Re: #s causing errors when -cpp not given
On Mon, Jan 28, 2002 at 05:25:29PM -, Simon Marlow wrote:
You're right, it seems that our 'unlit' program (the filter used to
convert a literate file into an illiterate one) leaves lines beginning
with '#' in place.
We could remove this, but I'm not sure how much code it would break. We
As far as I can think the only code which should break is code like
this:
module Main where
(#) = (++)
main = putStrLn x
where { x = foo
# bar #
baz }
(which in GHC prints foobarbaz) which deserves to be broken IMO!
could also do this conditionally based on a flag to unlit which would be
turned on if we're planning to CPP the file, but there's another
problem: sometimes we use {-#OPTIONS -cpp#-} at the top of the file to
indicate that cpp is to be used, so we don't know whether we're going to
be cpp'ing until after we've unlitted the file :-(
I would advocate only allowing #s where code is allowed, but I fear that
ship has sailed :-(
It would also be less simple with being replaced by a space rather
than removed.
Ian
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RE: #s causing errors when -cpp not given
I've just been looking at using cpp in Haskell scripts and I am rather
confused. I can't see anything in the report which gives
special meaning
to # in the surrounding text of literate scripts, yet if I put such
things in (both cpp directives and random things) both nhc98 and ghc
give me errors:
$ rm Foo.{o,hi}; nhc98 -c Foo.lhs -o Foo.o
Unknown preprocessor directive at line 4 in file ./Foo.lhs
ifdef QQ
$ rm Foo.{o,hi}; ghc -c Foo.lhs -o Foo.o
Foo.lhs:4: parse error on input `#'
Are ghc and nhc98 being incompatible with Haskell 98?
GHC has one small extension to Haskell 98 in this area: the lexical
analyser interprets directives line '# 99 Foo.hs' at the beginning of
a line in order to get line number and file clues when it is parsing the
output from CPP. Apart from this, '#' should be interpreted exactly as
per the report (when -fglasgow-exts is off).
Could you send us the source?
Cheers,
Simon
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