A common technique in functional programming is the concept of currying. Currying is the process of transforming a function that accepts multiple parameters into a series of functions, each of which accepts a single function. Take the following definition of foo:
fun foo(a: String, b: Int) : Boolean
The curried form would look like the following:
fun foo(a: String): (Int) -> Boolean
Note that the curried foo returns a second function, which in turn, when invoked with an Int type, would return the Boolean type as before. Currying is a useful technique for allowing functions with multiple parameters to work with other functions that only accept single arguments.
Currying is related to the idea of partial application. Partial application is the process by which some, but not all, of the parameters of a function are specified in advance, returning...