/**
 * ```ts
 * interface Task<A> {
 *   (): Promise<A>
 * }
 * ```
 *
 * `Task<A>` represents an asynchronous computation that yields a value of type `A` and **never fails**.
 * If you want to represent an asynchronous computation that may fail, please see `TaskEither`.
 *
 * @since 2.0.0
 */
import { getApplicativeMonoid } from './Applicative';
import { apFirst as apFirst_, apS as apS_, apSecond as apSecond_, getApplySemigroup as getApplySemigroup_ } from './Apply';
import * as chainable from './Chain';
import { fromIOK as fromIOK_, tapIO as tapIO_ } from './FromIO';
import { dual, identity, pipe } from './function';
import { as as as_, asUnit as asUnit_, bindTo as bindTo_, flap as flap_, let as let__ } from './Functor';
import * as _ from './internal';
// -------------------------------------------------------------------------------------
// conversions
// -------------------------------------------------------------------------------------
/**
 * @category conversions
 * @since 2.0.0
 */
export var fromIO = function (ma) { return function () { return Promise.resolve().then(ma); }; };
// -------------------------------------------------------------------------------------
// combinators
// -------------------------------------------------------------------------------------
/**
 * Creates a task that will complete after a time delay
 *
 * @example
 * import { sequenceT } from 'fp-ts/Apply'
 * import * as T from 'fp-ts/Task'
 * import { takeRight } from 'fp-ts/Array'
 *
 * async function test() {
 *   const log: Array<string> = []
 *   const append = (message: string): T.Task<void> =>
 *     T.fromIO(() => {
 *       log.push(message)
 *     })
 *   const fa = append('a')
 *   const fb = T.delay(20)(append('b'))
 *   const fc = T.delay(10)(append('c'))
 *   const fd = append('d')
 *   await sequenceT(T.ApplyPar)(fa, fb, fc, fd)()
 *   assert.deepStrictEqual(takeRight(2)(log), ['c', 'b'])
 * }
 *
 * test()
 *
 * @since 2.0.0
 */
export function delay(millis) {
    return function (ma) { return function () {
        return new Promise(function (resolve) {
            setTimeout(function () {
                Promise.resolve().then(ma).then(resolve);
            }, millis);
        });
    }; };
}
var _map = function (fa, f) { return pipe(fa, map(f)); };
var _apPar = function (fab, fa) { return pipe(fab, ap(fa)); };
var _apSeq = function (fab, fa) { return flatMap(fab, function (f) { return pipe(fa, map(f)); }); };
/**
 * `map` can be used to turn functions `(a: A) => B` into functions `(fa: F<A>) => F<B>` whose argument and return types
 * use the type constructor `F` to represent some computational context.
 *
 * @category mapping
 * @since 2.0.0
 */
export var map = function (f) { return function (fa) { return function () {
    return Promise.resolve().then(fa).then(f);
}; }; };
/**
 * @since 2.0.0
 */
export var ap = function (fa) { return function (fab) { return function () {
    return Promise.all([Promise.resolve().then(fab), Promise.resolve().then(fa)]).then(function (_a) {
        var f = _a[0], a = _a[1];
        return f(a);
    });
}; }; };
/**
 * @category constructors
 * @since 2.0.0
 */
export var of = function (a) { return function () { return Promise.resolve(a); }; };
/**
 * @category sequencing
 * @since 2.14.0
 */
export var flatMap = /*#__PURE__*/ dual(2, function (ma, f) {
    return function () {
        return Promise.resolve()
            .then(ma)
            .then(function (a) { return f(a)(); });
    };
});
/**
 * @category sequencing
 * @since 2.0.0
 */
export var flatten = /*#__PURE__*/ flatMap(identity);
/**
 * @category type lambdas
 * @since 2.0.0
 */
export var URI = 'Task';
/**
 * Monoid returning the first completed task.
 *
 * Note: uses `Promise.race` internally.
 *
 * @example
 * import * as T from 'fp-ts/Task'
 *
 * async function test() {
 *   const S = T.getRaceMonoid<string>()
 *   const fa = T.delay(20)(T.of('a'))
 *   const fb = T.delay(10)(T.of('b'))
 *   assert.deepStrictEqual(await S.concat(fa, fb)(), 'b')
 * }
 *
 * test()
 *
 * @category instances
 * @since 2.0.0
 */
export function getRaceMonoid() {
    return {
        concat: function (x, y) { return function () { return Promise.race([Promise.resolve().then(x), Promise.resolve().then(y)]); }; },
        empty: never
    };
}
/**
 * @category instances
 * @since 2.7.0
 */
export var Functor = {
    URI: URI,
    map: _map
};
/**
 * Maps the value to the specified constant value.
 *
 * @category mapping
 * @since 2.16.0
 */
export var as = dual(2, as_(Functor));
/**
 * Maps the value to the void constant value.
