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- /**
- * The `Reader` monad (also called the Environment monad). Represents a computation, which can read values from a shared environment,
- * pass values from function to function, and execute sub-computations in a modified environment.
- * Using `Reader` monad for such computations is often clearer and easier than using the `State` monad.
- *
- * In this example the `Reader` monad provides access to variable bindings. `Bindings` are a map of `number` variables.
- * The variable count contains number of variables in the bindings. You can see how to run a `Reader` monad and retrieve
- * data from it, how to access the `Reader` data with `ask` and `asks`.
- *
- * @example
- * import { pipe } from 'fp-ts/function'
- * import * as O from 'fp-ts/Option'
- * import * as R from 'fp-ts/Reader'
- * import * as RR from 'fp-ts/ReadonlyRecord'
- *
- * interface Bindings extends RR.ReadonlyRecord<string, number> {}
- *
- * // The Reader monad, which implements this complicated check.
- * const isCountCorrect: R.Reader<Bindings, boolean> = pipe(
- * R.Do,
- * R.bind('count', () => R.asks(lookupVar('count'))),
- * R.bind('bindings', () => R.ask()),
- * R.map(({ count, bindings }) => count === RR.size(bindings))
- * )
- *
- * // The selector function to use with 'asks'.
- * // Returns value of the variable with specified name.
- * const lookupVar = (name: string) => (bindings: Bindings): number =>
- * pipe(
- * bindings,
- * RR.lookup(name),
- * O.getOrElse(() => 0)
- * )
- *
- * const sampleBindings: Bindings = { count: 3, a: 1, b: 2 }
- *
- * assert.deepStrictEqual(isCountCorrect(sampleBindings), true)
- *
- * @since 2.0.0
- */
- import { getApplicativeMonoid } from './Applicative';
- import { apFirst as apFirst_, apS as apS_, apSecond as apSecond_, getApplySemigroup } from './Apply';
- import { bind as bind_, chainFirst as chainFirst_ } from './Chain';
- import * as E from './Either';
- import { constant, flow, identity, pipe } from './function';
- import { let as let__, bindTo as bindTo_, flap as flap_ } from './Functor';
- import * as _ from './internal';
- // -------------------------------------------------------------------------------------
- // constructors
- // -------------------------------------------------------------------------------------
- /**
- * Reads the current context
- *
- * @category constructors
- * @since 2.0.0
- */
- export var ask = function () { return identity; };
- /**
- * Projects a value from the global context in a Reader
- *
- * @category constructors
- * @since 2.0.0
- */
- export var asks = identity;
- // -------------------------------------------------------------------------------------
- // combinators
- // -------------------------------------------------------------------------------------
- /**
- * Changes the value of the local context during the execution of the action `ma` (similar to `Contravariant`'s
- * `contramap`).
- *
- * @example
- * import { pipe } from 'fp-ts/function'
- * import * as R from 'fp-ts/Reader'
- * import * as string from 'fp-ts/string'
- *
- * const calculateContentLen: R.Reader<string, number> = pipe(
- * R.Do,
- * R.bind('content', () => R.ask<string>()),
- * R.map(({ content }) => string.size(content))
- * )
- *
- * // Calls calculateContentLen after adding a prefix to the Reader content.
- * const calculateModifiedContentLen: R.Reader<string, number> = pipe(
- * calculateContentLen,
- * R.local((s) => 'Prefix ' + s)
- * )
- *
- * const s = '12345'
- *
- * assert.deepStrictEqual(
- * "Modified 's' length: " + calculateModifiedContentLen(s) + '\n' + "Original 's' length: " + calculateContentLen(s),
- * "Modified 's' length: 12\nOriginal 's' length: 5"
- * )
- *
- * @since 2.0.0
- */
- export var local = function (f) { return function (ma) { return function (r2) {
- return ma(f(r2));
- }; }; };
- /**
- * Less strict version of [`asksReader`](#asksreader).
- *
- * The `W` suffix (short for **W**idening) means that the environment types will be merged.
- *
- * @category constructors
- * @since 2.11.0
- */
- export var asksReaderW = function (f) {
- return function (r) {
- return f(r)(r);
- };
- };
- /**
- * Effectfully accesses the environment.
- *
- * @category constructors
- * @since 2.11.0
- */
- export var asksReader = asksReaderW;
- /* istanbul ignore next */
- var _map = function (fa, f) { return pipe(fa, map(f)); };
- /* istanbul ignore next */
- var _ap = function (fab, fa) { return pipe(fab, ap(fa)); };
- /* istanbul ignore next */
- var _chain = function (ma, f) { return pipe(ma, chain(f)); };
- var _compose = function (bc, ab) { return pipe(bc, compose(ab)); };
- var _promap = function (fea, f, g) { return pipe(fea, promap(f, g)); };
- /**
- * `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 (r) { return f(fa(r)); }; }; };
- /**
- * Less strict version of [`ap`](#ap).
- *
- * The `W` suffix (short for **W**idening) means that the environment types will be merged.
- *
- * @since 2.8.0
- */
- export var apW = function (fa) { return function (fab) { return function (r) {
- return fab(r)(fa(r));
- }; }; };
- /**
- * @since 2.0.0
- */
- export var ap = apW;
- /**
- * @category constructors
- * @since 2.0.0
- */
- export var of = constant;
- /**
- * Less strict version of [`chain`](#chain).
