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Kleisli.ts
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Kleisli.ts
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/**
* **This module is experimental**
*
* Experimental features are published in order to get early feedback from the community, see these tracking
* [issues](https://github.com/gcanti/io-ts/issues?q=label%3Av2.2+) for further discussions and enhancements.
*
* A feature tagged as _Experimental_ is in a high state of flux, you're at risk of it changing without notice.
*
* @since 2.2.7
*/
import { Alt2C } from 'fp-ts/lib/Alt'
import { Applicative2C } from 'fp-ts/lib/Applicative'
import { Apply2C } from 'fp-ts/lib/Apply'
import { Bifunctor2 } from 'fp-ts/lib/Bifunctor'
import * as E from 'fp-ts/lib/Either'
import { Lazy, Refinement } from 'fp-ts/lib/function'
import { Functor2C } from 'fp-ts/lib/Functor'
import { Kind2, URIS2 } from 'fp-ts/lib/HKT'
import { Monad2C } from 'fp-ts/lib/Monad'
import { MonadThrow2C } from 'fp-ts/lib/MonadThrow'
import * as G from './Guard'
import * as S from './Schemable'
// -------------------------------------------------------------------------------------
// model
// -------------------------------------------------------------------------------------
/**
* @category model
* @since 2.2.7
*/
export interface Kleisli<M extends URIS2, I, E, A> {
readonly decode: (i: I) => Kind2<M, E, A>
}
// -------------------------------------------------------------------------------------
// constructors
// -------------------------------------------------------------------------------------
/**
* @category constructors
* @since 2.2.7
*/
export function fromRefinement<M extends URIS2, E>(
M: MonadThrow2C<M, E>
): <I, A extends I>(refinement: Refinement<I, A>, onError: (i: I) => E) => Kleisli<M, I, E, A> {
return (refinement, onError) => ({
decode: (i) => (refinement(i) ? M.of(i) : M.throwError(onError(i)))
})
}
/**
* @category constructors
* @since 2.2.7
*/
export function literal<M extends URIS2, E>(
M: MonadThrow2C<M, E>
): <I>(
onError: (i: I, values: readonly [S.Literal, ...ReadonlyArray<S.Literal>]) => E
) => <A extends readonly [L, ...ReadonlyArray<L>], L extends S.Literal = S.Literal>(
...values: A
) => Kleisli<M, I, E, A[number]> {
return (onError) =>
<A extends readonly [S.Literal, ...Array<S.Literal>]>(...values: A) => ({
decode: (i) => (G.literal(...values).is(i) ? M.of<A[number]>(i) : M.throwError(onError(i, values)))
})
}
// -------------------------------------------------------------------------------------
// combinators
// -------------------------------------------------------------------------------------
/**
* @category combinators
* @since 2.2.7
*/
export function mapLeftWithInput<M extends URIS2>(
M: Bifunctor2<M>
): <I, E>(f: (i: I, e: E) => E) => <A>(decoder: Kleisli<M, I, E, A>) => Kleisli<M, I, E, A> {
return (f) => (decoder) => ({
decode: (i) => M.mapLeft(decoder.decode(i), (e) => f(i, e))
})
}
/**
* @category combinators
* @since 2.2.7
*/
export function refine<M extends URIS2, E>(
M: MonadThrow2C<M, E> & Bifunctor2<M>
): <A, B extends A>(
refinement: (a: A) => a is B,
onError: (a: A) => E
) => <I>(from: Kleisli<M, I, E, A>) => Kleisli<M, I, E, B> {
return (refinement, onError) => (from) => compose(M)(fromRefinement(M)(refinement, onError))(from)
}
/**
* @category combinators
* @since 2.2.7
*/
export function parse<M extends URIS2, E>(
M: Monad2C<M, E>
): <A, B>(decode: (a: A) => Kind2<M, E, B>) => <I>(from: Kleisli<M, I, E, A>) => Kleisli<M, I, E, B> {
return (decode) => (from) => compose(M)({ decode })(from)
}
/**
* @category combinators
* @since 2.2.7
*/
export function nullable<M extends URIS2, E>(
M: Applicative2C<M, E> & Bifunctor2<M>
): <I>(onError: (i: I, e: E) => E) => <A>(or: Kleisli<M, I, E, A>) => Kleisli<M, null | I, E, null | A> {
return <I>(onError: (i: I, e: E) => E) =>
<A>(or: Kleisli<M, I, E, A>): Kleisli<M, null | I, E, null | A> => ({
decode: (i) =>
i === null
? M.of<null | A>(null)
: M.bimap(
or.decode(i),
(e) => onError(i, e),
(a): A | null => a
)
})
}
/**
* @category combinators
* @since 2.2.15
*/
export function fromStruct<M extends URIS2, E>(
M: Applicative2C<M, E> & Bifunctor2<M>
): (
onPropertyError: (key: string, e: E) => E
) => <P extends Record<string, Kleisli<M, any, E, any>>>(
properties: P
) => Kleisli<M, { [K in keyof P]: InputOf<M, P[K]> }, E, { [K in keyof P]: TypeOf<M, P[K]> }> {
const traverse = traverseRecordWithIndex(M)
return (onPropertyError) => (properties) => ({
decode: (i) =>
traverse(properties as Record<string, Kleisli<M, unknown, E, unknown>>, (key, decoder) =>
M.mapLeft(decoder.decode(i[key]), (e) => onPropertyError(key, e))
) as any
})
}
/**
* Use `fromStruct` instead.
