predicate(ma.right) ? ma : empty;
- };
- var partition = function (ma, p) {
- return isLeft(ma)
- ? separated(ma, ma)
- : p(ma.right)
- ? separated(empty, right(ma.right))
- : separated(right(ma.right), empty);
- };
- return {
- URI: URI,
- _E: undefined,
- map: _map,
- compact: compact,
- separate: separate,
- filter: filter,
- filterMap: function (ma, f) {
- if (isLeft(ma)) {
- return ma;
- }
- var ob = f(ma.right);
- return ob._tag === 'None' ? empty : right(ob.value);
- },
- partition: partition,
- partitionMap: function (ma, f) {
- if (isLeft(ma)) {
- return separated(ma, ma);
- }
- var e = f(ma.right);
- return isLeft(e) ? separated(right(e.left), empty) : separated(empty, right(e.right));
- }
- };
- };
- /**
- * Builds `Witherable` instance for `Either` given `Monoid` for the left side
- *
- * @category filtering
- * @since 2.0.0
- */
- export var getWitherable = function (M) {
- var F_ = getFilterable(M);
- var C = getCompactable(M);
- return {
- URI: URI,
- _E: undefined,
- map: _map,
- compact: F_.compact,
- separate: F_.separate,
- filter: F_.filter,
- filterMap: F_.filterMap,
- partition: F_.partition,
- partitionMap: F_.partitionMap,
- traverse: _traverse,
- sequence: sequence,
- reduce: _reduce,
- foldMap: _foldMap,
- reduceRight: _reduceRight,
- wither: witherDefault(Traversable, C),
- wilt: wiltDefault(Traversable, C)
- };
- };
- /**
- * The default [`Applicative`](#applicative) instance returns the first error, if you want to
- * get all errors you need to provide a way to concatenate them via a `Semigroup`.
- *
- * @example
- * import * as A from 'fp-ts/Apply'
- * import * as E from 'fp-ts/Either'
- * import { pipe } from 'fp-ts/function'
- * import * as S from 'fp-ts/Semigroup'
- * import * as string from 'fp-ts/string'
- *
- * const parseString = (u: unknown): E.Either<string, string> =>
- * typeof u === 'string' ? E.right(u) : E.left('not a string')
- *
- * const parseNumber = (u: unknown): E.Either<string, number> =>
- * typeof u === 'number' ? E.right(u) : E.left('not a number')
- *
- * interface Person {
- * readonly name: string
- * readonly age: number
- * }
- *
- * const parsePerson = (
- * input: Record<string, unknown>
- * ): E.Either<string, Person> =>
- * pipe(
- * E.Do,
- * E.apS('name', parseString(input.name)),
- * E.apS('age', parseNumber(input.age))
- * )
- *
- * assert.deepStrictEqual(parsePerson({}), E.left('not a string')) // <= first error
- *
- * const Applicative = E.getApplicativeValidation(
- * pipe(string.Semigroup, S.intercalate(', '))
- * )
- *
- * const apS = A.apS(Applicative)
- *
- * const parsePersonAll = (
- * input: Record<string, unknown>
- * ): E.Either<string, Person> =>
- * pipe(
- * E.Do,
- * apS('name', parseString(input.name)),
- * apS('age', parseNumber(input.age))
- * )
- *
- * assert.deepStrictEqual(parsePersonAll({}), E.left('not a string, not a number')) // <= all errors
- *
- * @category error handling
- * @since 2.7.0
- */
- export var getApplicativeValidation = function (SE) { return ({
- URI: URI,
- _E: undefined,
- map: _map,
- ap: function (fab, fa) {
- return isLeft(fab)
- ? isLeft(fa)
- ? left(SE.concat(fab.left, fa.left))
- : fab
- : isLeft(fa)
- ? fa
- : right(fab.right(fa.right));
- },
- of: of
- }); };
- /**
- * The default [`Alt`](#alt) instance returns the last error, if you want to
- * get all errors you need to provide a way to concatenate them via a `Semigroup`.
