To John: The original poster was asking why the comparison operators do not generalize downward to 1-ary and 0-ary versions. Upward generalization works.
On Fri, Oct 28, 2011 at 9:31 AM, Arthur Nunes-Harwitt <a...@cs.rit.edu> wrote: > Hi, > > That's the wrong question. Well, sort of. > Recall that (= x1 x2 x3 ... xn) means > (x1 = x2) & (x2 = x3) & ... & (xn-1 = xn). Yes, but I was generalizing in a different way: (define (binary-add a b) (+ a b)) (define (binary-multiply a b) (* a b)) (define (binary->nary op base-case) (lambda args (fold-left op base-case args))) ; ***** (define add (binary->nary binary-add 0)) (define multiply (binary->nary binary-multiply 1)) (The line with asterisks is because it is not specified whether OP is left-associative or right-associative. Fortunately, add and multiply work both ways.) -- ~jrm _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