*
* @category combinators
* @since 2.2.7
* @deprecated
*/
export const fromType = fromStruct
/**
* @category combinators
* @since 2.2.7
*/
export function fromPartial<M extends URIS2, E>(
M: Applicative2C<M, E> & Bifunctor2<M>
): (
onPropertyError: (key: string, e: E) => E
) => <P extends Record<string, Kleisli<M, any, E, any>>>(
properties: P
) => Kleisli<M, Partial<{ [K in keyof P]: InputOf<M, P[K]> }>, E, Partial<{ [K in keyof P]: TypeOf<M, P[K]> }>> {
const traverse = traverseRecordWithIndex(M)
const undefinedProperty = M.of<E.Either<void, unknown>>(E.right(undefined))
const skipProperty = M.of<E.Either<void, unknown>>(E.left(undefined))
return (onPropertyError) => (properties) => ({
decode: (i) =>
M.map(
traverse(properties as Record<string, Kleisli<M, unknown, E, unknown>>, (key, decoder) => {
const ikey = i[key]
if (ikey === undefined) {
return key in i
? // don't strip undefined properties
undefinedProperty
: // don't add missing properties
skipProperty
}
return M.bimap(
decoder.decode(ikey),
(e) => onPropertyError(key, e),
(a) => E.right<void, unknown>(a)
)
}),
compactRecord
) as any
})
}
/**
* @category combinators
* @since 2.2.7
*/
export function fromArray<M extends URIS2, E>(
M: Applicative2C<M, E> & Bifunctor2<M>
): (onItemError: (index: number, e: E) => E) => <I, A>(item: Kleisli<M, I, E, A>) => Kleisli<M, Array<I>, E, Array<A>> {
const traverse = traverseArrayWithIndex(M)
return (onItemError) => (item) => ({
decode: (is) => traverse(is, (index, i) => M.mapLeft(item.decode(i), (e) => onItemError(index, e)))
})
}
/**
* @category combinators
* @since 2.2.7
*/
export function fromRecord<M extends URIS2, E>(
M: Applicative2C<M, E> & Bifunctor2<M>
): (
onKeyError: (key: string, e: E) => E
) => <I, A>(codomain: Kleisli<M, I, E, A>) => Kleisli<M, Record<string, I>, E, Record<string, A>> {
const traverse = traverseRecordWithIndex(M)
return (onKeyError) => (codomain) => ({
decode: (ir) => traverse(ir, (key, i) => M.mapLeft(codomain.decode(i), (e) => onKeyError(key, e)))
})
}
/**
* @category combinators
* @since 2.2.7
*/
export function fromTuple<M extends URIS2, E>(
M: Applicative2C<M, E> & Bifunctor2<M>
): (
onIndexError: (index: number, e: E) => E
) => <C extends ReadonlyArray<Kleisli<M, any, E, any>>>(
...components: C
) => Kleisli<M, { [K in keyof C]: InputOf<M, C[K]> }, E, { [K in keyof C]: TypeOf<M, C[K]> }> {
const traverse = traverseArrayWithIndex(M)
return (onIndexError) =>
(...components) => ({
decode: (is) =>
traverse(components as unknown as Array<Kleisli<M, unknown, E, unknown>>, (index, decoder) =>
M.mapLeft(decoder.decode(is[index]), (e) => onIndexError(index, e))
) as any
})
}
/**
* @category combinators
* @since 2.2.7
*/
export function union<M extends URIS2, E>(
M: Alt2C<M, E> & Bifunctor2<M>
): (
onMemberError: (index: number, e: E) => E
) => <MS extends readonly [Kleisli<M, any, E, any>, ...Array<Kleisli<M, any, E, any>>]>(
...members: MS
) => Kleisli<M, InputOf<M, MS[keyof MS]>, E, TypeOf<M, MS[keyof MS]>> {
return (onMemberError) =>
<MS extends readonly [Kleisli<M, any, E, any>, ...Array<Kleisli<M, any, E, any>>]>(...members: MS) => ({
decode: (i) => {
let out: Kind2<M, E, TypeOf<M, MS[keyof MS]>> = M.mapLeft(members[0].decode(i), (e) => onMemberError(0, e))
for (let index = 1; index < members.length; index++) {
out = M.alt(out, () => M.mapLeft(members[index].decode(i), (e) => onMemberError(index, e)))
}
return out
}
})
}
/**
* @category combinators
* @since 2.2.7
*/
export function intersect<M extends URIS2, E>(
M: Apply2C<M, E>
): <IB, B>(right: Kleisli<M, IB, E, B>) => <IA, A>(left: Kleisli<M, IA, E, A>) => Kleisli<M, IA & IB, E, A & B> {
return <IB, B>(right: Kleisli<M, IB, E, B>) =>
<IA, A>(left: Kleisli<M, IA, E, A>): Kleisli<M, IA & IB, E, A & B> => ({
decode: (i) =>
M.ap(
M.map(left.decode(i), (a: A) => (b: B) => S.intersect_(a, b)),
