[racket] syntax, differently

On Aug 1, 2010, at 8:05 PM, Todd O'Bryan wrote:

> In a language with typing and
> overloading, you could define two distance functions, one that takes
> two posns and another that takes four numbers, and I think this would
> be the most natural way to write distance.


Like this: 

(define distance
  (case-lambda
   ((p q) (distance (posn-x p) (posn-x q) (posn-y p) (posn-y q)))
   ((x0 y0 x1 y1) (sqrt (+ (sqr (- x0 y0)) (sqr (- x1 y1)))))))

(distance (posn 3 4) (posn 0 0))