A taste of the curry

There is another way we can write the method, where each parameter is enclosed in parenthesis. For example, the modBy2 method can also be written as follows:

scala> def modBy2(n: Int)(d: Int) = n % d 
modBy2: (n: Int)(d: Int)Int 

scala> modBy2(10)(3) 
res0: Int = 1 

This form is called currying. Currying allows us to turn a function that expects two arguments into a function that expects only one.

By applying currying to modBy2, we get back another function:

scala> modBy2 _ 
res3: Int => (Int => Int) = <function1> 

This is a function that takes in an Int parameter, n. It returns another function, which takes yet another Int parameter, d. This function finally returns the result, which is Int. Well, here is the diagrammatic representation of currying:

Figure 6.4: The currying function

If we just specify the value for n, we get a partially applied function again:

scala> modBy2(10) _ 
res5: Int => Int = <function1> 

scala> val p = modBy2...