MDL (programming language): Difference between revisions

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Revision as of 18:01, 11 January 2013

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MDL was initially known as “Muddle”. This style of self-deprecating humor was not widely understood or appreciated outside of Project MAC and a few other early citadels of information technology. So the name was sanitized to MDL.

MDL provides several enhancements to classical Lisp. It supports several built-in data types, including lists, strings and arrays, and also user-defined data types. It offers multithreaded expression evaluation and coroutines. Variables can carry both a local value within a scope, and a global value, for passing data between scopes. Advanced built-in functions supported interactive debugging of MDL programs, incremental development, and reconstruction of source programs from object programs.

Although MDL is obsolete, some of its features have been incorporated in later versions of Lisp. Gerald Sussman went on to develop the [[Scheme (programming language)|Scheme]] language, in collaboration with [[Guy Steele]], who later wrote the specifications for [[Common Lisp]] and [[Java (programming language)|Java]]. Carl Hewitt had already published the idea for the [[PLANNER]] language before the MDL project began, but his subsequent thinking on PLANNER reflected lessons learned from building MDL. Planner concepts influenced languages such as [[Prolog]] and [[Smalltalk]]. Smalltalk and [[Simula]], in turn, influenced his future work on the [[Actor model]].