https://www.reddit.com/r/Julia/comments/17m7knl/same_code_in_julia_takes_6_minutes_vs_15_seconds/
const s = 6;
const L = sqrt(11);
r(z) = 1 ./sqrt.(s^2 - (L-z).^2)
That’s part of larger code that was 24x slower than needed, or even more.
I believe it was (before changing at reddit, the only needed change?):
s = 6;
L = sqrt(11);
before, and even a simple demo of the problem would be:
r(a) = a + L
@code_native r(1) # the compiler obviously knows of this global problem.
I would want when defining:
julia> r(a) = a + L
WARNING: that is a speed-trap referring to non-const global L, but it's perfectly ok for interactive calculator use.
What are the worst speed-traps? I could foresee this on by default in the REPL, could be turned off, and maybe degrees a threshold of alerting depending on seriousness.