In Typescript, define a type for an array where the first element is more specific than the rest

Question

I would like to define a type for an array whose first element is a specific type (e.g. Function), and the remaining elements are the empty type. For example:

type FAs = [Function, {}, {}, {}, ...]; // pseudo code 

Is such a thing possible?

The purpose is to provide a single-argument function like this:

const myCaller = ([fun, ...args]: FAs) => fun.apply(args); 

An alternative approach would be to use two arguments to myCaller, like this:

const myCaller = (fun: Function, args: any[]) => fun.apply(args); 

but for aesthetic reasons I would prefer to use a single argument. I also wonder if the type system supports what is arguably an arbitrary-length tuple. Maybe such a thing is undesirable for computer science reasons I don't understand.

Answer 1

In current versions of Typescript this is possible using array spread:

type FAs = [Function, ...Array<{}>]

It supports any length from 1 to n (the first element is required).