Haskell source encoding

Question

The Haskell 2010 Language Report says:

Haskell uses the Unicode [2] character set. However, source programs are currently biased toward the ASCII character set

Answer 1

While the Haskell standard simply says Unicode the set of possible characters (as opposed to e.g. ASCII or Latin-1) it doesn't specify which of the several different encodings (UTF8 UTF16, UTF32, byte order) to use.

Alex, the lexer that comes with the Haskell Platform requires its input to be UTF8 encoded ^* which is why you see the code you mention. In practice I think all the major implementations of Haskell require source to be in UTF8.

* - This is actually a real problem as GHC stores strings and more importantly Data.Text internally as UTF16. It would be nice to be able to lex these directly rather then converting back and forth.