PLT Scheme is a programming language suitable for implementation tasks ranging from scripting to application development, including GUIs, Web services, etc. It includes the DrScheme programming environment, a virtual machine with a just-in-time compiler, tools for creating stand-alone executables, the PLT Scheme Web server, extensive libraries, documentation for both beginners and experts, and more. It supports the creation of new programming languages through a rich,expressive syntax system. Example languages include Typed Scheme, ACL2, FrTime, Lazy Scheme, and ProfessorJ (which is a pedagogical dialect of Java). License: GNU Lesser General Public License (LGPL) Changes:
In DrScheme, the Module language automatically inserts a "#lang" line so that the repl is always working. Interactive search was added. Memory limits are on. Typed Scheme supports a mechanism for variable-arity function definitions and applications. Redex is now included. Many documentation improvements were made, such as better searching, table-of-contents, and language-sensitive help. The world.ss teachpack no longer supports "end-of-time", only "stop-when". MzScheme has a logging facility, called "logger". "begin" in R5RS and "#lang planet" were fixed. "eval" now works with phases.

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