HGL is a compiler/interpreter suite for developing images. It features its own simple but powerful language, an output format configurable by plugins, 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.
AI::Prolog is a predicate logic engine implemented in pure Perl. In predicate logic, instead of telling the computer how to do something, you tell the computer what something is and let it figure out how to do it. Conceptually, this is similar to regular expressions. The AI::Prolog distribution contains a Prolog shell called aiprolog and two short adventure games, spider.pro and sleepy.pro.
The Tcl extension provides a small but complete interface into libtcl and any other Tcl-based library for Perl programmers. It lets you create Tcl interpreters (as Perl 5 objects), bind in commands to them (either Perl subroutines or C functions dynamically loaded with the DynaLoader extension), and execute Tcl code in those interpreters.