- *
- * @example
- * import * as E from 'fp-ts/Either'
- * import { pipe } from 'fp-ts/function'
- * import * as S from 'fp-ts/Semigroup'
- * import * as string from 'fp-ts/string'
- *
- * const parseString = (u: unknown): E.Either<string, string> =>
- * typeof u === 'string' ? E.right(u) : E.left('not a string')
- *
- * const parseNumber = (u: unknown): E.Either<string, number> =>
- * typeof u === 'number' ? E.right(u) : E.left('not a number')
- *
- * const parse = (u: unknown): E.Either<string, string | number> =>
- * pipe(
- * parseString(u),
- * E.alt<string, string | number>(() => parseNumber(u))
- * )
- *
- * assert.deepStrictEqual(parse(true), E.left('not a number')) // <= last error
- *
- * const Alt = E.getAltValidation(pipe(string.Semigroup, S.intercalate(', ')))
- *
- * const parseAll = (u: unknown): E.Either<string, string | number> =>
- * Alt.alt<string | number>(parseString(u), () => parseNumber(u))
- *
- * assert.deepStrictEqual(parseAll(true), E.left('not a string, not a number')) // <= all errors
- *
- * @category error handling
- * @since 2.7.0
- */
- export var getAltValidation = function (SE) { return ({
- URI: URI,
- _E: undefined,
- map: _map,
- alt: function (me, that) {
- if (isRight(me)) {
- return me;
- }
- var ea = that();
- return isLeft(ea) ? left(SE.concat(me.left, ea.left)) : ea;
- }
- }); };
- /**
- * @category mapping
- * @since 2.0.0
- */
- export var map = function (f) { return function (fa) {
- return isLeft(fa) ? fa : right(f(fa.right));
- }; };
- /**
- * @category instances
- * @since 2.7.0
- */
- export var Functor = {
- URI: URI,
- map: _map
- };
- /**
- * @category constructors
- * @since 2.7.0
- */
- export var of = right;
- /**
- * @category instances
- * @since 2.10.0
- */
- export var Pointed = {
- URI: URI,
- of: of
- };
- /**
- * Less strict version of [`ap`](#ap).
- *
- * The `W` suffix (short for **W**idening) means that the error types will be merged.
- *
- * @since 2.8.0
- */
- export var apW = function (fa) { return function (fab) {
- return isLeft(fab) ? fab : isLeft(fa) ? fa : right(fab.right(fa.right));
- }; };
- /**
- * @since 2.0.0
- */
- export var ap = apW;
- /**
- * @category instances
- * @since 2.10.0
- */
- export var Apply = {
- URI: URI,
- map: _map,
- ap: _ap
- };
- /**
- * @category instances
- * @since 2.7.0
- */
- export var Applicative = {
- URI: URI,
- map: _map,
- ap: _ap,
- of: of
- };
- /**
- * Less strict version of [`chain`](#chain).
- *
- * The `W` suffix (short for **W**idening) means that the error types will be merged.
- *
- * @example
- * import * as E from 'fp-ts/Either'
- * import { pipe } from 'fp-ts/function'
- *
- * const e1: E.Either<string, number> = E.right(1)
- * const e2: E.Either<number, number> = E.right(2)
- *
- * export const result1 = pipe(
- * // @ts-expect-error
- * e1,
- * E.chain(() => e2)
- * )
- *
- * // merged error types -----v-------------v
- * // const result2: E.Either<string | number, number>
- * export const result2 = pipe(
- * e1, // no error
- * E.chainW(() => e2)
- * )
- *
- * @category sequencing
- * @since 2.6.0
- */
- export var chainW = function (f) {
- return function (ma) {
- return isLeft(ma) ? ma : f(ma.right);
- };
- };
- /**
- * Composes computations in sequence, using the return value of one computation to determine the next computation.
- *
- * @category sequencing
- * @since 2.0.0
- */
- export var chain = chainW;
- /**
- * @category instances
- * @since 2.10.0
- */
- export var Chain = {
- URI: URI,
- map: _map,
- ap: _ap,
- chain: _chain
- };
- /**
- * @category instances
- * @since 2.7.0
- */
- export var Monad = {
- URI: URI,
- map: _map,
- ap: _ap,
- of: of,
- chain: _chain
- };
- /**
- * Left-associative fold of a structure.
- *
- * @example
- * import { pipe } from 'fp-ts/function'
- * import * as E from 'fp-ts/Either'
- *
- * const startWith = 'prefix'
- * const concat = (a: string, b: string) => `${a}:${b}`
- *
- * assert.deepStrictEqual(
- * pipe(E.right('a'), E.reduce(startWith, concat)),
- * 'prefix:a'
- * )
- *
- * assert.deepStrictEqual(
- * pipe(E.left('e'), E.reduce(startWith, concat)),
- * 'prefix'
- * )
- *
- * @category folding
- * @since 2.0.0
- */
- export var reduce = function (b, f) { return function (fa) {
- return isLeft(fa) ? b : f(b, fa.right);
- }; };
- /**
- * Map each element of the structure to a monoid, and combine the results.
