Type Inference vs. Static/Dynamic Typing (opens in new tab)

Eh? I'm not disputing that at all, I'm a contributor to PyPy, probably the leading python JIT. None of that has anything to do with whether it's semantically possible to do a full type inference on a language like Python.

Here's a link to the relevant section: http://www.sbcl.org/manual/#Declarations-as-Assertions

Scala does that because ad hoc polymorphism doesnt resolve well with hindley milner type inference. F# also has this limitation and they get some of the way around this with a strict vertical projects file layout. The scope of its type inference is a middle ground between Scala and Ocaml which I think is a nice optimum, you leave most things untyped except the overloads which can't be determined so that the eager generalization you encounter in ocaml is less of a problem there too. The price in project layout is quite steep though but like in all things you train your self around it.

Plus with an IDE in Scala (or F#) you can just hover for the types.

I find it very difficult to believe that a large source of errors in ML programs are caused by programmers forgetting to annotate type information on top level functions.