Discussion on: Pragmatic types: Redux as Finite State Machine

[stereobooster]

It appears it is pretty easy in TS

type ActionTypes = 'increment' | 'reset'
const reducers: { [key in ActionTypes]: () => void } = {
    increment: () => {},
    reset: () => {}
}

[stereobooster]

And with Flow too

type ActionTypes = 'increment' | 'reset' 
const reducers = {
    increment: () => {},
    reset: () => {}
}
const reducer = (a: ActionTypes) => {
  const r = reducers[a];
}

[Mihail Malo]

Making them take the correct Action object is the more hacky part.
But I guess it makes sense, switch takes place inside function body, which does more inference, while the lookup is statically declared functions, which always requires more annotation.