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Comment by skishore | Hacker News Reader

The type of a curried function in Typescript is just something like:

  (a: number) => (b: number) => (c: number) => number

Sure, the parameter names and parentheses are a bit annoying, but I wouldn't call that "very verbose". Comparable concepts in C++ or Java would be a nightmare to type out.

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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.

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

While Java’s option is quite painful

    Function<Number, Function<Number, Function<Number, Number>>>

The same in Kotlin is actually okayish:

    (Number) -> (Number) -> (Number) -> Number

I can't speak to Typescript but check out the Flow types for Ramda: https://github.com/flowtype/flow-typed/blob/master/definitio...

Maybe just a matter of perception but it looks verbose to me.

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