right.decode(i)
)
})
}
/**
* @category combinators
* @since 2.2.7
*/
export function fromSum<M extends URIS2, E>(
M: MonadThrow2C<M, E>
): (
onTagError: (tag: string, value: unknown, tags: ReadonlyArray<string>) => E
) => <T extends string>(
tag: T
) => <MS extends Record<string, Kleisli<M, any, E, any>>>(
members: MS
) => Kleisli<M, InputOf<M, MS[keyof MS]>, E, TypeOf<M, MS[keyof MS]>> {
return (onTagError) =>
(tag) =>
<I extends Record<string, unknown>, A>(members: { [K in keyof A]: Kleisli<M, I, E, A[K]> }): Kleisli<
M,
I,
E,
A[keyof A]
> => {
const keys = Object.keys(members)
return {
decode: (ir) => {
const v: any = ir[tag]
if (Object.prototype.hasOwnProperty.call(members, v)) {
return (members as any)[v].decode(ir)
}
return M.throwError(onTagError(tag, v, keys))
}
}
}
}
/**
* @category combinators
* @since 2.2.7
*/
export function lazy<M extends URIS2>(
M: Bifunctor2<M>
): <E>(onError: (id: string, e: E) => E) => <I, A>(id: string, f: () => Kleisli<M, I, E, A>) => Kleisli<M, I, E, A> {
return <E>(onError: (id: string, e: E) => E) =>
<I, A>(id: string, f: () => Kleisli<M, I, E, A>): Kleisli<M, I, E, A> => {
const get = S.memoize<void, Kleisli<M, I, E, A>>(f)
return {
decode: (u) => M.mapLeft(get().decode(u), (e) => onError(id, e))
}
}
}
/**
* @category combinators
* @since 2.2.7
*/
export function compose<M extends URIS2, E>(
M: Monad2C<M, E>
): <A, B>(ab: Kleisli<M, A, E, B>) => <I>(ia: Kleisli<M, I, E, A>) => Kleisli<M, I, E, B> {
return (ab) => (ia) => ({
decode: (i) => M.chain(ia.decode(i), ab.decode)
})
}
/**
* @category combinators
* @since 2.2.8
*/
export function id<M extends URIS2, E>(M: Applicative2C<M, E>): <A>() => Kleisli<M, A, E, A> {
return () => ({
decode: M.of
})
}
/**
* @category combinators
* @since 2.2.7
*/
export function map<F extends URIS2, E>(
F: Functor2C<F, E>
): <A, B>(f: (a: A) => B) => <I>(ia: Kleisli<F, I, E, A>) => Kleisli<F, I, E, B> {
return (f) => (ia) => ({
decode: (i) => F.map(ia.decode(i), f)
})
}
/**
* @category combinators
* @since 2.2.7
*/
export function alt<F extends URIS2, E>(
A: Alt2C<F, E>
): <I, A>(that: Lazy<Kleisli<F, I, E, A>>) => (me: Kleisli<F, I, E, A>) => Kleisli<F, I, E, A> {
return (that) => (me) => ({
decode: (i) => A.alt(me.decode(i), () => that().decode(i))
})
}
// -------------------------------------------------------------------------------------
// utils
// -------------------------------------------------------------------------------------
const traverseArrayWithIndex =
<M extends URIS2, E>(M: Applicative2C<M, E>) =>
<A, B>(as: Array<A>, f: (i: number, a: A) => Kind2<M, E, B>): Kind2<M, E, Array<B>> => {
return as.reduce(
(mbs, a, i) =>
M.ap(
M.map(mbs, (bs) => (b: B) => {
bs.push(b)
return bs
}),
f(i, a)
),
M.of<Array<B>>([])
)
}
const traverseRecordWithIndex =
<M extends URIS2, E>(M: Applicative2C<M, E>) =>
<A, B>(r: Record<string, A>, f: (k: string, a: A) => Kind2<M, E, B>): Kind2<M, E, Record<string, B>> => {
const ks = Object.keys(r)
if (ks.length === 0) {
return M.of({})
}
let fr: Kind2<M, E, Record<string, B>> = M.of({})
for (const key of ks) {
fr = M.ap(
M.map(fr, (r) => (b: B) => {
r[key] = b
return r
}),
f(key, r[key])
)
}
return fr
}
const compactRecord = <A>(r: Record<string, E.Either<void, A>>): Record<string, A> => {
const out: Record<string, A> = {}
for (const k in r) {
const rk = r[k]
if (E.isRight(rk)) {
out[k] = rk.right
}
}
return out
}
// -------------------------------------------------------------------------------------
// utils
// -------------------------------------------------------------------------------------
/**
* @since 2.2.7
*/
export type TypeOf<M extends URIS2, KD> = KD extends Kleisli<M, any, any, infer A> ? A : never
/**
* @since 2.2.7
*/
export type InputOf<M extends URIS2, KD> = KD extends Kleisli<M, infer I, any, any> ? I : never