libdwarf reads and/or writes DWARF debugging information in Elf object files. dwarfdump uses libdwarf to read object files and print the DWARF content in a readable fashion. libdwarf implements the DWARF2 (and later) standard by providing function interfaces that abstract away many DWARF implementation details (the writer code only emits DWARF2 so far). The source also includes implementations of a few tree search (tsearch) algorithms (balanced, red-black, and binary).
HGL is a compiler/interpreter suite for developing images. It features its own simple but powerful language, Lua integration, output in various formats as well as runtime input handled by plugins, and easy integration into various environments like Web servers or graphical applications. The input is taken from a source file, which has to be compiled for quick and frequent access by the interpreter. An interpreter then runs the compiled files, takes input from custom plugins (if neccessary), and outputs its result via custom plugins.
J2ObjC is a tool from Google that translates Java code to Objective-C for the iOS platform. It enables Java code to be part of an iOS build, as no editing of the generated files is necessary. The goal is to write an app's non-UI code (such as data access or application logic) in Java, which can then be shared by Web apps using GWT, Android apps, and iOS apps. J2ObjC supports most Java language and runtime features required by client-side application developers, including exceptions, inner and anonymous classes, generic types, threads, and reflection. JUnit test translation and execution are also supported.
foma is a compiler, programming language, and C library for constructing finite-state automata and transducers for various uses. It has specific support for many natural language processing applications such as producing morphological analyzers. Although NLP applications are probably the main use of foma, it is sufficiently generic to use for a large number of purposes. It comes with an xfst-compatible interface and regular expression language. The library contains efficient implementations of all classical automata/transducer algorithms: determinization, minimization, epsilon-removal, composition, and boolean operations. More advanced construction methods are also available: context restriction, quotients, first-order regular logic, transducers from replacement rules, etc.
GCC-MELT is a high-level domain specific language that eases the development of plugin-like extensions for GCC, the Gnu Compiler Collection. These extensions can analyze or modify GCC internal representations, and can be used for static source code analysis, refactoring, specific warnings, optimizations, etc. The MELT language provides high-level features. Notably, MELT code is translated to C or C++, and can even contain C or C++ code. It includes powerful pattern matching facilities and can manipulate dynamically typed values and raw GCC structures. It enables functional/applicative, object-oriented, reflective programming styles and has a familiar Lisp-like syntax.