Alex Jacobson wrote:
Isn't use of the extensions detectable by the compiler?
Not always, no. Some extensions modify the syntax, such that programs accepted with the extension turned on are not necessarily a superset of those accepted with the extension turned off. For example: MagicHash (modifies the meaning of a # suffix on an identifier), RankNTypes (steals 'forall' and '.' from the type-variable namespace), etc. Cheers, Simon
If so, then forcing the user manually to enumerate them at the top of a source file seems like forcing the user to write a lot of unnecessary boilerplate. It seems preferable for the compiler ny default just to issue warnings about what extensions are used. Then the person doing the compiling can decide to modify code not to use those features, to add pragmas so as not to cause warning, or to add compiler flags that tells it not to issue them.
In any case, I'm pretty sure the correct answer is not 50 language pragmas with arbitrary spellings for various language features at the top of each source file.
-Alex-
Simon Marlow wrote:
Alex Jacobson wrote:
I'm fine with that as well. I'm just opposed to being force to look up the precise names the compiler happens to use for each language extension I happen to use. Having -fglasgow-exts turned on by default also works.
-fglasgow-exts is a historical relic. It's just an arbitrary collection of extensions. It doesn't contain all the extensions provided by GHC, as many of them steal syntax and you probably don't want them all on at the same time. We're trying to move away from -fglasgow-exts, which is why GHC 6.8.1 provides separate flags for all the extensions we provide. Eventually we'll have a new standard (Haskell' or whatever) that will collect many of the extensions together, so you'll just have to write {-# LANGUAGE Haskell' #-}.
Cheers, Simon _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users