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.^[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.^[2]

While MLISP was just a preprocessor with an alternative, more reader-friendly syntax for Lisp, the descendant MLISP 2 introduced new concepts:^[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 continuations^[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.^[5]

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

See also

There have been multiple implementations of infix-notation Lisps and Lisp-like or Lisp-derived languages. Some notable examples include:

• Dylan, which originated in Apple's Newton project
• CGOL

References