Hello Simon (et al.), While doing #9224[1] as a finger-exercise to extend the lexer to support base-2 integer literals, I got stuck on the lexer extension map being represented as an 'Int', which (in GHC) is only guaranteed to hold least 32bits. -- for reasons of efficiency, flags indicating language extensions (eg, -- -fglasgow-exts or -XParallelArrays) are represented by a bitmap -- stored in an unboxed Int However, as all 32bits are already taken up by language extensions, and I'd need a 33th bit, I'm wondering how to proceed. Can we replace the 'Int' by an 'Int64' (or even better a Word64, ideally with a newtype or at least a type-synonym around it?) which would give us a bit more headroom while being semantically sound even for 'bitSize Int == 32'? [1]: https://ghc.haskell.org/trac/ghc/ticket/9224 Cheers, hvr