Would anyone happen to have lying around parser/lexer for block
indented code (a la Python and Haskell)? I am using ocamlyacc or
menhir, whichever.

It seems to be the best way to do deal with this is to put a filter
between lexer and parser that inserts appropriate hints. I would like
to avoid reinventing the wheel, hints and advice are appreciated.

With kind regards,

Andrej