By static typing, I meant compile-time type checking, and statically-typed compilation. You describe run-time type checking in dynamically-typed compiled code which was in Groovy (without generics) from the beginning but makes the code run even slower than the already slow dynamically-typed compiled code without such run-time type checking. Run-time type checking with generics was added to Groovy from version 1.5.

Perhaps I should've used the expressions "compile-time ..." and "run-time ..." to be more accurate, but virtually everyone uses "statically-typed" and "dynamically-typed" in their place.

The other poster is right. That is typing, that is not static type checking.

You can write code like:

List<MyObject> mylist = new HashSet<Integer>() {{ add("string"); add(1L); }}

You will get groovy.lang.GroovyRuntimeException with constructor issues.