MDL (programming language): Difference between revisions

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'''MDL''' (the MIT Design Language) is a descendant of the [[Lisp programming language|Lisp]] [[Programming]] language. Its initial purpose was to provide high level language support for the Dynamic Modeling Group at [[Massachusetts Institute of Technology|MIT]]'s [[Project MAC]]. It was initially developed in 1971 on the [[PDP-10]] computer under the [[Incompatible Timesharing System]] .

The initial development team consisted of [[Gerald Sussman]] and [[Carl Hewitt]] of the Artificial Intelligence Lab, and Chris Reeve, Bruce Daniels, and David Cressey of the Dynamic Modeling Group. Later, Stu Galley, also of the Dynamic Modeling Group, wrote the MDL documentation.

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.