- *
- * @example
- * import { pipe } from 'fp-ts/function'
- * import * as E from 'fp-ts/Either'
- * import * as S from 'fp-ts/string'
- *
- * const yell = (a: string) => `${a}!`
- *
- * assert.deepStrictEqual(
- * pipe(E.right('a'), E.foldMap(S.Monoid)(yell)),
- * 'a!'
- * )
- *
- * assert.deepStrictEqual(
- * pipe(E.left('e'), E.foldMap(S.Monoid)(yell)),
- * S.Monoid.empty
- * )
- *
- * @category folding
- * @since 2.0.0
- */
- export var foldMap = function (M) { return function (f) { return function (fa) {
- return isLeft(fa) ? M.empty : f(fa.right);
- }; }; };
- /**
- * Right-associative fold of a structure.
- *
- * @example
- * import { pipe } from 'fp-ts/function'
- * import * as E from 'fp-ts/Either'
- *
- * const startWith = 'postfix'
- * const concat = (a: string, b: string) => `${a}:${b}`
- *
- * assert.deepStrictEqual(
- * pipe(E.right('a'), E.reduceRight(startWith, concat)),
- * 'a:postfix'
- * )
- *
- * assert.deepStrictEqual(
- * pipe(E.left('e'), E.reduceRight(startWith, concat)),
- * 'postfix'
- * )
- *
- * @category folding
- * @since 2.0.0
- */
- export var reduceRight = function (b, f) { return function (fa) {
- return isLeft(fa) ? b : f(fa.right, b);
- }; };
- /**
- * @category instances
- * @since 2.7.0
- */
- export var Foldable = {
- URI: URI,
- reduce: _reduce,
- foldMap: _foldMap,
- reduceRight: _reduceRight
- };
- /**
- * Map each element of a structure to an action, evaluate these actions from left to right, and collect the results.
- *
- * @example
- * import { pipe } from 'fp-ts/function'
- * import * as RA from 'fp-ts/ReadonlyArray'
- * import * as E from 'fp-ts/Either'
- * import * as O from 'fp-ts/Option'
- *
- * assert.deepStrictEqual(
- * pipe(E.right(['a']), E.traverse(O.Applicative)(RA.head)),
- * O.some(E.right('a'))
- * )
- *
- * assert.deepStrictEqual(
- * pipe(E.right([]), E.traverse(O.Applicative)(RA.head)),
- * O.none
- * )
- *
- * @category traversing
- * @since 2.6.3
- */
- export var traverse = function (F) {
- return function (f) {
- return function (ta) {
- return isLeft(ta) ? F.of(left(ta.left)) : F.map(f(ta.right), right);
- };
- };
- };
- /**
- * Evaluate each monadic action in the structure from left to right, and collect the results.
- *
- * @example
- * import { pipe } from 'fp-ts/function'
- * import * as E from 'fp-ts/Either'
- * import * as O from 'fp-ts/Option'
- *
- * assert.deepStrictEqual(
- * pipe(E.right(O.some('a')), E.sequence(O.Applicative)),
- * O.some(E.right('a'))
- * )
- *
- * assert.deepStrictEqual(
- * pipe(E.right(O.none), E.sequence(O.Applicative)),
- * O.none
- * )
- *
- * @category traversing
- * @since 2.6.3
- */
- export var sequence = function (F) {
- return function (ma) {
- return isLeft(ma) ? F.of(left(ma.left)) : F.map(ma.right, right);
- };
- };
- /**
- * @category instances
- * @since 2.7.0
- */
- export var Traversable = {
- URI: URI,
- map: _map,
- reduce: _reduce,
- foldMap: _foldMap,
- reduceRight: _reduceRight,
- traverse: _traverse,
- sequence: sequence
- };
- /**
- * Map a pair of functions over the two type arguments of the bifunctor.
- *
- * @category mapping
- * @since 2.0.0
- */
- export var bimap = function (f, g) { return function (fa) {
- return isLeft(fa) ? left(f(fa.left)) : right(g(fa.right));
- }; };
- /**
- * Map a function over the first type argument of a bifunctor.
- *
- * @category error handling
- * @since 2.0.0
- */
- export var mapLeft = function (f) { return function (fa) {
- return isLeft(fa) ? left(f(fa.left)) : fa;
- }; };
- /**
- * @category instances
- * @since 2.7.0
- */
- export var Bifunctor = {
- URI: URI,
- bimap: _bimap,
- mapLeft: _mapLeft
- };
- /**
- * Less strict version of [`alt`](#alt).
