Bison *must* be optional.
why *must* it be optional? arguments about "standard tools" fall flat
because a standard win 32 system lacks a compiler anyway... There are many
bison implementations, including win 32 or dos versions.
As was mentioned bison is one of the most standard compiler generation
tools... available from many places, including installed as a standard
package in many linux distribs.
i believe in make things work first, then make them better.
my 0.02...
Youness