How can I combine two Function0 val's into one Function0

I imagine something like this:

def combine[A, B, C](f: (A, B) => C): (M[A], M[B]) => M[C]

while M would be Function0. Is this possi开发者_运维技巧ble in scalaz?

import scalaz._; import Scalaz._

def combine[A, B, C, M: Applicative](f: (A, B) => C) = 
   (ma: M[A], mb: M[B]) => (ma |@| mb)(f)

In standard scala it is not that hard, simply stick to your signature:

def combine[A,B,C]( f: (A,B) => C ) 
  = ( fA:(()=>A), fB:(()=>B) ) => f( fA(), fB() )

Here is a small example:

scala> val isProdPositive = combine( (i:Int,d:Double) => i*d > 0.0 )
  isProdPositive: (() => Int, () => Double) => Boolean = <function2>

scala> val f1 = () => 2
  f1: () => Int = <function0>

scala> val f2 = () => -1.5
  f2: () => Double = <function0>

scala> isProdPositive(f1,f2)
  res1: Boolean = false