Hi Matthias,
On 01/20, Matthias Felleisen wrote: > I can confirm a serious speed-up with the explicit vector-ref inside the for > loop instead of the for-loop lookup with (in-vector ...). I get from 20s to > 12s on my reasonably new (small) macair. > > When you look at the expansion, you see the expected two-argument for-loop > function with two arguments instead of one. You will also see an > unsafe-vector-ref for the for-loop, while our code contains a normal > vector-ref. So the question is whether the compiler generates code for > two-argument recursive functions that is so much worse than for a > one-argument function with a safe vector ref. Curious. I've tested your revised version - here's the output: Output: cpu time: 26907 real time: 26979 gc time: 142 It is 1~2 seconds faster but not much. Maybe this is its limit? Here's two additional questions: 1. how can I check the expansion of the for-loop? I'm using the Racket REPL from CLI. 2. I've noticed that the let-form in my code is replaced by "define", is this the preferred coding style? Thanks. -Limbo Peng ____________________ Racket Users list: http://lists.racket-lang.org/users
