Create polymorphic (generic) action creator

[anilanar]

I have created an action such as:

export const foo = createAction(
  'FOO',
  resolve => <S extends string>(s: S) => resolve(s),
);

The action type is correct, the output function has the correct generic constraints and types.

However, using such an action creator with createReducer causes type of action to be never in the handler function.

This is a simplified version of the actual use case. We really do use polymorphic actions in a useful way.

[the-dr-lazy]

This looks like as a design limitation in TypeScript.

I don't see anyway to infer polymorphic action type.

declare const foo: <S extends string>(s: S) => { type: 'FOO', payload: S }

type Action = ReturnType<typeof foo> //=> any

@anilanar do you have any idea?

[anilanar]

You are right @the-dr-lazy, it's currently not possible.