On 2013-05-31 19:40:52 -0400, Asumu Takikawa wrote: > Is it feasible to get `member` to have the same optional argument > behavior as `assoc`? That is, to have an equality predicate as the third > argument.
I went ahead and implemented this behavior and submitted a pull request: https://github.com/plt/racket/pull/366 To see if the change is "pay as you go", I ran some microbenchmarks to see if old-style `member` calls would slow down (see below). There doesn't seem to be any significant slow-down AFAICT. I was surprised that the non-JIT version was faster in the first case but much slower in the second microbenchmark though. (note: I had to change the C implementation of `member` for the non-JIT path) I'd appreciate any suggestions on the code. Cheers, Asumu ;;; NEW BRANCH $ racket member-benchmark.rkt cpu time: 1748 real time: 1752 gc time: 0 $ racket --no-jit member-benchmark.rkt cpu time: 1524 real time: 1526 gc time: 0 ;;; MASTER $ racket member-benchmark.rkt cpu time: 1712 real time: 1716 gc time: 0 $ racket --no-jit member-benchmark.rkt cpu time: 1524 real time: 1528 gc time: 0 The microbenchmark is just this: #lang racket/base (require (only-in racket/list range)) (define lst (range 1 5000)) (time (for ([i 30000]) (member 2500 lst))) On a slightly different microbenchmark: ;;; NEW BRANCH $ racket member-benchmark-2.rkt cpu time: 2396 real time: 2402 gc time: 0 $ racket --no-jit member-benchmark-2.rkt cpu time: 7156 real time: 7174 gc time: 0 ;;; MASTER $ racket member-benchmark-2.rkt cpu time: 2412 real time: 2416 gc time: 0 $ racket --no-jit member-benchmark-2.rkt cpu time: 6892 real time: 6911 gc time: 0 #lang racket/base (define lst '(a b c)) (time (for ([i 30000000]) (member 'b lst))) _________________________ Racket Developers list: http://lists.racket-lang.org/dev