- *
- * The `W` suffix (short for **W**idening) means that the error and the return types will be merged.
- *
- * @category error handling
- * @since 2.9.0
- */
- export var altW = function (that) { return function (fa) {
- return isLeft(fa) ? that() : fa;
- }; };
- /**
- * Identifies an associative operation on a type constructor. It is similar to `Semigroup`, except that it applies to
- * types of kind `* -> *`.
- *
- * In case of `Either` returns the left-most non-`Left` value (or the right-most `Left` value if both values are `Left`).
- *
- * | x | y | pipe(x, alt(() => y) |
- * | -------- | -------- | -------------------- |
- * | left(a) | left(b) | left(b) |
- * | left(a) | right(2) | right(2) |
- * | right(1) | left(b) | right(1) |
- * | right(1) | right(2) | right(1) |
- *
- * @example
- * import * as E from 'fp-ts/Either'
- * import { pipe } from 'fp-ts/function'
- *
- * assert.deepStrictEqual(
- * pipe(
- * E.left('a'),
- * E.alt(() => E.left('b'))
- * ),
- * E.left('b')
- * )
- * assert.deepStrictEqual(
- * pipe(
- * E.left('a'),
- * E.alt(() => E.right(2))
- * ),
- * E.right(2)
- * )
- * assert.deepStrictEqual(
- * pipe(
- * E.right(1),
- * E.alt(() => E.left('b'))
- * ),
- * E.right(1)
- * )
- * assert.deepStrictEqual(
- * pipe(
- * E.right(1),
- * E.alt(() => E.right(2))
- * ),
- * E.right(1)
- * )
- *
- * @category error handling
- * @since 2.0.0
- */
- export var alt = altW;
- /**
- * @category instances
- * @since 2.7.0
- */
- export var Alt = {
- URI: URI,
- map: _map,
- alt: _alt
- };
- /**
- * @since 2.0.0
- */
- export var extend = function (f) { return function (wa) {
- return isLeft(wa) ? wa : right(f(wa));
- }; };
- /**
- * @category instances
- * @since 2.7.0
- */
- export var Extend = {
- URI: URI,
- map: _map,
- extend: _extend
- };
- /**
- * @category instances
- * @since 2.7.0
- */
- export var ChainRec = {
- URI: URI,
- map: _map,
- ap: _ap,
- chain: _chain,
- chainRec: _chainRec
- };
- /**
- * @since 2.6.3
- */
- export var throwError = left;
- /**
- * @category instances
- * @since 2.7.0
- */
- export var MonadThrow = {
- URI: URI,
- map: _map,
- ap: _ap,
- of: of,
- chain: _chain,
- throwError: throwError
- };
- /**
- * @category instances
- * @since 2.10.0
- */
- export var FromEither = {
- URI: URI,
- fromEither: identity
- };
- /**
- * @example
- * import { fromPredicate, left, right } from 'fp-ts/Either'
- * import { pipe } from 'fp-ts/function'
- *
- * assert.deepStrictEqual(
- * pipe(
- * 1,
- * fromPredicate(
- * (n) => n > 0,
- * () => 'error'
- * )
- * ),
- * right(1)
- * )
- * assert.deepStrictEqual(
- * pipe(
- * -1,
- * fromPredicate(
- * (n) => n > 0,
- * () => 'error'
- * )
- * ),
- * left('error')
- * )
- *
- * @category lifting
- * @since 2.0.0
- */
- export var fromPredicate = /*#__PURE__*/ fromPredicate_(FromEither);
- // -------------------------------------------------------------------------------------
- // conversions
- // -------------------------------------------------------------------------------------
- /**
- * @example
- * import * as E from 'fp-ts/Either'
- * import { pipe } from 'fp-ts/function'
- * import * as O from 'fp-ts/Option'
- *
- * assert.deepStrictEqual(
- * pipe(
- * O.some(1),
- * E.fromOption(() => 'error')
- * ),
- * E.right(1)
- * )
- * assert.deepStrictEqual(
- * pipe(
- * O.none,
- * E.fromOption(() => 'error')
- * ),
- * E.left('error')
- * )
- *
- * @category conversions
- * @since 2.0.0
- */
- export var fromOption =
- /*#__PURE__*/ fromOption_(FromEither);
- // -------------------------------------------------------------------------------------
- // refinements
- // -------------------------------------------------------------------------------------
- /**
- * Returns `true` if the either is an instance of `Left`, `false` otherwise.
- *
- * @category refinements
- * @since 2.0.0
- */
- export var isLeft = _.isLeft;
- /**
- * Returns `true` if the either is an instance of `Right`, `false` otherwise.
