patch applied (haskell-prime-status): proposal: remove string gaps

Henrik Nilsson nhn at Cs.Nott.AC.UK
Wed Apr 2 04:46:19 EDT 2008

Hi Neil,

 > >  Well, for the record, I've used both CPP and string gaps
 > >  extensively. And all I've done is to be careful to run CPP
 > >  only where needed (and avoid string gaps there), which seems
 > >  rather sensible to me anyway, string gaps or not.
 > Having two "features" which can't be used together in the same file
 > seems ridiculous.

Again, CPP is not part of Haskell as such, and I hope it won't become
part either. So anyone using CPP with Haskel should know what
they are doing. True, it so happens that CPP does get use a fair
bit with Haskell for various reasons, and there is some dedicated
tool support for CPP. So it would be good if the version of CPP
used through a Haskell tool chain was Haskell aware.

 > It gets much worse if you decide "ghc --make -cpp"
 > is the way you want to build your application, as we used to do for
 > Yhc.


    {-# LANGUAGE CPP #-}

be a viable option in the, presumably rather few, files where CPP
really is used? (That's also rather good documentation for the
reader of the file, incidentally.)

Again, running an entire project through CPP just because a few
files needs CPP-ing, is something I at least would try to avoid.

 > I suggest that if string gaps don't get removed, then GHC should
 > fix its -cpp flag.

Would be nice, but probably not an H' discussion topic, unless
you're arguing that some kind of CPP facility is mandated by the
H' standard?



Henrik Nilsson
School of Computer Science
The University of Nottingham
nhn at

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