Simpler type annotation

[ivan-demchenko]

Summary

Sometimes, we have to specify arguments to functions that are not really needed. For example, in function intefaces.

Actual

As a dummy example, consider this snippet:

interface Functor<A> {
    fmap<B>(f: (x: A) => B): Functor<B>
}

interface MyFnInterface1<B, C> {
    (x: B, y: B): Promise<C>
}

interface MyFnInterface2<B, C> {
    (fn: (x: B, y: B) => C): Promise<C>
}

Would be nice to have

The snippet above could be simplified as the following:

interface Functor<A> {
    fmap<B>((A) => B): Functor<B>
}

interface MyFnInterface1<B, C> {
    (B, B): Promise<C>
}

interface MyFnInterface2<B, C> {
    ((B, B) => C): Promise<C>
    ((B) => (B) => C): Promise<C>
}

or, even to this:

interface Functor<A> {
    fmap<B>(A => B): Functor<B>
}

interface MyFnInterface1<B, C> {
    (B, B): Promise<C>
}

interface MyFnInterface2<B, C> {
    ((B, B) => C): Promise<C>
    (B => B => C): Promise<C>
}

[gcnew]

It has already been suggested numerous times. See #13152

[RyanCavanaugh]

Duplicate of #3081