Editing MLisp (section)

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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 programming language|Lisp]] with an [[ALGOL|Algol]]-like syntax based on [[M-expression|M-Expressions]], which were the function syntax in the original description of Lisp by [[John McCarthy (computer scientist)|John McCarthy]].  McCarthy's M-expressions were never implemented in an exact form.<ref>Enea, Horace (1968) MLISP [http://i.stanford.edu/TR/CS-TR-68-92.html ''CS-TR-68-92.pdf'']</ref>

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|FEXPR]]"), which do not evaluate their arguments.<!-- Could this be used to implement lazy evaluation? -->  As in [[Lisp (programming language)|Lisp-1]] or [[Scheme (programming language)|Scheme]], there was a single namespace for variables and functions.<ref>Smith, David Canfield (1970) MLISP USERS' MANUAL [https://www.saildart.org/AIM/084/pdf ''Smith-MLISP-AIM-84.pdf''] (recommended first)</ref>

While MLISP was just a preprocessor with an alternative, more reader-friendly syntax for Lisp, the descendant '''MLISP 2''' introduced new concepts:<ref>Smith, David Canfield and Enea, Horace J. (1973) MLISP 2 [http://i.stanford.edu/TR/CS-TR-73-356.html ''CS-TR-73-356.pdf'']</ref>

* interactive interpretation of programs instead of compilation
* extensibility with a syntax description language (see [[hygienic macro]]s)
* [[pattern matching]]
* [[backtracking]] by the use of [[Closure (computer science)|closure]]s on a stack and indices for [[continuation]]s<ref>Smith, David Canfield and Enea, Horace J. (1973) Backtracking in MLISP2: an efficient backtracking method for LISP [https://www.ijcai.org/Proceedings/73/Papers/074.pdf ''074.pdf'']</ref>

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 (programming language)|ML]] or Scheme.<ref>Tesler, Lawrence G., Smith, David Canfield and Enea, Horace J. (1973) The LISP70 pattern matching system [https://www.ijcai.org/Proceedings/73/Papers/073.pdf ''073.pdf'']</ref>

'''M-LISP''' (MetaLISP) by Robert Muller is an unrelated language from 1989–1992. It was "a hybrid of [[M-expression]] LISP and [[Scheme (programming language)|Scheme]]".<ref>{{cite journal |last1=Muller |first1=Robert |title=M-LISP: a representation-independent dialect of LISP with reduction semantics |journal=ACM Transactions on Programming Languages and Systems |date=October 1992 |volume=14 |issue=4 |pages=589–616 |doi=10.1145/133233.133254 |doi-access=free |citeseerx=10.1.1.40.4948}}</ref><ref>{{cite thesis |last1=Muller |first1=Robert |title=MetaLISP: a representation independent dialect of LISP with reduction semantics |type=PhD thesis |date=1989}}</ref>