[Haskell-cafe] Re: [Haskell] Does GHC support the standard CPP functionalities?

[Malcolm Wallace]

[moved to haskell-cafe]

> {-# LANGUAGE CPP #-}
>
> module Packer where
>
> #define FLASH_APP_START  1
> #define FLASH_APP_END    2
> #define INSERT_SECTION(x) (#x, (FLASH_##x##_START, FLASH_##x##_END))

The CPP stringization operator # and the token-catenation operator ##  
are ANSI additions over the traditional K+R CPP.  Ghc uses the - 
traditional flag to exclude them, because both # and ## are valid  
Haskell operators, and most people would not want them to be removed  
by the CPP preprocessor.

There are also some other lexical differences between Haskell and C  
which make it a good ides for ghc to use cpp -traditional.

However, if you really want to use ANSI additions, you can switch to  
cpphs,
which does know about the lexical syntax of Haskell.
     http://haskell.org/cpphs
To use it with ghc, you will need to pass the following extra options:
     ghc -cpp -pgmPcpphs -optP--cpp -optP-ansi

Unfortunately, I'm not certain I can guarantee that the -ansi flag  
will take effect - it depends on whether ghc internally adds the - 
traditional argument before or after it.

Regards,
     Malcolm