@jsoldi/hkt/dist/classes/foldable.d.ts

Higher kinded types for typescript and a few utility monads.

import { IFoldBase, IFold } from "./fold.js";
import { IFunctorBase } from "./functor.js";
import { $, $I, $B2, $Q2 } from "../core/hkt.js";
import { IMonadBase, ITrivial } from "./monad.js";
import { TypeClassArg } from "./utilities.js";
/** The minimal definition of a foldable. */
export interface IFoldableBase<F> extends IFunctorBase<F> {
    /** Folds the values of `fa` using the given function and initial value. */
    foldl<A, B>(f: (b: B, a: A) => B): (b: B) => (fa: $<F, A>) => B;
}
/** The foldable interface, where `scalar` is the trivial (identity) monad. */
export interface IFoldable<F> extends IFoldableBase<F>, IFold<F, $I> {
    /** The trivial (identity) monad. */
    readonly scalar: ITrivial;
    /** Lifts a fold over the given monad. */
    liftFoldOver<M>(m: IMonadBase<M>): IFold<$B2<F, M>, M>;
    /** Lifts a fold under the given monad. */
    liftFoldUnder<M>(m: IMonadBase<M>): IFold<$Q2<F, M>, M>;
    /** Nests a fold within another fold. */
    nestFold<M, N>(m: IFoldBase<M, N>): IFold<$B2<F, M>, N>;
}
declare const is_foldable: unique symbol;
/** Creates an `IFoldable` from an `IFoldableBase`. */
export declare function foldable<F>(base: TypeClassArg<IFoldableBase<F>, IFoldable<F>, typeof is_foldable>): IFoldable<F>;
export {};
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