| However, whenever I change a data type or class even if they are not | exported, it seems to force a full rebuild of everything that depends on | that file. Is there any fundamental reason this can't be fixed? why do | the non exported classes and data types end up in the hi file anyway | (assuming they appear in no exported functions type signature of course) There's no fundamental reason. I think I just thought that it'd be seldom for a data type or class to be defined only internally to a module, and not exported at all. Somewhat more common is for the *implementation* of the data type (i.e. its data constructors) to be internal, but the type itself is exported. So then one would want to have a partial spec in the interface file, giving the kind but not the constructors. Again, I didn’t work on this case. I'll add a Trac feature request, so we don't forget this Simon