fp-pipe-ref

# pipe & flow Quick Reference ## pipe - Transform a Value ```typescript import { pipe } from 'fp-ts/function' // pipe(startValue, fn1, fn2, fn3) // = fn3(fn2(fn1(startValue))) const result = pipe( ' hello world ', s => s.trim(), s => s.toUpperCase(), s => s.split(' ') ) // ['HELLO', 'WORLD'] ``` ## flow - Create Reusable Pipeline ```typescript import { flow } from 'fp-ts/function' // flow(fn1, fn2, fn3) returns a new function const process = flow( (s: string) => s.trim(), s => s.toUpperCase(), s => s.split(' ') ) process(' hello world ') // ['HELLO', 'WORLD'] process(' foo bar ') // ['FOO', 'BAR'] ``` ## When to Use | Use | When | |-----|------| | `pipe` | Transform a specific value now | | `flow` | Create reusable transformation | ## With fp-ts Types ```typescript import * as O from 'fp-ts/Option' import * as A from 'fp-ts/Array' // Option chain pipe( O.fromNullable(user), O.map(u => u.email), O.getOrElse(() => 'no email') ) // Array chain pipe( users, A.filter(u => u.active), A.map(u => u.name) ) ``` ## Common Pattern ```typescript // Data last enables partial application const getActiveNames = flow( A.filter((u: User) => u.active), A.map(u => u.name) ) // Reuse anywhere getActiveNames(users1) getActiveNames(users2) ```