An educational pure functional programming library in TypeScript
Add prelude/compose module with pipe, flow, id, constant
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src/prelude/compose.ts
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src/prelude/compose.ts
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// Pure composition utilities for purus-ts prelude layer
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// Identity function
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export const id = <A>(a: A): A => a
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// Constant function
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export const constant = <A>(a: A) => (): A => a
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// Flip curried function arguments
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export const flip = <A, B, C>(f: (a: A) => (b: B) => C) =>
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(b: B) =>
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(a: A): C =>
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f(a)(b)
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// Side effect tap
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export const tap = <A>(f: (a: A) => void) =>
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(a: A): A => {
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f(a)
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return a
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}
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// pipe overloads (at least 6 overloads for type inference)
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export function pipe<A>(a: A): A
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export function pipe<A, B>(a: A, ab: (a: A) => B): B
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export function pipe<A, B, C>(a: A, ab: (a: A) => B, bc: (b: B) => C): C
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export function pipe<A, B, C, D>(
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a: A,
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ab: (a: A) => B,
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bc: (b: B) => C,
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cd: (c: C) => D
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): D
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export function pipe<A, B, C, D, E>(
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a: A,
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ab: (a: A) => B,
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bc: (b: B) => C,
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cd: (c: C) => D,
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de: (d: D) => E
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): E
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export function pipe<A, B, C, D, E, F>(
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a: A,
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ab: (a: A) => B,
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bc: (b: B) => C,
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cd: (c: C) => D,
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de: (d: D) => E,
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ef: (e: E) => F
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): F
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export function pipe(
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a: unknown,
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...fns: Array<(x: unknown) => unknown>
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): unknown {
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return fns.reduce((acc, fn) => fn(acc), a)
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}
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// flow overloads (at least 4)
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export function flow<A, B>(ab: (a: A) => B): (a: A) => B
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export function flow<A, B, C>(ab: (a: A) => B, bc: (b: B) => C): (a: A) => C
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export function flow<A, B, C, D>(
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ab: (a: A) => B,
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bc: (b: B) => C,
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cd: (c: C) => D
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): (a: A) => D
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export function flow<A, B, C, D, E>(
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ab: (a: A) => B,
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bc: (b: B) => C,
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cd: (c: C) => D,
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de: (d: D) => E
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): (a: A) => E
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export function flow(
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...fns: Array<(x: unknown) => unknown>
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): (a: unknown) => unknown {
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return (a: unknown) => fns.reduce((acc, fn) => fn(acc), a)
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}
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src/prelude/index.ts
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src/prelude/index.ts
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export * from "./compose"