how to use identity.ap on generic functions?

[rolivegab]

import { identity } from "fp-ts";

const FT =
  <A>(a: A) =>
  <B>(b: B) => {
    return [a, b] as const;
  };

const a = pipe(
  FT,
  FT1 => FT1(123),
  FT2 => FT2('asd')
) // readonly [number, string] (it works, nice!)

const b = pipe(
  FT,
  identity.ap(123),
  identity.ap('asd')
) // readonly [unknown, unknown] (I want to do the same here, looks that it's not possible :/)

I also tried to write my own version for generics, but...

const apply = <Param>(fa: Param) => (fab: <B>(a: Param) => B) => fab(fa) as ReturnType<typeof fab<typeof fa>>;

const c = pipe(
  FT,
  apply(123),
  apply('asd')
) /* Argument of type '<A>(a: A) => <B>(b: B) => readonly [A, B]' is not assignable to parameter of type '<B>(a: number) => B'.
  Type '<B>(b: B) => readonly [number, B]' is not assignable to type 'B'.
    'B' could be instantiated with an arbitrary type which could be unrelated to '<B>(b: B) => readonly [number, B]'.ts(2345) */

[orangebokov]

any answers?

[samhh]

fp-ts-std has Fn.ap: https://samhh.github.io/fp-ts-std/modules/Function.ts.html#ap

TypeScript struggles with inference so you may need to concretise your f in pipe(F.of(f), F.ap(g), F.ap(h)).