The Glasgow Haskell Compiler is a robust, fully-featured, optimising compiler for the functional programming language Haskell. GHC compiles Haskell to either native code or C. It implements numerous experimental language extensions to Haskell for example concurrency, a foreign language interface, several type-system extensions, exceptions, and so on. GHC comes with a generational garbage collector, a space and time profiler, and a comprehensive set of libraries.
A practical lambda-calculator is a normal-order evaluator for the untyped lambda-calculus, extended with convenient commands and shortcuts to make programming in it more productive. Shortcuts are distinguished constants that represent terms. Commands define new shortcuts, activate tracing of all reductions, compare terms modulo alpha-conversion, print all defined shortcuts and evaluation flags, etc. Terms to evaluate and commands are entered at a read-eval-print-loop (REPL) "prompt" or "included" from a file by a special command. A Haskell branch is an embedding of the lambda calculator (as a domain-specific language) into Haskell. The calculator can be used interactively within Hugs or GHCi.
Xcerpt is a declarative, rule-based query and transformation language for XML, inspired by logic programming. Instead of the path-based navigational approach taken by languages like XSLT and XQuery, Xcerpt uses pattern-based, positional queries, where a pattern is an "example" of the database containing variables for binding content. As in logic programming, rules may be chained to form more complex queries.