Elm Functions

Notes about functions in elm, most notably partial application.

Partial Application

It is basically breaking down a function, by constituing its argument with another function, to make it more readable. In elm, all functions take exactly one argument and return a result, which can be another function

add : number -> number -> number
add x y =
    x + y

add2 = add 2
var1 = add2 3
-- returns 5

var2 = 3
    |> add2
-- returns 5

var3 = 4
    |> add2
    |> add 7
-- returns 13

Breakdown

• As you probably notice there are two ->, this means that add 2 3, is actually implemented as (add 2) 3
• Function add2 is basically covers add 2 part of add 2 3
• Pipe | is to make it easier to read, 4 is passed to a partially applied function add2 which finally passed as a second argument for add. The first argument is 7
• This is similar to currying. But they are not the same