Logic

Predicate combinators

both<A>(p1: (a: A) => boolean, p2: (a: A) => boolean): (a: A) => boolean
either<A>(p1: (a: A) => boolean, p2: (a: A) => boolean): (a: A) => boolean
allPass<A>(preds: ((a: A) => boolean)[]): (a: A) => boolean
anyPass<A>(preds: ((a: A) => boolean)[]): (a: A) => boolean

import { pipe, A, Logic } from '@stopcock/fp'

const isAdult = (u: User) => u.age >= 18
const isActive = (u: User) => u.active

pipe(users, A.filter(Logic.both(isAdult, isActive)))

Control flow (dual)

equals<A>(a: A, b: A): boolean
defaultTo<A>(opt: A | undefined, fallback: A): A
when_<A>(value: A, pred: (a: A) => boolean, f: (a: A) => A): A
unless<A>(value: A, pred: (a: A) => boolean, f: (a: A) => A): A
cond<A, B>(value: A, conditions: [(a: A) => boolean, (a: A) => B][]): B | undefined

import { pipe, Logic } from '@stopcock/fp'

pipe(undefined, Logic.defaultTo(0))  // 0
pipe(5, Logic.defaultTo(0))          // 5

pipe(
  score,
  Logic.cond([
    [s => s >= 90, () => 'A'],
    [s => s >= 80, () => 'B'],
    [s => s >= 70, () => 'C'],
    [() => true,   () => 'F'],
  ]),
)