min(selector?): PartialLens

ts
min: <A extends number>() => PartialLens<A, A[]>;
min: <A>(selector?: (a: A) => number) => PartialLens<A, A[]>;

ts
min: <A extends number>() => PartialLens<A, A[]>;
min: <A>(selector?: (a: A) => number) => PartialLens<A, A[]>;

---

This combinator, when passed to derive, returns an optic focused on the lowest number from the focused array.

ts
import { min } from "@optics/react/combinators";
 
const minOptic = createState([42, 16, 98, 123, 8]).derive(min());
 
minOptic.get(); // 8
 
minOptic.set(20);
 
minOptic.get(); // 16

ts
import { min } from "@optics/react/combinators";
 
const minOptic = createState([42, 16, 98, 123, 8]).derive(min());
 
minOptic.get(); // 8
 
minOptic.set(20);
 
minOptic.get(); // 16

Here 8 is the min element, and when we set it to 20 then the element at index 1 (16) becomes the min element.

Selector

If the elements in the focused array aren't numbers, then you must provide a selector to get a number from each element in the array:

ts
import { min } from "@optics/react/combinators";
 
const usersOptic = createState([
  { name: "Jack", age: 23 },
  { name: "Jeanne", age: 56 },
]);
 
const youngestUserOptic = usersOptic.derive(min((user) => user.age));
 
youngestUserOptic.get(); // { name: "Jack", age: 23 }
 
usersOptic[1].age.set(18);
 
youngestUserOptic.get(); // { name: "Jeanne", age: 18 }

ts
import { min } from "@optics/react/combinators";
 
const usersOptic = createState([
  { name: "Jack", age: 23 },
  { name: "Jeanne", age: 56 },
]);
 
const youngestUserOptic = usersOptic.derive(min((user) => user.age));
 
youngestUserOptic.get(); // { name: "Jack", age: 23 }
 
usersOptic[1].age.set(18);
 
youngestUserOptic.get(); // { name: "Jeanne", age: 18 }