Covariant overview
Added in v0.24.0
Table of contents
do notation
let
Signature
export declare const let: <F extends TypeLambda>(
F: Covariant<F>
) => {
<N extends string, A extends object, B>(
name: Exclude<N, keyof A>,
f: (a: A) => B
): <R, O, E>(self: Kind<F, R, O, E, A>) => Kind<F, R, O, E, { [K in keyof A | N]: K extends keyof A ? A[K] : B }>
<R, O, E, A extends object, N extends string, B>(
self: Kind<F, R, O, E, A>,
name: Exclude<N, keyof A>,
f: (a: A) => B
): Kind<F, R, O, E, { [K in keyof A | N]: K extends keyof A ? A[K] : B }>
}
Example
import * as covariant from "@effect/typeclass/Covariant"
import type { HKT } from "effect"
import { dual, pipe } from "effect/Function"
interface MyData<A> {
readonly value: A
}
interface MyDataTypeLambda extends HKT.TypeLambda {
readonly type: MyData<this["Target"]>
}
const map: covariant.Covariant<MyDataTypeLambda>["map"] = dual(
2,
<A, B>(self: MyData<A>, f: (a: A) => B): MyData<B> => ({ value: f(self.value) })
)
const Covariant: covariant.Covariant<MyDataTypeLambda> = { imap: covariant.imap<MyDataTypeLambda>(map), map }
const notation = {
Do: { value: {} } as MyData<{}>,
let: covariant.let(Covariant)
}
assert.deepStrictEqual(
pipe(
notation.Do,
notation.let("foo", () => "bar")
),
{ value: { foo: "bar" } }
)
Added in v0.24.0
mapping
as
Signature
export declare const as: <F extends TypeLambda>(
F: Covariant<F>
) => {
<B>(b: B): <R, O, E, _>(self: Kind<F, R, O, E, _>) => Kind<F, R, O, E, B>
<R, O, E, _, B>(self: Kind<F, R, O, E, _>, b: B): Kind<F, R, O, E, B>
}
Added in v0.24.0
asVoid
Signature
export declare const asVoid: <F extends TypeLambda>(
F: Covariant<F>
) => <R, O, E, _>(self: Kind<F, R, O, E, _>) => Kind<F, R, O, E, void>
Added in v0.24.0
flap
Signature
export declare const flap: <F extends TypeLambda>(
F: Covariant<F>
) => {
<R, O, E, A, B>(self: Kind<F, R, O, E, (a: A) => B>): (a: A) => Kind<F, R, O, E, B>
<A, R, O, E, B>(a: A, self: Kind<F, R, O, E, (a: A) => B>): Kind<F, R, O, E, B>
}
Added in v0.24.0
type class
Covariant (interface)
Signature
export interface Covariant<F extends TypeLambda> extends Invariant<F> {
readonly map: {
<A, B>(f: (a: A) => B): <R, O, E>(self: Kind<F, R, O, E, A>) => Kind<F, R, O, E, B>
<R, O, E, A, B>(self: Kind<F, R, O, E, A>, f: (a: A) => B): Kind<F, R, O, E, B>
}
}
Added in v0.24.0
utils
imap
Returns a default imap
implementation.
Signature
export declare const imap: <F extends TypeLambda>(
map: <R, O, E, A, B>(self: Kind<F, R, O, E, A>, f: (a: A) => B) => Kind<F, R, O, E, B>
) => Invariant<F>["imap"]
Added in v0.24.0
mapComposition
Returns a default map
composition.
Signature
export declare const mapComposition: <F extends TypeLambda, G extends TypeLambda>(
F: Covariant<F>,
G: Covariant<G>
) => <FR, FO, FE, GR, GO, GE, A, B>(
self: Kind<F, FR, FO, FE, Kind<G, GR, GO, GE, A>>,
f: (a: A) => B
) => Kind<F, FR, FO, FE, Kind<G, GR, GO, GE, B>>
Added in v0.24.0