[pitaj]

That's a bad example, as it has really nothing to do with types, but instead the semantics of the coercion-implicit equality operator (==) vs the strict equality operator (===). Javascript has types, they are just dynamic, tied to values, not variables.

[edejong]

I don't think it's such a bad example. In a strongly typed language, it would be relatively difficult to 'type' the '==' operator which would be reflected by its horrific signature. The '===' operator, especially in language supporting type classes, would instead be relatively easy to define. The type indicates whether a concept, which might seem simple, is complex.

However, where static languages are lacking is in supplying proof of the rules associated with these operators. In the case of equality, that would be associativity, reflexivity and transitivity.