maybeCall.ts

type UnaryFn<T, R> = (param: T) => R

export function maybeCall<T, R>(fn: UnaryFn<T, R>): UnaryFn<T | null, R | null>;
export function maybeCall<T, R>(fn: UnaryFn<T, R>, value: T | null): R | null;
export function maybeCall<T, R>(fn: UnaryFn<T, R>, value?: T | null) {
  if (value === undefined) {
    return (v: T | null) => maybeCall(fn, v)
  }
  return value !== null ? fn(value) : null
}