Re: (set! (@@ MOD NAME) EXP) considered harmful

[Ludovic Courtès]

Hello!

Neil Jerram <address@hidden> writes:

> (Ludovic recently suggested an optimization for constant additions, and
> I assumed that would require this kind of rollback, if the definition of
> `+' was later changed.)

I generally agree with the praise of dynamicity, but there’s a tension
between dynamicity and performance.

Mark’s example is a good illustration.  Likewise, many optimizations
sacrifice dynamicity: open coding (see ‘*primcall-ops*’ and
‘vm-i-scheme.c’), inlining, constant folding, etc.

One could event argue that the mixture of code affected by these
optimizations and unaffected code is fragile in the presence of global
redefinitions.

Perhaps the compiler should make it possible to choose a tradeoff
between dynamicity and performance, e.g., by actually honoring the ‘:O’
compile option?

Thanks,
Ludo’.