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, !p)

But I get the error:

 value unary_! is not a member of Int => Boolean

How can I refer to the negation of p?

Answer 1

The negation of p is a function that applies p to its argument and negates the result.

x => !p(x)

If you want to be able to write !p or p && q you can use this library, which pimps functions that return a bool with various logical operators.