> GCL is a whole nasty programming language. They came so close with Piccolo and Gmon but still made it not Python.

The GCL designers made several mistakes in its design, but the worse was the lack of a versioning that would make language evolution easier, as well as interoperability between different versions. GCL2 solved some issues, mainly cleaning up the interpreter. Still, BCL is IMNSHO by far the best infra language there is.