[tommikaikkonen]

I agree, that doesn't look bad. However, this type definition forces you to supply one argument per function call, which looks awful in JavaScript:

    fn(1)(2)(3)

That's a big drawback for me. Libraries like Ramda allow one or more arguments per function call:

    fn(1, 2, 3) === fn(1, 2)(3) === fn(1)(2, 3)

That's what makes the verbosity unbearable, as each type of call needs its own type.

[noppa]

At least in Flow it's actually possible to properly type curried functions!

Here's a gist of the type definitions I'm using: https://gist.github.com/noppa/c600cc43fd44e33768efe6c6eec4a9...

I think something similar might work in TS too.

Demo: https://goo.gl/w3aPsw