Am Donnerstag, 22. November 2007 02:07 schrieb Alex Jacobson:
Duncan Coutts wrote:
On Wed, 2007-11-21 at 19:26 -0500, Alex Jacobson wrote:
Ok, I'm game to default to haskell98 in the presence of ambiguity, but in most cases the extension involves new syntax and that should be enough.
In these cases ghc does generally give an error message which mentions which extension it is that you should use. This is actually better than the case where you forget to import something when ghc doesn't helpfully tell you which module you forgot to import.
My point is that the default should be to give a warning rather than an error and provide the user with the ability to turn those warnings off.
As others have said, one major reason for declaring extensions is for portability.
The warning should be enough information for people who want to avoid accidentally adding features that will cause their code not to run on other compilers. For those that don't care, forcing them to add zillions of pragmas is an excessive burden.
-Alex-
Dont’t just think in terms of single modules. If I have a Cabal package, I can declare used extensions in the Cabal file. A user can decide not to start building at all if he/she sees that the package uses an extension unsupported by the compiler. Best wishes, Wolfgang