Eduardo Cavazos wrote:
The trouble with that is, in an expression like this:
(define fib
(ifte (less-than= 1)
(constant 1)
(bi (uni (sub 1) (lambda (x) (fib x)))
(uni (sub 2) (lambda (x) (fib x))) +)))
you end up with a procedure which when called does a ton of allocation.
There's a similar problem with the version of curry which I posed awhile
back.
(define-syntax curry
(syntax-rules ()
((curry (f x)) f)
((curry (f x y ...))
(lambda (x)
(curry ((lambda (y ...)
(f x y ...))
y ...))))))
Let's make a 'sub' procedure in a purely higher-order fashion:
(define (swap c)
(lambda (x y)
(c y x)))
(define sub (curry ((swap -) x y)))
(let ((f (sub 5)))
(time (f 10)))
running stats for (f 10):
no collections
0 ms elapsed cpu time, including 0 ms collecting
0 ms elapsed real time, including 0 ms collecting
8 bytes allocated
This curry fixes the problem:
(define-syntax curry
(syntax-rules ()
((curry (f x)) f)
((curry (f x y ...))
(let ((f* f))
(lambda (x)
(curry ((lambda (y ...)
(f* x y ...))
y ...)))))))
running stats for (f 10):
no collections
0 ms elapsed cpu time, including 0 ms collecting
0 ms elapsed real time, including 0 ms collecting
0 bytes allocated
By the way, 'sub-from' is:
(define sub-from (curry (- x y)))
Ed