- *
- * @category refinements
- * @since 2.0.0
- */
- export var isRight = _.isRight;
- /**
- * Less strict version of [`match`](#match).
- *
- * The `W` suffix (short for **W**idening) means that the handler return types will be merged.
- *
- * @category pattern matching
- * @since 2.10.0
- */
- export var matchW = function (onLeft, onRight) {
- return function (ma) {
- return isLeft(ma) ? onLeft(ma.left) : onRight(ma.right);
- };
- };
- /**
- * Alias of [`matchW`](#matchw).
- *
- * @category pattern matching
- * @since 2.10.0
- */
- export var foldW = matchW;
- /**
- * Takes two functions and an `Either` value, if the value is a `Left` the inner value is applied to the first function,
- * if the value is a `Right` the inner value is applied to the second function.
- *
- * @example
- * import { match, left, right } from 'fp-ts/Either'
- * import { pipe } from 'fp-ts/function'
- *
- * function onLeft(errors: Array<string>): string {
- * return `Errors: ${errors.join(', ')}`
- * }
- *
- * function onRight(value: number): string {
- * return `Ok: ${value}`
- * }
- *
- * assert.strictEqual(
- * pipe(
- * right(1),
- * match(onLeft, onRight)
- * ),
- * 'Ok: 1'
- * )
- * assert.strictEqual(
- * pipe(
- * left(['error 1', 'error 2']),
- * match(onLeft, onRight)
- * ),
- * 'Errors: error 1, error 2'
- * )
- *
- * @category pattern matching
- * @since 2.10.0
- */
- export var match = matchW;
- /**
- * Alias of [`match`](#match).
- *
- * @category pattern matching
- * @since 2.0.0
- */
- export var fold = match;
- /**
- * Less strict version of [`getOrElse`](#getorelse).
- *
- * The `W` suffix (short for **W**idening) means that the handler return type will be merged.
- *
- * @category error handling
- * @since 2.6.0
- */
- export var getOrElseW = function (onLeft) {
- return function (ma) {
- return isLeft(ma) ? onLeft(ma.left) : ma.right;
- };
- };
- /**
- * Returns the wrapped value if it's a `Right` or a default value if is a `Left`.
- *
- * @example
- * import { getOrElse, left, right } from 'fp-ts/Either'
- * import { pipe } from 'fp-ts/function'
- *
- * assert.deepStrictEqual(
- * pipe(
- * right(1),
- * getOrElse(() => 0)
- * ),
- * 1
- * )
- * assert.deepStrictEqual(
- * pipe(
- * left('error'),
- * getOrElse(() => 0)
- * ),
- * 0
- * )
- *
- * @category error handling
- * @since 2.0.0
- */
- export var getOrElse = getOrElseW;
- // -------------------------------------------------------------------------------------
- // combinators
- // -------------------------------------------------------------------------------------
- /**
- * @category mapping
- * @since 2.10.0
- */
- export var flap = /*#__PURE__*/ flap_(Functor);
- /**
- * Combine two effectful actions, keeping only the result of the first.
- *
- * @since 2.0.0
- */
- export var apFirst = /*#__PURE__*/ apFirst_(Apply);
- /**
- * Less strict version of [`apFirst`](#apfirst)
- *
- * The `W` suffix (short for **W**idening) means that the error types will be merged.
- *
- * @since 2.12.0
- */
- export var apFirstW = apFirst;
- /**
- * Combine two effectful actions, keeping only the result of the second.
- *
- * @since 2.0.0
- */
- export var apSecond = /*#__PURE__*/ apSecond_(Apply);
- /**
- * Less strict version of [`apSecond`](#apsecond)
- *
- * The `W` suffix (short for **W**idening) means that the error types will be merged.
- *
- * @since 2.12.0
- */
- export var apSecondW = apSecond;
- /**
- * Composes computations in sequence, using the return value of one computation to determine the next computation and
- * keeping only the result of the first.
- *
- * @category sequencing
- * @since 2.0.0
- */
- export var chainFirst =
- /*#__PURE__*/ chainFirst_(Chain);
- /**
- * Less strict version of [`chainFirst`](#chainfirst)
- *
- * The `W` suffix (short for **W**idening) means that the error types will be merged.
- *
- * @category sequencing
- * @since 2.8.0
- */
- export var chainFirstW = chainFirst;
- /**
- * Less strict version of [`flatten`](#flatten).
- *
- * The `W` suffix (short for **W**idening) means that the error types will be merged.
