Multiple parameter closure argument type not inferred

Question

I have a piece of code that I can\'t get to behave in the way I\'d like. I have a class defined in the following way (stripped down for this):

class Behaviou         


        

Answer 1

One of the ways to fix this is to define multiple argument lists. So your map1 method would be defined like this:

def map1[U, V](behaviour: Behaviour[U])(func: (T, U) => V): Behaviour[V] = ...

and you can use it like this:

beh.map1(beh2)((a, b) => a + b)
beh.map1(beh2)(_ + _)

I'm not completely sure why type inference does not work in your case, but I believe that it has something to do with usage of U type parameter. You are using it twice - for the first and second argument. It's probably too complicated for compiler to figure it out. In case of 2 argument lists, U would be inferred during first argument list compilation, and the second argument list will use already inferred type.