Mup produces very high quality PostScript printed music or a MIDI file from a text input file. It can handle almost any kind of music, instrumental or vocal, including tablature, shaped notes, guitar grids, alternate tunings, user-defined symbols, and much more. Mup has been under active development since 1992.
Factor is a dynamically-typed stack-based programming language. Factor runs on various OSes and CPU architectures, and provides an optimizing compiler, interactive development environment, powerful collections, higher order programming, continuations, and a growing library of contributed code.
Nemerle is a hybrid (functional, object-oriented and imperative) programming language for the .NET platform. The key features of the language include C#-like syntax, easy access to functional, object-oriented, and imperative features, powerful code-generating macros, variants, pattern matching, static and on-demand dynamic typing, and type inference.
LibGC is a small, fast, portable, multi-threaded garbage collection library for C++. It is highly customizable, as it can be multithreaded or single threaded, and the memory size to use for the collector may be changed at compile time. It is precise, as it only scans pointers that exist as members on the stack or as global variables. It's very easy to use, since it has only two classes, Object (the base class for garbage-collected objects) and Pointer (for garbage-collected pointers).