Try disassembling it. I suspect the for-each is inlined, and that whatever is going on involves instruction explosion which means you get a lot more optimization opportunities.
That difference seems large though. Try it in guile 2.2 (which shouldnt have the same opportunities for optimization). -- Linus Björnstam On Sun, 7 Jun 2020, at 08:27, Aleix Conchillo Flaqué wrote: > Hi, > > in the latest guile-json, 4.1.0. I changed some code to use > for-each+string->list. The performance seemed nice and I released it. > > Christopher Lam pointed out that I could have used string-for-each instead. > I made the change but the performance degraded a lot: > > string-for-each: > > scheme@(json parser)> ,t (->bool (scm->json-string json)) > $19 = #t > ;; 17.909537s real time, 18.063382s run time. 0.207281s spent in GC. > > vs > > for-each + string->list: > > scheme@(json parser)> ,t (->bool (scm->json-string json)) > $20 = #t > ;; 2.998381s real time, 3.319349s run time. 0.471969s spent in GC. > > string-for-each is implemented in scheme here, if Im not wrong: > > http://git.savannah.gnu.org/cgit/guile.git/tree/module/rnrs/base.scm#n89 > > string->list and for-each would use C. > > Is that huge gap expected? > > This is with Guile 3.0.2. > > Best, > > Aleix >
