Artur Skawina:
You mention AAs, so you may already realize this, but there is noneed for a mod ctor in the above example:immutable bool[256] tab2 = { bool t[256]; for (size_t u = 0; u < 0x100; ++u) t[u] = isIdentifierChar0(cast(ubyte)u); return t; }();
A recent improvement in foreach loops allows to remove the cast from your code, but I have found a new compiler bug:
https://d.puremagic.com/issues/show_bug.cgi?id=12504 Bye, bearophile