On Sun, Aug 1, 2010 at 11:31 PM, Todd O'Bryan <toddobr...@gmail.com> wrote: >> 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))))))) >> > Right. But we don't let students do that! We don't even let them use > ". rest" arguments for gosh sake! :-) >
Right? What is "natural" about that? In my lonely corner of the woods students would see nothing natural about the above. Well, not at the beginning that is. > But do we really want to have to introduce another function just to > make the naming prettier? Alternatively, do we really want to have to > introduce another piece of syntax just to make the naming prettier? > Both approaches have negatives. (define (distance p1 p2) ((lambda (x1 y1 x2 y2) (sqrt (+ (sqr (- x1 x2)) (sqr (- y1 y2))))) (posn-x p1) (posn-y p1) (posn-x p2) (posn-y p2))) "Introducing another function" *is* precisely what you are doing when you use let. The added syntax "let" is just sugar coating for this common practice. -- Cheers, Marco _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