 *
 * @category mapping
 * @since 2.16.0
 */
export var asUnit = asUnit_(Functor);
/**
 * @category mapping
 * @since 2.10.0
 */
export var flap = /*#__PURE__*/ flap_(Functor);
/**
 * @category instances
 * @since 2.10.0
 */
export var Pointed = {
    URI: URI,
    of: of
};
/**
 * Runs computations in parallel.
 *
 * @category instances
 * @since 2.10.0
 */
export var ApplyPar = {
    URI: URI,
    map: _map,
    ap: _apPar
};
/**
 * Combine two effectful actions, keeping only the result of the first.
 *
 * @since 2.0.0
 */
export var apFirst = /*#__PURE__*/ apFirst_(ApplyPar);
/**
 * Combine two effectful actions, keeping only the result of the second.
 *
 * @since 2.0.0
 */
export var apSecond = /*#__PURE__*/ apSecond_(ApplyPar);
/**
 * Runs computations in parallel.
 *
 * @category instances
 * @since 2.7.0
 */
export var ApplicativePar = {
    URI: URI,
    map: _map,
    ap: _apPar,
    of: of
};
/**
 * Runs computations sequentially.
 *
 * @category instances
 * @since 2.10.0
 */
export var ApplySeq = {
    URI: URI,
    map: _map,
    ap: _apSeq
};
/**
 * Runs computations sequentially.
 *
 * @category instances
 * @since 2.7.0
 */
export var ApplicativeSeq = {
    URI: URI,
    map: _map,
    ap: _apSeq,
    of: of
};
/**
 * @category instances
 * @since 2.10.0
 */
export var Chain = {
    URI: URI,
    map: _map,
    ap: _apPar,
    chain: flatMap
};
/**
 * @category instances
 * @since 2.10.0
 */
export var Monad = {
    URI: URI,
    map: _map,
    of: of,
    ap: _apPar,
    chain: flatMap
};
/**
 * @category instances
 * @since 2.10.0
 */
export var MonadIO = {
    URI: URI,
    map: _map,
    of: of,
    ap: _apPar,
    chain: flatMap,
    fromIO: fromIO
};
/**
 * @category zone of death
 * @since 2.7.0
 * @deprecated
 */
export var fromTask = identity;
/**
 * @category instances
 * @since 2.10.0
 */
export var MonadTask = {
    URI: URI,
    map: _map,
    of: of,
    ap: _apPar,
    chain: flatMap,
    fromIO: fromIO,
    fromTask: fromTask
};
/**
 * @category instances
 * @since 2.10.0
 */
export var FromIO = {
    URI: URI,
    fromIO: fromIO
};
/** @internal */
var _FlatMap = {
    flatMap: flatMap
};
/** @internal */
var _FromIO = {
    fromIO: FromIO.fromIO
};
/**
 * @category sequencing
 * @since 2.16.0
 */
export var flatMapIO = _.flatMapIO(_FromIO, _FlatMap);
/**
 * 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 combinators
 * @since 2.15.0
 */
export var tap = /*#__PURE__*/ dual(2, chainable.tap(Chain));
/**
 * Composes computations in sequence, using the return value of one computation to determine the next computation and
 * keeping only the result of the first.
 *
 * @example
 * import { pipe } from 'fp-ts/function'
 * import * as T from 'fp-ts/Task'
 * import * as Console from 'fp-ts/Console'
 *
 * // Will produce `Hello, fp-ts` to the stdout
 * const effect = pipe(
 *   T.of('fp-ts'),
 *   T.tapIO((value) => Console.log(`Hello, ${value}`)),
 * )
 *
 * async function test() {
 *   assert.deepStrictEqual(await effect(), 'fp-ts')
 * }
 *
 * test()
 *
 * @category combinators
 * @since 2.16.0
 */
export var tapIO = /*#__PURE__*/ dual(2, tapIO_(FromIO, Chain));
/**
 * @category lifting
 * @since 2.4.0
 */
export var fromIOK = 
/*#__PURE__*/ fromIOK_(FromIO);
/**
 * Alias of `flatMapIO`.
 *
 * @category legacy
 * @since 2.4.0
 */
export var chainIOK = flatMapIO;
/**
 * Alias of `tapIO`.
 *
 * @category legacy
 * @since 2.10.0
 */
export var chainFirstIOK = tapIO;
/**
 * @category instances
 * @since 2.10.0
 */
export var FromTask = {
    URI: URI,
    fromIO: fromIO,
    fromTask: fromTask
};
// -------------------------------------------------------------------------------------
// utils
// -------------------------------------------------------------------------------------
/**
 * A `Task` that never completes.
