is there a nice way to partially apply function in...

# functional

[Vladyslav Sitalo]

is there a nice way to partially apply function in Kotlin to get another function. I’m looking for something like:

fun manyParamFun(p1: Int, p2: String, p3: List<String>): String = ...
val newFun  = bind(::manyParamFun, p1=5) // to get (String, List<String>) -> String function

I know we can do things like

fun newFun(p2: String, p3: List<String>): String = manyParamFun(5, p2, p3)

but I’m looking for a nicer way..

[Rob]

How’s this?

Untitled

[Vladyslav Sitalo]

thanks for the suggestion! that can be an option, let me play with it. I’d like a version with arbitrary number of arguments though 🙂

[Rob]

Unfortunately, there isn’t a way to make it work for any number of arguments without losing type information. Scala has the same limitations. I believe they generate their standard library code to handle up to an arbitrary number of parameters.

[Vladyslav Sitalo]

I see, thanks!

[wakingrufus]

Arrow Kt provides a curry extention function for Function2

inline fun <A, B, Z> ((A, B) -> Z).curry(): (A) -> (B) -> Z = { p1: A -> { p2: B -> this(p1, p2) } }

[wakingrufus]

you could probably write your own based on that for higher arity