Groovy and the Lambda Calculus

I've been playing around with the Groovy language, and have recently been involved in a discussion regarding the addition of closures to Java. Tangents lead to tangents, and all of a sudden, I find myself reading about Perl and the Lambda Calculus. Oy.

I had just started trying to get my head around the idea of the lambda calculus when the author brought up the subject of "currying", and discussed the "Lambda Calculus Way"™ of writing an addition function built on the concept that functions can only take a single argument. The author showed how to express such a thing in Perl:

    sub add {
        my $x = shift;
        my $f = sub {
            my $y = shift;
            return $x + $y;
        }
        return $f;   
    }

Groovy supports writing code like this too, so I thought I'd see what I could come up with in Groovy syntax. Here's the beast:

    def add (x) {
        return {
            y -> return x + y
        }
    }

And the test...

    assert 7 == add(3)(4) // whew.

If there's a Groovy expert out there reading this blog, let me know if there's a better way. All right, back to the essay...