"Simon Marlow" writes:

...

GHC actually has rather sophisticated recompilation checking which goes beyond just checking whether the interface changed - it keeps version information for each entity exported by a module and only recompiles if any of the entities actually used by the module have changed (this is described in the user's guide under the section on recompilation checking).

So the upshot is that what you're describing shouldn't happen, and it may be a bug. Could you send us more info?

Note that in GHC, the "version number" of a function can often change for hard-to-spot reasons. You just need to change (for example) the strictness properties of the function, which can be very easy to do when making changes to your code. The compiler cares about (much) more than just the types of imported objects. I tend to expect recompiles whenever something depends on a function I've changed, even if I don't think the changes were very significant.

Good point. But I'd also like to add that these hard-to-spot reasons only apply when optimisation is turned on - otherwise the only way a function's version number may change is if its type changes. In GHCi, optimisation is never on so you shouldn't see any of these effects. Cheers, Simon