How to use / refer to the negation of a boolean function in Scala?

Question

I\'m trying to use the negation of a boolean function in Scala, such as:

def someFunction(x: Set, p: Int => Boolean): Boolean = 
    someOtherFunction(x,          


        

Answer 1

Another way to solve it without the use of an anonym function is to define a concrete function for this task.

def even(x:Int):Boolean = x%2==0
def not(f: Int => Boolean): Int => Boolean = !f(_)
def odd = not(even)
odd(1) // true
odd(2) // false

You can also define ! yourself

def even: Int => Boolean = _%2==0
implicit def bangy(f: Int => Boolean) = new { def unary_! : Int => Boolean = !f(_) }
def odd = !even
odd(1) // true
odd(2) // false

but this only seems to works for functions of type Int=>Boolean, and not (Int)=>Boolean. The not(even) solution works with both.