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lambda combinationn.Trad. alambda form.

lambda expressionn. alist which can be used in place of afunction name in certain contexts to denote afunction by directly describing its behavior rather than indirectly by referring to the name of anestablishedfunction; its name derives from the fact that its first element is thesymbollambda. Seelambda.

lambda formn. aform that is alist and that has a first element which is alambda expression representing afunction to be called onarguments which are the result ofevaluating subsequent elements of thelambda form.

lambda listn. alist that specifies a set ofparameters (sometimes calledlambda variables) and a protocol for receivingvalues for thoseparameters; that is, anordinary lambda list, anextended lambda list, or amodified lambda list.

lambda list keywordn. asymbol whosename begins withampersand and that is specially recognized in alambda list. Note that nostandardizedlambda list keyword is in theKEYWORD package.

lambda variablen. aformal parameter, used to emphasize thevariable's relation to thelambda list thatestablished it.

leafn. 1. anatom in atree[1]. 2. a terminal node of atree[2].

leap secondsn. additional one-second intervals of time that are occasionally inserted into the true calendar by official timekeepers as a correction similar to ``leap years.'' All Common Lisptime representations ignoreleap seconds; every day is assumed to be exactly 86400 seconds long.

left-parenthesisn. thestandard character ``('', that is variously called ``left parenthesis'' or ``open parenthesis'' SeeFigure 2-5.

lengthn. (of asequence) the number ofelements in thesequence. (Note that if thesequence is avector with afill pointer, itslength is the same as thefill pointer even though the total allocated size of thevector might be larger.)

lexical bindingn. abinding in alexical environment.

lexical closuren. afunction that, when invoked onarguments, executes the body of alambda expression in thelexical environment that was captured at the time of the creation of thelexical closure, augmented bybindings of thefunction'sparameters to the correspondingarguments.

lexical environmentn. that part of theenvironment that containsbindings whose names havelexical scope. Alexical environment contains, among other things: ordinarybindings ofvariablenames tovalues, lexicallyestablishedbindings offunction names tofunctions,macros,symbol macros,blocks,tags, andlocal declarations (seedeclare).

lexical scopen.scope that is limited to a spatial or textual region within the establishingform. ``The names of parameters to a function normally are lexically scoped.''

lexical variablen. avariable thebinding for which is in thelexical environment.

Lisp imagen. a running instantiation of a Common Lispimplementation. ALisp image is characterized by a single address space in which anyobject can directly refer to any another in conformance with this specification, and by a single, common,global environment. (External operating systems sometimes call this a ``core image,'' ``fork,'' ``incarnation,'' ``job,'' or ``process.'' Note however, that the issue of a ``process'' in such an operating system is technically orthogonal to the issue of aLisp image being defined here. Depending on the operating system, a single ``process'' might have multipleLisp images, and multiple ``processes'' might reside in a singleLisp image. Hence, it is the idea of a fully shared address space for direct reference among allobjects which is the defining characteristic. Note, too, that two ``processes'' which have a communication area that permits the sharing of some but not allobjects are considered to be distinctLisp images.)

Lisp printern.Trad. the procedure that prints the character representation of anobject onto astream. (This procedure is implemented by thefunctionwrite.)

Lisp read-eval-print loopn.Trad. an endless loop thatreads[2] aform,evaluates it, and prints (i.e.,writes[2]) the results. In manyimplementations, the default mode of interaction with Common Lisp during program development is through such a loop.

Lisp readern.Trad. the procedure that parses character representations ofobjects from astream, producingobjects. (This procedure is implemented by thefunctionread.)

listn. 1. a chain ofconses in which thecar of eachcons is anelement of thelist, and thecdr of eachcons is either the next link in the chain or a terminatingatom. See alsoproper list,dotted list, orcircular list. 2. thetype that is the union ofnull andcons.

list designatorn. adesignator for alist ofobjects; that is, anobject that denotes alist and that is one of: anon-nilatom (denoting asingletonlist whoseelement is thatnon-nilatom) or aproper list (denoting itself).

list structuren. (of alist) the set ofconses that make up thelist. Note that while thecar[1b] component of each suchcons is part of thelist structure, theobjects that areelements of thelist (i.e., theobjects that are thecars[2] of eachcons in thelist) are not themselves part of itslist structure, even if they areconses, except in the (circular[2]) case where thelist actually contains one of itstails as anelement. (Thelist structure of alist is sometimes redundantly referred to as its ``top-level list structure'' in order to emphasize that anyconses that areelements of thelist are not involved.)

literaladj. (of anobject) referenced directly in a program rather than being computed by the program; that is, appearing as data in aquoteform, or, if theobject is aself-evaluating object, appearing as unquoted data. ``In the form(cons "one" '("two")), the expressions"one",("two"), and"two" are literal objects.''

loadv.t. (afile) to cause thecode contained in thefile to beexecuted. See thefunctionload.

load timen. the duration of time that the loader isloadingcompiled code.

load time valuen. anobject referred to incode by aload-time-valueform. Thevalue of such aform is some specificobject which can only be computed in the run-timeenvironment. In the case offilecompilation, thevalue is computed once as part of the process ofloading thecompiled file, and not again. See thespecial operatorload-time-value.

loadern. a facility that is part of Lisp and thatloads afile. See thefunctionload.

local declarationn. anexpression which may appear only in specially designated positions of certainforms, and which provides information about the code contained within the containingform; that is, adeclareexpression.

local precedence ordern. (of aclass) alist consisting of theclass followed by itsdirect superclasses in the order mentioned in the definingform for theclass.

local slotn. (of aclass) aslotaccessible in only oneinstance, namely theinstance in which theslot is allocated.

logical blockn. a conceptual grouping of related output used by thepretty printer. See themacropprint-logical-block andSection 22.2.1.1 (Dynamic Control of the Arrangement of Output).

logical hostn. anobject ofimplementation-dependent nature that is used as the representation of a ``host'' in alogical pathname, and that has an associated set of translation rules for convertinglogical pathnames belonging to that host intophysical pathnames. SeeSection 19.3 (Logical Pathnames).

logical host designatorn. adesignator for alogical host; that is, anobject that denotes alogical host and that is one of: astring (denoting thelogical host that it names), or alogical host (denoting itself). (Note that because the representation of alogical host isimplementation-dependent, it is possible that animplementation might represent alogical host as thestring that names it.)

logical pathnamen. anobject oftypelogical-pathname.

long floatn. anobject oftypelong-float.

loop keywordn.Trad. a symbol that is a specially recognized part of the syntax of an extendedloopform. Such symbols are recognized by theirname (usingstring=), not by their identity; as such, they may be in any package. Aloop keyword is not akeyword.

lowercaseadj. (of acharacter) being amongstandard characters corresponding to the small lettersa throughz, or being some otherimplementation-definedcharacter that is defined by theimplementation to belowercase. SeeSection 13.1.4.3 (Characters With Case).