Detail #86: Interaction between the case system and the verb

Let us consider a language that uses the dative  to mark direction towards, and say, any one out of {genitive, accusative, partitive, locative} to mark location.

Let us also consider a verb system in place in the same language, where some kind of aspect distinction is made. For convenience, we call them imperfect and perfect. Whether it really is perfectivity, perfectness, telicity or something else is not that important, as long as it is something along those lines.

Now, let us imagine how this language will express location or direction: I find it pretty likely that direction and location merge in perfect contexts, or rather, direction is considered meaningless in the perfective, or at the very least sufficiently less meaningful to warrant a naked caseform marking it.

I go.perf town.dat = I am/was in town
I go.impf town.dat = I am heading towards town
I go.impf town.[the other case] = I walk in town

Thus, the dative alternates between locative and directional depending on the aspect of the verb.