 *
 * @since 2.0.0
 */
export var never = function () { return new Promise(function (_) { return undefined; }); };
// -------------------------------------------------------------------------------------
// 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__*/ chainable.bind(Chain);
/**
 * @category do notation
 * @since 2.8.0
 */
export var apS = /*#__PURE__*/ apS_(ApplyPar);
/**
 * @since 2.11.0
 */
export var ApT = /*#__PURE__*/ of(_.emptyReadonlyArray);
// -------------------------------------------------------------------------------------
// array utils
// -------------------------------------------------------------------------------------
/**
 * Equivalent to `ReadonlyNonEmptyArray#traverseWithIndex(ApplicativePar)`.
 *
 * @category traversing
 * @since 2.11.0
 */
export var traverseReadonlyNonEmptyArrayWithIndex = function (f) {
    return function (as) {
        return function () {
            return Promise.all(as.map(function (a, i) { return Promise.resolve().then(function () { return f(i, a)(); }); }));
        };
    };
};
/**
 * Equivalent to `ReadonlyArray#traverseWithIndex(ApplicativePar)`.
 *
 * @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 `ReadonlyNonEmptyArray#traverseWithIndex(ApplicativeSeq)`.
 *
 * @category traversing
 * @since 2.11.0
 */
export var traverseReadonlyNonEmptyArrayWithIndexSeq = function (f) {
    return function (as) {
        return function () {
            return _.tail(as).reduce(function (acc, a, i) {
                return acc.then(function (bs) {
                    return Promise.resolve()
                        .then(f(i + 1, a))
                        .then(function (b) {
                        bs.push(b);
                        return bs;
                    });
                });
            }, Promise.resolve()
                .then(f(0, _.head(as)))
                .then(_.singleton));
        };
    };
};
/**
 * Equivalent to `ReadonlyArray#traverseWithIndex(ApplicativeSeq)`.
 *
 * @category traversing
 * @since 2.11.0
 */
export var traverseReadonlyArrayWithIndexSeq = function (f) {
    var g = traverseReadonlyNonEmptyArrayWithIndexSeq(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);
/**
 * Equivalent to `ReadonlyArray#traverseWithIndex(ApplicativeSeq)`.
 *
 * @category traversing
 * @since 2.9.0
 */
export var traverseSeqArrayWithIndex = traverseReadonlyArrayWithIndexSeq;
/**
 * Equivalent to `ReadonlyArray#traverse(ApplicativeSeq)`.
 *
 * @category traversing
 * @since 2.9.0
 */
export var traverseSeqArray = function (f) {
    return traverseReadonlyArrayWithIndexSeq(function (_, a) { return f(a); });
};
/**
 * Equivalent to `ReadonlyArray#sequence(ApplicativeSeq)`.
 *
 * @category traversing
 * @since 2.9.0
 */
export var sequenceSeqArray = 
/*#__PURE__*/ traverseSeqArray(identity);
// -------------------------------------------------------------------------------------
// legacy
// -------------------------------------------------------------------------------------
/**
 * Alias of `flatMap`.
 *
 * @category legacy
 * @since 2.0.0
 */
export var chain = flatMap;
/**
 * Alias of `tap`.
 *
 * @category legacy
 * @since 2.0.0
 */
export var chainFirst = tap;
// -------------------------------------------------------------------------------------
// deprecated
// -------------------------------------------------------------------------------------
/**
 * This instance is deprecated, use small, specific instances instead.
 * For example if a function needs a `Functor` instance, pass `T.Functor` instead of `T.task`
 * (where `T` is from `import T from 'fp-ts/Task'`)
 *
 * @category zone of death
 * @since 2.0.0
 * @deprecated
 */
export var task = {
    URI: URI,
    map: _map,
    of: of,
    ap: _apPar,
    chain: flatMap,
    fromIO: fromIO,
    fromTask: fromTask
};
/**
 * This instance is deprecated, use small, specific instances instead.
 * For example if a function needs a `Functor` instance, pass `T.Functor` instead of `T.taskSeq`
 * (where `T` is from `import T from 'fp-ts/Task'`)
 *
 * @category zone of death
 * @since 2.0.0
 * @deprecated
 */
export var taskSeq = {
    URI: URI,
    map: _map,
    of: of,
    ap: _apSeq,
    chain: flatMap,
    fromIO: fromIO,
    fromTask: fromTask
};
/**
 * Use [`getApplySemigroup`](./Apply.ts.html#getapplysemigroup) instead.
 *
 * @category zone of death
 * @since 2.0.0
 * @deprecated
 */
export var getSemigroup = /*#__PURE__*/ getApplySemigroup_(ApplySeq);
/**
 * Use [`getApplicativeMonoid`](./Applicative.ts.html#getapplicativemonoid) instead.
 *
 * Lift a monoid into 'Task', the inner values are concatenated using the provided `Monoid`.
 *
 * @category zone of death
 * @since 2.0.0
 * @deprecated
 */
export var getMonoid = /*#__PURE__*/ getApplicativeMonoid(ApplicativeSeq);