| SPECIALISE pragmas are not supported in any but the defining module | because the Core for a function to specialise is not guaranteed to be | available in any other module. I don't think there is any other | barrier. Yes, exactly. | It is possible to imagine implementing a remedy for this by using | -fexpose-all-unfoldings and having GHC use the exposed Core to | generate a specialisation in any importing module. Indeed, I've often thought of such a feature. It would be a Good Thing. But some care would be needed. Currently GHC's "-fexpose-all-unfoldings" makes no attempt to ensure that the exposed unfolding for f is exactly what the user originally wrote. For example, other functions might have been inlined into f's RHS that might make it a lot bigger. Maybe you'd want to say {-# SPECIALISABLE f #-} f = <blah> to mean "expose f's unfolding, pretty much as-is, rather than optimising it". This is close to what you get with {-# INLINE f #-} (which also exposes the original RHS) but without the "please inline me at every call site" meaning. Hmm. Oh if I had more time. But as of today, no it just isn't supported. Another ticket! http://hackage.haskell.org/trac/ghc/ticket/4227 Simon