OpenPoplog is a multi-language, incrementally-compiled virtual machine-based development environment with its own extensive teaching and support material, supporting the languages Pop-11, Prolog, Common Lisp and ML on Unix, VMS, Linux and Windows.
Parallel Events and Asynchronous tasKing Library. Originally combining multi-threading with an efficient I/O event model, it's now more a lightweight object-oriented framework for event-based applications.