Compose and andThen methods

Question

I\'m following the tutorial Pattern matching & functional composition on Scala compose and andThen methods. There\'s such an example:

Answer 1

addAhem is a method. compose method is defined on functions. addAhem _ converts addAhem from method to function, so compose can be called on it. compose expects a function as it's argument. You are giving it a method addUmm by converting addUmm into a function with addUmm _ (The underscore can be left out because the compiler can automatically convert a method into a function when it knows that a function is expected anyway). So your code:

addAhem _ compose addUmm

is the same as

(addAhem _).compose(addUmm)

but not

addAhem(_).compose(addUmm(_))

PS I didn't look at the link you provided.