if you mean inferring types from un-annotated programs, it has been tried a couple of times - if you search around you can find other people's attempts (i think

if you mean inferring types from un-annotated programs, it has been tried a couple of times - if you search around you can find other people's attempts (i think there is a thesis and a dead project on the net). [To answer your question; I think it would be useful (I once started work on something similar myself, but never got to actually unifying types). However, the fact that other people have tried and failed to be come popular suggests that there are (more) problems (than you might expect).]