I first experimented with Lisp back in the mid-80’s, and have returned to it time and again—not as a language for serious projects, but just as a way of learning new techniques and new ways to think about writing software. I’ve tried using Racket on a number of occasions going back to way before it was called that, and something about the software just puts me off. Perhaps I could get past that if I stuck with it, but I just can’t see myself writing a large project using Racket.
I liked it many years ago but when I noticed how slow and heavy my code was I left it. It manages to be slower than Python. Perhaps the Chez Scheme rewrite helped with that but now if I need a Lisp I have Common Lisp which is super fast and lightweight enough.
These are small benchmarks, so don’t over-generalize from this data point alone, but Racket absolutely crushes Python in terms of speed and goes speedily enough against other popular performance-focused languages:
Matthew Flatt, the Racket lead, says that Racket’s performance should be fairly comparable to Java, much faster than Python, slower than Julia/Rust/etc. That’s been a helpful model for me: if Java is fast enough, Racket will do fine.
Nice examples! With a few tricks, I made the Racket program x5 faster. I think you tried to use the simplest program, so I tried to add as few cheats as possible. I added a happy path for fixnums and keep the slow path in case the iterations gets too big:
(define (count-collatz n [cnt 1])
(if (fixnum? n)
(cond
[(= n 1) cnt]
#;[(zero? (unsafe-fxremainder n 2)) (count-collatz (unsafe-fxquotient n 2) (+ 1 cnt))]
[(zero? (fxand n 1)) (count-collatz (unsafe-fxquotient n 2) (+ 1 cnt))]
[else (count-collatz (+ (* 3 n) 1) (+ 1 cnt))])
(cond
[(= n 1) cnt]
[(even? n) (count-collatz (/ n 2) (+ 1 cnt))]
[else (count-collatz (+ (* 3 n) 1) (+ 1 cnt))])))
My program has two versions, the version with `fxand` is slightly faster than the versions with `fxremainder`. I have to used two `unsafe-` functions, but a smart enough optimizer should have fixed them. So I'm adding this example to my wishlist.
I think it would be very hard for the optimizer would be to replace `/` with `quotient`, but the rest look possible.
But if you run the code inside the default IDE call DrRacket, you must go to the menu Language>Choose_Language... then click "Show_Details" and disable "Debugging".
With debugging enabled, you get nicer error messages, but it blocks a lot of optimizations and the program get slow.
I wonder how, given that anything that brings Python and performance together, usually means it is actually C code, or similar, as PyPy is seldom reached for.
Raket is compiled, thus maybe not the right build parameters?
