Editing Maclisp (section)

==Characteristics==
Maclisp began with a small, fixed number of [[data type]]s: [[cons]] cell, atom (later termed ''symbol''), [[integer]], and [[Floating-point arithmetic|floating-point number]].  Later additions included: [[Array data type|arrays]], which were never first-class data types; [[Arbitrary-precision arithmetic|arbitrary-precision integers]] (bignums); [[String (computer science)|strings]]; and [[tuple]]s.  All objects (except inums) were implemented as [[Pointer (computer programming)|pointers]], and their data type was determined by the block of memory into which it pointed, with a special case for small numbers (inums).

Programs could be ''[[Interpreted language|interpreted]]'' or ''[[Compiler|compiled]]''.  Compiled behavior was the same as interpreted except that local variables were lexical by default in compiled code, unless declared SPECIAL,<ref>{{cite web |url=http://maclisp.info/pitmanual/complr.html#23.1.2 |title=The Revised Maclisp Manual (The Pitmanual), Sunday Morning Edition |last=Pitman |first=Kent |date=December 16, 2007 |website=maclisp.info |publisher=HyperMeta, Inc. |access-date=October 20, 2018 |at=Declarations and the Compiler, Concept "Variables" |quote= If the variable to be bound has been declared to be special, the binding is compiled as code to imitate the way the interpreter binds variables.}}</ref> and no error checking was done for inline operations such as CAR and CDR.  The Ncomplr compiler (mid-1970s) introduced fast numeric support to Lisp languages, generating [[machine code]] (instructions) for arithmetic rather than calling interpretive routines which dispatched on data type.  This made Lisp arithmetic comparable in speed to [[Fortran]] for scalar operations (though Fortran array and loop implementation remained much faster).

The original version was limited by the 18-bit word [[memory address]] of the PDP-10, and considerable effort was expended in keeping the implementation lean and simple. Multics Maclisp had a far larger address space, but was costly to use.  When the memory and processing power of the [[PDP-10]] were exceeded, the [[Lisp Machine]] was invented: [[Lisp Machine Lisp]] is the direct descendant of Maclisp.  Several other [[Lisp (programming language)|Lisp]] dialects were also in use, and the need to unify the community resulted in the modern [[Common Lisp]] language.