Zelphir: > I don't really understand the (in-list ...) thing. This seems to be internal magic to me. Maybe it informs about the type of what is iterated over and that makes it faster?
Pretty much. Here's a program that constructs a lot of random numbers and adding them up in a few different ways. #lang racket (define random-list (build-list 500000 (λ (n) (random 100)))) (define random-vector (list->vector random-list)) (define (sum-generic xs) (for/sum ([i xs]) i)) (define (sum-list xs) (for/sum ([i (in-list xs)]) i)) (define (sum-vector xs) (for/sum ([i (in-vector xs)]) i)) (displayln "Sum a List: Generic vs Specific (with in-list)") (time (sum-generic random-list)) (time (sum-list random-list)) (newline) (displayln "Sum a Vector: Generic vs Specific (with in-vector)") (time (sum-generic random-vector)) (time (sum-vector random-vector)) (newline) (displayln "Specialisation limits applicability") (sum-list random-vector) Output: Sum a List: Generic vs Specific (with in-list) cpu time: 161 real time: 178 gc time: 0 24772117 cpu time: 33 real time: 41 gc time: 0 24772117 Sum a Vector: Generic vs Specific (with in-vector) cpu time: 113 real time: 114 gc time: 0 24772117 cpu time: 36 real time: 40 gc time: 0 24772117 Specialisation limits applicability . . in-list: contract violation expected: list? given: '#(12 44 14 8 10 81 33 56 78 32 95 43 96 34 52 46 59 5 29 86 91 44 38 87 28 25 62 85 46 4 39 44 19 47 76 53 14 17 11 47 55 47 55 58 31 82 15 51 23 21 25 91 82 30 86 99 99 91 94 93 75 40 28 61 23 28 40 65 58 62 14 87 72 67 94 8 81 76 1 10 3 48 95 7... Dan -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
