This doesn't match with my experience. Julia is really excellent at infering complicated types. What you might be running into is type ambiguity though where Ju

This doesn't match with my experience. Julia is really excellent at infering complicated types. What you might be running into is type ambiguity though where Julia has to resort to unions because that's what the loops needs to work. Have a look at @code_warntype of some function call to see if that is the problem.