- *
- * @category sequencing
- * @since 2.11.0
- */
- export var flattenW =
- /*#__PURE__*/ chainW(identity);
- /**
- * The `flatten` function is the conventional monad join operator. It is used to remove one level of monadic structure, projecting its bound argument into the outer level.
- *
- * @example
- * import * as E from 'fp-ts/Either'
- *
- * assert.deepStrictEqual(E.flatten(E.right(E.right('a'))), E.right('a'))
- * assert.deepStrictEqual(E.flatten(E.right(E.left('e'))), E.left('e'))
- * assert.deepStrictEqual(E.flatten(E.left('e')), E.left('e'))
- *
- * @category sequencing
- * @since 2.0.0
- */
- export var flatten = flattenW;
- /**
- * @since 2.0.0
- */
- export var duplicate = /*#__PURE__*/ extend(identity);
- /**
- * @category lifting
- * @since 2.10.0
- */
- export var fromOptionK =
- /*#__PURE__*/ fromOptionK_(FromEither);
- /**
- * @category sequencing
- * @since 2.11.0
- */
- export var chainOptionK = /*#__PURE__*/ chainOptionK_(FromEither, Chain);
- /**
- * @example
- * import * as E from 'fp-ts/Either'
- * import { pipe } from 'fp-ts/function'
- *
- * assert.deepStrictEqual(
- * pipe(
- * E.right(1),
- * E.filterOrElse(
- * (n) => n > 0,
- * () => 'error'
- * )
- * ),
- * E.right(1)
- * )
- * assert.deepStrictEqual(
- * pipe(
- * E.right(-1),
- * E.filterOrElse(
- * (n) => n > 0,
- * () => 'error'
- * )
- * ),
- * E.left('error')
- * )
- * assert.deepStrictEqual(
- * pipe(
- * E.left('a'),
- * E.filterOrElse(
- * (n) => n > 0,
- * () => 'error'
- * )
- * ),
- * E.left('a')
- * )
- *
- * @category filtering
- * @since 2.0.0
- */
- export var filterOrElse = /*#__PURE__*/ filterOrElse_(FromEither, Chain);
- /**
- * Less strict version of [`filterOrElse`](#filterorelse).
- *
- * The `W` suffix (short for **W**idening) means that the error types will be merged.
- *
- * @category filtering
- * @since 2.9.0
- */
- export var filterOrElseW = filterOrElse;
- /**
- * Returns a `Right` if is a `Left` (and vice versa).
- *
- * @since 2.0.0
- */
- export var swap = function (ma) { return (isLeft(ma) ? right(ma.left) : left(ma.right)); };
- /**
- * Less strict version of [`orElse`](#orelse).
- *
- * The `W` suffix (short for **W**idening) means that the return types will be merged.
- *
- * @category error handling
- * @since 2.10.0
- */
- export var orElseW = function (onLeft) {
- return function (ma) {
- return isLeft(ma) ? onLeft(ma.left) : ma;
- };
- };
- /**
- * Useful for recovering from errors.
- *
- * @category error handling
- * @since 2.0.0
- */
- export var orElse = orElseW;
- /**
- * Takes a default and a nullable value, if the value is not nully, turn it into a `Right`, if the value is nully use
- * the provided default as a `Left`.
- *
- * @example
- * import { fromNullable, left, right } from 'fp-ts/Either'
- *
- * const parse = fromNullable('nully')
- *
- * assert.deepStrictEqual(parse(1), right(1))
- * assert.deepStrictEqual(parse(null), left('nully'))
- *
- * @category conversions
- * @since 2.0.0
- */
- export var fromNullable = function (e) {
- return function (a) {
- return a == null ? left(e) : right(a);
- };
- };
- /**
- * Constructs a new `Either` from a function that might throw.
- *
- * See also [`tryCatchK`](#trycatchk).
- *
- * @example
- * import * as E from 'fp-ts/Either'
- *
- * const unsafeHead = <A>(as: ReadonlyArray<A>): A => {
- * if (as.length > 0) {
- * return as[0]
- * } else {
- * throw new Error('empty array')
- * }
- * }
- *
- * const head = <A>(as: ReadonlyArray<A>): E.Either<Error, A> =>
- * E.tryCatch(() => unsafeHead(as), e => (e instanceof Error ? e : new Error('unknown error')))
- *
- * assert.deepStrictEqual(head([]), E.left(new Error('empty array')))
- * assert.deepStrictEqual(head([1, 2, 3]), E.right(1))
- *
- * @category interop
- * @since 2.0.0
- */
- export var tryCatch = function (f, onThrow) {
- try {
- return right(f());
- }
- catch (e) {
- return left(onThrow(e));
- }
- };
- /**
- * Converts a function that may throw to one returning a `Either`.
