The lexer for Ocaml mistakenly finds an error in
because the name _a starts with an underscore.
I use Pygments version 1.3.1 (Debian version 1.3.1+dfsg-1).
By the way, I didn’t understand why the regexp for the Name token is different between the state 'root' and the state 'dotted': in both cases it should be r'[a-z_][A-Za-z0-9_\']*', no? (I don't really understand why the A-Z is omitted either, even though the lexer understands capital letters in names in that rule).