Section 2.6. of the Haskell report says:
A string may include a "gap"---two backslants enclosing white characters---which is ignored. This allows one to write long strings on more than one line by writing a backslant at the end of one line and at the start of the next. For example,
"Here is a backslant \\ as well as \137, \ \a numeric escape character, and \^X, a control character."
ghc-5.02.2 cannot parse string gaps. It accepts \ at the end of a line but not at the beginning of the following line.
It works ok here. There's a well-known problem with string gaps in conjunction with CPP; see http://www.haskell.org/ghc/docs/latest/set/options-phases.html#C-PRE-PROCESS... If this isn't the problem, could you send us a complete module which fails to compile? Cheers, Simon