- *
- * @category interop
- * @since 2.10.0
- */
- export var tryCatchK = function (f, onThrow) {
- return function () {
- var a = [];
- for (var _i = 0; _i < arguments.length; _i++) {
- a[_i] = arguments[_i];
- }
- return tryCatch(function () { return f.apply(void 0, a); }, onThrow);
- };
- };
- /**
- * @category lifting
- * @since 2.9.0
- */
- export var fromNullableK = function (e) {
- var from = fromNullable(e);
- return function (f) { return flow(f, from); };
- };
- /**
- * @category sequencing
- * @since 2.9.0
- */
- export var chainNullableK = function (e) {
- var from = fromNullableK(e);
- return function (f) { return chain(from(f)); };
- };
- /**
- * @category conversions
- * @since 2.10.0
- */
- export var toUnion = /*#__PURE__*/ foldW(identity, identity);
- // -------------------------------------------------------------------------------------
- // utils
- // -------------------------------------------------------------------------------------
- /**
- * Default value for the `onError` argument of `tryCatch`
- *
- * @since 2.0.0
- */
- export function toError(e) {
- return e instanceof Error ? e : new Error(String(e));
- }
- export function elem(E) {
- return function (a, ma) {
- if (ma === undefined) {
- var elemE_1 = elem(E);
- return function (ma) { return elemE_1(a, ma); };
- }
- return isLeft(ma) ? false : E.equals(a, ma.right);
- };
- }
- /**
- * Returns `false` if `Left` or returns the result of the application of the given predicate to the `Right` value.
- *
- * @example
- * import { exists, left, right } from 'fp-ts/Either'
- *
- * const gt2 = exists((n: number) => n > 2)
- *
- * assert.strictEqual(gt2(left('a')), false)
- * assert.strictEqual(gt2(right(1)), false)
- * assert.strictEqual(gt2(right(3)), true)
- *
- * @since 2.0.0
- */
- export var exists = function (predicate) {
- return function (ma) {
- return isLeft(ma) ? false : predicate(ma.right);
- };
- };
- // -------------------------------------------------------------------------------------
- // do notation
- // -------------------------------------------------------------------------------------
- /**
- * @category do notation
- * @since 2.9.0
- */
- export var Do = /*#__PURE__*/ of(_.emptyRecord);
- /**
- * @category do notation
- * @since 2.8.0
- */
- export var bindTo = /*#__PURE__*/ bindTo_(Functor);
- var let_ = /*#__PURE__*/ let__(Functor);
- export {
- /**
- * @category do notation
- * @since 2.13.0
- */
- let_ as let };
- /**
- * @category do notation
- * @since 2.8.0
- */
- export var bind = /*#__PURE__*/ bind_(Chain);
- /**
- * The `W` suffix (short for **W**idening) means that the error types will be merged.
- *
- * @category do notation
- * @since 2.8.0
- */
- export var bindW = bind;
- /**
- * @category do notation
- * @since 2.8.0
- */
- export var apS = /*#__PURE__*/ apS_(Apply);
- /**
- * Less strict version of [`apS`](#aps).
- *
- * The `W` suffix (short for **W**idening) means that the error types will be merged.
- *
- * @category do notation
- * @since 2.8.0
- */
- export var apSW = apS;
- /**
- * @since 2.11.0
- */
- export var ApT = /*#__PURE__*/ of(_.emptyReadonlyArray);
- // -------------------------------------------------------------------------------------
- // array utils
- // -------------------------------------------------------------------------------------
- /**
- * Equivalent to `ReadonlyNonEmptyArray#traverseWithIndex(Applicative)`.
- *
- * @category traversing
- * @since 2.11.0
- */
- export var traverseReadonlyNonEmptyArrayWithIndex = function (f) {
- return function (as) {
- var e = f(0, _.head(as));
- if (isLeft(e)) {
- return e;
- }
- var out = [e.right];
- for (var i = 1; i < as.length; i++) {
- var e_1 = f(i, as[i]);
- if (isLeft(e_1)) {
- return e_1;
- }
- out.push(e_1.right);
- }
- return right(out);
- };
- };
- /**
- * Equivalent to `ReadonlyArray#traverseWithIndex(Applicative)`.
