Hugs with C preprocessor

[Wolfgang Jeltsch]

Am Mittwoch, 7. Januar 2004 20:37 schrieb Alastair Reid:
> > I want to use Haskell files with #ifdef, #else and #endif preprocessor
> > directives.  I tried hugs -F "cpp -P" <source_file_name> but cpp
> > complains about unterminated character constants.  What is wrong?
>
> ANSI C preprocessors tend to get confused by the quotes in lines like the
> following:
>
>    f x = x' where x' = ...
>    g x = x'
>      where
>       x' = ...
>
> You can often avoid this by putting cpp in 'K&R mode'. For example, GNU cpp
> accepts '-traditional'.

I tried hugs -F "cpp -P -traditional" but got the same error message as 
without -traditional. This message is, suprisingly,
    sh: line 1: /usr/lib/hugs/libraries/Hugs/Prelude.hs: Permission denied
    ERROR "/usr/lib/hugs/libraries/Hugs/Prelude.hs" - Module "case"
    recursively imports itself

    FATAL ERROR: Unable to load Prelude.

I started hugs without the -F option and then tried to set it via :set -F"cpp 
-P -traditional".  After this I loaded my input file via :load and got these 
messages:
    cpp0: output pipe has been closed
    cpp0: output pipe has been closed
    cpp0: output pipe has been closed
    cpp0: output pipe has been closed
    cpp0: output pipe has been closed
    cpp0: output pipe has been closed
    cpp0: output pipe has been closed
    cpp0: output pipe has been closed
    cpp0: output pipe has been closed
    ERROR "./RegAlloc/Data/Graphs.hs":42 - Syntax error in input (unexpected
    selector "#ifdef")
So cpp gives strange error messages and #ifdefs still don't work.

> I'm attaching a shell script you might use (from end of hugs98/Install in
> the Hugs98 distribution).  (Not tested recently but ought to work.)

> [...]

>           if $running_under_some_random_shell;

Is this real code?

> [...]

>      # Reads CPP output and turns #line things into appropriate Haskell
>      # pragmas.  This program is derived from the "hscpp" script
>      # distributed with the Glasgow Haskell Compiler.

I already looked for hscpp but it doesn't seem to be included in 6.2.  Is it 
still in use with GHC?

> [...]

Wolfgang