ghc 6.10.4 infix declarations and '\' bug or not ?

[Duncan Coutts]

On Sat, 2009-08-22 at 15:52 +1000, John Lask wrote:
> in declaring fixity for an operator (\\) to get it to compile using ghc 
> 6.10.4, I needed to use the following code
> 
> infixl 9 \\\
> (\\) a b = etc ...
> 
> where I assume the first \ escapes the second \, using infixl 9 \\ generates 
> a syntax error
>
> infixl 9 \\  used to compile no problems with ghc 6.8.2
> 
> what is going on here ?

Usually this problem is related to cpp, since \\ at the end of a line
has special meaning to cpp.

Are you sure that you're comparing like with like when you say it worked
in ghc-6.8.2? If you're using cpp for the module now and in the past you
were not then that would explain it.

Another trick I've seen is:

infixl 9 \\  -- this comment is here to defeat evil cpp mangling

Duncan