Wolfgang Jeltsch
Am Dienstag, 6. April 2004 20:13 schrieb Isaac Jones:
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(d) For those differences that cannot be eliminated implementing (in Haskell) a portable preprocessor that can ship as part of every Haskell environment?
I think this is ultimately going to be the most viable solution. Let's write a simple 'hspp' (in Haskell?) that is backward compatible with 'cpp -traditional' (although we might also design a newer nicer syntax too), and distribute it with every compiler. It can't be too difficult, surely? Half of the cpp parsing/selection code is already available within hmake. I would take on the project myself, if I had time.
I agree that this should be possible with the hmake code. FWIW, I have, in fact, already teased that functionality out (to a small degree) and made it available in my work-in-progress HMake API.
Will such a preprocessor work on source code like cpp does or on a syntax tree?
On source code, at least for now. There's no plan, ATM, to include a parser with Distribution.Build. It could be useful, but I expect that we want to pass such work onto the compilers / interpreters. Can you explain the syntax tree you picture for this? Where will such a tree come from?
The latter would be better,
Why?
IMO; the former would probably have little or no advantage over cpp.
From the point of view of this conversation, the advantage would be that it's implemented in pure Haskell, so you don't need external tools that may be difficult to get on your system.
The reason it's there in Distribution.Build is so that wrapper build systems (whether they be implemented in Make or in Haskell) can utilize a common interface. peace, isaac