...

I wasn't aware of that paragraph in the report until recently, and as far as I know none of the current Haskell implementations implement the '\uhhhh' escape sequences.

One reason to use this approach would be if there already existed a preprocessor to do the job - does anyone know of one? If not, I think the paragraph could be deleted in favour of using appropriate encodings for source files (I'd planned to implement at least UTF-8 in GHC at some point).

This means that internally GHC will treat or represent 'Char' as 32-bit integer ?

Yes, in GHC Chars are 32 bits. HsChar is a 32-bit integral type in C. Cheers, Simon