- *
- * @category traversing
- * @since 2.11.0
- */
- export var traverseReadonlyArrayWithIndex = function (f) {
- var g = traverseReadonlyNonEmptyArrayWithIndex(f);
- return function (as) { return (_.isNonEmpty(as) ? g(as) : ApT); };
- };
- /**
- * Equivalent to `ReadonlyArray#traverseWithIndex(Applicative)`.
- *
- * @category traversing
- * @since 2.9.0
- */
- export var traverseArrayWithIndex = traverseReadonlyArrayWithIndex;
- /**
- * Equivalent to `ReadonlyArray#traverse(Applicative)`.
- *
- * @category traversing
- * @since 2.9.0
- */
- export var traverseArray = function (f) { return traverseReadonlyArrayWithIndex(function (_, a) { return f(a); }); };
- /**
- * Equivalent to `ReadonlyArray#sequence(Applicative)`.
- *
- * @category traversing
- * @since 2.9.0
- */
- export var sequenceArray =
- /*#__PURE__*/ traverseArray(identity);
- /**
- * Use [`parse`](./Json.ts.html#parse) instead.
- *
- * @category zone of death
- * @since 2.0.0
- * @deprecated
- */
- export function parseJSON(s, onError) {
- return tryCatch(function () { return JSON.parse(s); }, onError);
- }
- /**
- * Use [`stringify`](./Json.ts.html#stringify) instead.
- *
- * @category zone of death
- * @since 2.0.0
- * @deprecated
- */
- export var stringifyJSON = function (u, onError) {
- return tryCatch(function () {
- var s = JSON.stringify(u);
- if (typeof s !== 'string') {
- throw new Error('Converting unsupported structure to JSON');
- }
- return s;
- }, onError);
- };
- /**
- * This instance is deprecated, use small, specific instances instead.
- * For example if a function needs a `Functor` instance, pass `E.Functor` instead of `E.either`
- * (where `E` is from `import E from 'fp-ts/Either'`)
- *
- * @category zone of death
- * @since 2.0.0
- * @deprecated
- */
- export var either = {
- URI: URI,
- map: _map,
- of: of,
- ap: _ap,
- chain: _chain,
- reduce: _reduce,
- foldMap: _foldMap,
- reduceRight: _reduceRight,
- traverse: _traverse,
- sequence: sequence,
- bimap: _bimap,
- mapLeft: _mapLeft,
- alt: _alt,
- extend: _extend,
- chainRec: _chainRec,
- throwError: throwError
- };
- /**
- * Use [`getApplySemigroup`](./Apply.ts.html#getapplysemigroup) instead.
- *
- * Semigroup returning the left-most `Left` value. If both operands are `Right`s then the inner values
- * are concatenated using the provided `Semigroup`
- *
- * @category zone of death
- * @since 2.0.0
- * @deprecated
- */
- export var getApplySemigroup =
- /*#__PURE__*/ getApplySemigroup_(Apply);
- /**
- * Use [`getApplicativeMonoid`](./Applicative.ts.html#getapplicativemonoid) instead.
- *
- * @category zone of death
- * @since 2.0.0
- * @deprecated
- */
- export var getApplyMonoid =
- /*#__PURE__*/ getApplicativeMonoid(Applicative);
- /**
- * Use [`getApplySemigroup`](./Apply.ts.html#getapplysemigroup) instead.
- *
- * @category zone of death
- * @since 2.0.0
- * @deprecated
- */
- export var getValidationSemigroup = function (SE, SA) {
- return getApplySemigroup_(getApplicativeValidation(SE))(SA);
- };
- /**
- * Use [`getApplicativeMonoid`](./Applicative.ts.html#getapplicativemonoid) instead.
- *
- * @category zone of death
- * @since 2.0.0
- * @deprecated
- */
- export var getValidationMonoid = function (SE, MA) {
- return getApplicativeMonoid(getApplicativeValidation(SE))(MA);
- };
- /**
- * Use [`getApplicativeValidation`](#getapplicativevalidation) and [`getAltValidation`](#getaltvalidation) instead.
- *
- * @category zone of death
- * @since 2.0.0
- * @deprecated
- */
- export function getValidation(SE) {
- var ap = getApplicativeValidation(SE).ap;
- var alt = getAltValidation(SE).alt;
- return {
- URI: URI,
- _E: undefined,
- map: _map,
- of: of,
- chain: _chain,
- bimap: _bimap,
- mapLeft: _mapLeft,
- reduce: _reduce,
- foldMap: _foldMap,
- reduceRight: _reduceRight,
- extend: _extend,
- traverse: _traverse,
- sequence: sequence,
- chainRec: _chainRec,
- throwError: throwError,
- ap: ap,
- alt: alt
- };
- }
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