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

[John Lask]

indeed it was the cpp, and the behaviour is consistent beetween versions, I 
must have introduced some changes that affected the eol marker. Thanks for 
your tip.

jvl

----- Original Message ----- 
From: "Duncan Coutts" <duncan.coutts at worc.ox.ac.uk>
To: "John Lask" <jvlask at hotmail.com>
Cc: <glasgow-haskell-users at haskell.org>
Sent: Sunday, August 23, 2009 12:34 AM
Subject: Re: ghc 6.10.4 infix declarations and '\' bug or not ?


> 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
>
>