If the switches take affect at the line granularity there would seem to be a straightforward implementation that's orthogonal to most everything else: store the excluded regions in separate data structure and check that data structure before printing a message. mike

...

GHC's excellent warnings are very helpful. They would be somewhat more so if it were possible to suppress a warning about a specific bit of code. One possible syntax (to which I gave no commitment) would be

{-# WOFF "non-exhaustive pattern matches" #-} <offending code> {-# WON "non-exhaustive pattern matches" #-}

. Another would be

{-# WOFF 523 #-} <offending code> {-# WON 523 #-}

where 523 is a warning number emitted with the warning message.

This would be particularly useful with the recently granted wish for -Werror.

This would be nice, but it would be tricky to implement: declarations have to be tagged with a list of "exceptions" to the prevailing warning settings. I doubt we'll do this any time soon, but patches are welcome as usual...

(of course, the workaround is to put the offending code into a module of its own, and use OPTIONS to turn off the appropriate warnings).

Cheers, SImon