- *
- * The `W` suffix (short for **W**idening) means that the environment types will be merged.
- *
- * @category sequencing
- * @since 2.6.0
- */
- export var chainW = function (f) { return function (fa) { return function (r) {
- return f(fa(r))(r);
- }; }; };
- /**
- * 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;
- /**
- * Less strict version of [`flatten`](#flatten).
- *
- * The `W` suffix (short for **W**idening) means that the environment types will be merged.
- *
- * @category sequencing
- * @since 2.11.0
- */
- export var flattenW =
- /*#__PURE__*/ chainW(identity);
- /**
- * @category sequencing
- * @since 2.0.0
- */
- export var flatten = flattenW;
- /**
- * @since 2.0.0
- */
- export var compose = function (ab) { return function (bc) { return flow(ab, bc); }; };
- /**
- * @since 2.0.0
- */
- export var promap = function (f, g) { return function (fea) { return function (a) {
- return g(fea(f(a)));
- }; }; };
- /**
- * @category constructors
- * @since 2.0.0
- */
- export var id = function () { return identity; };
- /**
- * @since 2.10.0
- */
- export var first = function (pab) {
- return function (_a) {
- var a = _a[0], c = _a[1];
- return [pab(a), c];
- };
- };
- /**
- * @since 2.10.0
- */
- export var second = function (pbc) {
- return function (_a) {
- var a = _a[0], b = _a[1];
- return [a, pbc(b)];
- };
- };
- /**
- * @since 2.10.0
- */
- export var left = function (pab) { return E.fold(function (a) { return _.left(pab(a)); }, E.right); };
- /**
- * @since 2.10.0
- */
- export var right = function (pbc) { return E.fold(E.left, function (b) { return _.right(pbc(b)); }); };
- /**
- * @category type lambdas
- * @since 2.0.0
- */
- export var URI = 'Reader';
- /**
- * @category instances
- * @since 2.7.0
- */
- export var Functor = {
- URI: URI,
- map: _map
- };
- /**
- * @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
- };
- /**
- * @category instances
- * @since 2.10.0
- */
- export var Apply = {
- URI: URI,
- map: _map,
- ap: _ap
- };
- /**
- * 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 environment 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 environment types will be merged.
- *
- * @since 2.12.0
- */
- export var apSecondW = apSecond;
- /**
- * @category instances
- * @since 2.7.0
- */
- export var Applicative = {
- URI: URI,
- map: _map,
- ap: _ap,
- of: of
- };
- /**
- * @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,
- of: of,
- ap: _ap,
- chain: _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.
- *
- * @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 environment types will be merged.
- *
- * @category sequencing
- * @since 2.11.0
- */
- export var chainFirstW = chainFirst;
- /**
- * @category instances
- * @since 2.7.0
- */
- export var Profunctor = {
- URI: URI,
- map: _map,
- promap: _promap
- };
- /**
- * @category instances
- * @since 2.7.0
- */
- export var Category = {
- URI: URI,
- compose: _compose,
- id: id
- };
- /**
- * @category instances
- * @since 2.8.3
- */
- export var Strong = {
- URI: URI,
- map: _map,
- promap: _promap,
- first: first,
- second: second
- };
- /**
- * @category instances
- * @since 2.8.3
- */
- export var Choice = {
- URI: URI,
- map: _map,
- promap: _promap,
- left: left,
- right: right
- };
- // -------------------------------------------------------------------------------------
- // do notation
- // -------------------------------------------------------------------------------------
- /**
- * @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 environment types will be merged.
- *
- * @category do notation
- * @since 2.8.0
- */
- export var bindW = bind;
- /**
- * @category do notation
- * @since 2.9.0
- */
- export var Do = /*#__PURE__*/ of(_.emptyRecord);
- /**
- * @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 environment 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) {
- return function (r) {
- var out = [f(0, _.head(as))(r)];
- for (var i = 1; i < as.length; i++) {
- out.push(f(i, as[i])(r));
- }
- return 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);
- // -------------------------------------------------------------------------------------
- // deprecated
- // -------------------------------------------------------------------------------------
- /**
- * This instance is deprecated, use small, specific instances instead.
- * For example if a function needs a `Functor` instance, pass `R.Functor` instead of `R.reader`
- * (where `R` is from `import R from 'fp-ts/Reader'`)
- *
- * @category zone of death
- * @since 2.0.0
- * @deprecated
- */
- export var reader = {
- URI: URI,
- map: _map,
- of: of,
- ap: _ap,
- chain: _chain,
- promap: _promap,
- compose: _compose,
- id: id,
- first: first,
- second: second,
- left: left,
- right: right
- };
- /**
- * Use [`getApplySemigroup`](./Apply.ts.html#getapplysemigroup) instead.
- *
- * @category zone of death
- * @since 2.0.0
- * @deprecated
- */
- export var getSemigroup = /*#__PURE__*/ getApplySemigroup(Apply);
- /**
- * Use [`getApplicativeMonoid`](./Applicative.ts.html#getapplicativemonoid) instead.
- *
- * @category zone of death
- * @since 2.0.0
- * @deprecated
- */
- export var getMonoid = /*#__PURE__*/ getApplicativeMonoid(Applicative);
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