How to declare the interface of a NAMED function in Typescript?

Issue

I can define the interface of a function:

interface Handler {
  (state: IState, action: IAction): IState;
}

Then I can declare a function that satisfies the interface:

let selectRegimen: Handler = function(state, action) {
  return state;
};

But what about named (as in, not anonymous) function? Obviously, I could do something like this:

let selectRegimen: Handler = function selectRegiment(state, action) {
  return state;
};

...but something feels strange about that syntax. Is there a better way to handle this?

Solution

There's no way to force a specific name in a named function expression just like there's no way to force a specific variable name to assign the function to.

What you are doing is fine though you could use a type alias instead of an interface if you find that better suits your taste:

type Handler = (state: IState, action: IAction) => IState;

Answered By - David Sherret