adyatan

If I tell you the getter of my lens is user => user.age and ask you what would the setter (without any guards or logic) be? You would say (age, user) => ({ ...user, age }). The point being in some cases the setter can be derived from the getter, but we still explicitly write our setters. Adyatan (hindi for "update") gives an alternative...

import setter from "adyatan";

const getNameAge = user => [user.name, user.age];
const setNameAge = setter(getNameAge);
// equivalent to
// const setNameAge = ([name, age], user) => ({ ...user, name, age })

setNameAge(["Devansh", 20], {})
// { name: "Devansh", age: 20 }

You'd usually pair it with some lens library, eg...

import { useProfunctorState as _useProfunctorState } from "@staltz/use-profunctor-state"
import setter from "adyatan";

const useProfunctorState = (...a) => {
  let s = _useProfunctorState(...a)
  return ({
    map: get => s.promap(get, setter(get)),
    promap: (...a) => s.promap(...a)
  })
}

// Without adyatan
_useProfunctorState({ a: 0 }).promap(x => x.a, (a, x) => ({ ...x, a }))

// With adyatan
useProfunctorState({ a: 0 }).map(x => x.a)

Now obviously it works only for cases where you're just changing the structure ie no "logic" involved. Also it's meant to be a toy, YOLO if you want to use it anyways.