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MLisp

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"MLisp" is also another name for Mocklisp, a stripped-down version of Lisp used as an extension language in Gosling Emacs.

MLISP is a variant of Lisp with an Algol-like syntax based on M-Expressions, which were the function syntax in the original description of Lisp by John McCarthy. McCarthy's M-expressions were never implemented in an exact form.cite-ref-1[1]

MLISP was first implemented for the IBM 360 by Horace Enea and then reimplemented for the PDP 10 by David Canfield Smith. This second implementation also supported a special kind of lambdas ("FEXPR"), which do not evaluate their arguments. As in Lisp-1 or Scheme, there was a single namespace for variables and functions.cite-ref-2[2]

While MLISP was just a preprocessor with an alternative, more reader-friendly syntax for Lisp, the descendant MLISP 2 introduced new concepts:cite-ref-3[3]

• interactive interpretation of programs instead of compilation

• extensibility with a syntax description language (see hygienic macros)

• pattern matching

• backtracking by the use of closures on a stack and indices for continuationscite-ref-4[4]

MLISP2 was called a transitional language by the authors. Larry Tesler improved the pattern matching system to implement a successor language called LISP70, which was only completed to a preliminary version. Though this path of LISP evolution is widely neglected, it resembles some features, later found in ML or Scheme.cite-ref-5[5]

M-LISP (MetaLISP) by Robert Muller is an unrelated language from 1989–1992. It was "a hybrid of M-expression LISP and Scheme".cite-ref-6[6]cite-ref-7[7]

Contents

• See also

• References