CLHS: Glossary-Section S

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S

safe adj. 1. (of code) processed in a lexical environment where the the highest safety level (`3`) was in effect. See optimize. 2. (of a call) a safe call.

safe call n. a call in which the call, the function being called, and the point of functional evaluation are all safe[1] code. For more detailed information, see Section 3.5.1.1 (Safe and Unsafe Calls).

same adj. 1. (of objects under a specified predicate) indistinguishable by that predicate. ``The symbol `car`, the string `"car"`, and the string `"CAR"` are the `same` under string-equal''. 2. (of objects if no predicate is implied by context) indistinguishable by eql. Note that eq might be capable of distinguishing some numbers and characters which eql cannot distinguish, but the nature of such, if any, is implementation-dependent. Since eq is used only rarely in this specification, eql is the default predicate when none is mentioned explicitly. ``The conses returned by two successive calls to cons are never the same.'' 3. (of types) having the same set of elements; that is, each type is a subtype of the others. ``The types specified by `(integer 0 1)`, `(unsigned-byte 1)`, and `bit` are the same.''

satisfy the test v. (of an object being considered by a sequence function) 1. (for a one argument test) to be in a state such that the function which is the predicate argument to the sequence function returns true when given a single argument that is the result of calling the sequence function's key argument on the object being considered. See Section 17.2.2 (Satisfying a One-Argument Test). 2. (for a two argument test) to be in a state such that the two-place predicate which is the sequence function's test argument returns true when given a first argument that is the object being considered, and when given a second argument that is the result of calling the sequence function's key argument on an element of the sequence function's sequence argument which is being tested for equality; or to be in a state such that the test-not function returns false given the same arguments. See Section 17.2.1 (Satisfying a Two-Argument Test).

scope n. the structural or textual region of code in which references to an object, a binding, an exit point, a tag, or an environment (usually by name) can occur.

script n. ISO one of possibly several sets that form an exhaustive partition of the type character. See Section 13.1.2.1 (Character Scripts).

secondary value n. (of values resulting from the evaluation of a form) the second value, if any, or else nil if there are fewer than two values. ``The secondary value returned by truncate is a remainder.''

section n. a partitioning of output by a conditional newline on a pretty printing stream. See Section 22.2.1.1 (Dynamic Control of the Arrangement of Output).

self-evaluating object n. an object that is neither a symbol nor a cons. If a self-evaluating object is evaluated, it yields itself as its only value. ``Strings are self-evaluating objects.''

semi-standard adj. (of a language feature) not required to be implemented by any conforming implementation, but nevertheless recommended as the canonical approach in situations where an implementation does plan to support such a feature. The presence of semi-standard aspects in the language is intended to lessen portability problems and reduce the risk of gratuitous divergence among implementations that might stand in the way of future standardization.

semicolon n. the standard character that is called ``semicolon'' (`;`). See Figure 2-5.

sequence n. 1. an ordered collection of elements 2. a vector or a list.

sequence function n. one of the functions in Figure 17-1, or an implementation-defined function that operates on one or more sequences. and that is defined by the implementation to be a sequence function.

sequential adj. Trad. (of binding or assignment) done in the style of setq, let*, or do*; that is, interleaving the evaluation of the forms that produce values with the assignments or bindings of the variables (or places). See parallel.

sequentially adv. in a sequential way.

serious condition n. a condition of type serious-condition, which represents a situation that is generally sufficiently severe that entry into the debugger should be expected if the condition is signaled but not handled.

session n. the conceptual aggregation of events in a Lisp image from the time it is started to the time it is terminated.

set v.t. Trad. (any variable or a symbol that is the name of a dynamic variable) to assign the variable.

setf expander n. a function used by setf to compute the setf expansion of a place.

setf expansion n. a set of five expressions[1] that, taken together, describe how to store into a place and which subforms of the macro call associated with the place are evaluated. See Section 5.1.1.2 (Setf Expansions).

setf function n. a function whose name is `(setf` symbol`)`.

setf function name n. (of a symbol S) the list `(setf` S`)`.

shadow v.t. 1. to override the meaning of. ``That binding of `X` shadows an outer one.'' 2. to hide the presence of. ``That macrolet of `F` shadows the outer flet of `F`.'' 3. to replace. ``That package shadows the symbol `cl:car` with its own symbol `car`.''

shadowing symbol n. (in a package) an element of the package's shadowing symbols list.

shadowing symbols list n. (of a package) a list, associated with the package, of symbols that are to be exempted from `symbol conflict errors' detected when packages are used. See the function package-shadowing-symbols.

shared slot n. (of a class) a slot accessible in more than one instance of a class; specifically, such a slot is accessible in all direct instances of the class and in those indirect instances whose class does not shadow[1] the slot.

sharpsign n. the standard character that is variously called ``number sign,'' ``sharp,'' or ``sharp sign'' (`#`). See Figure 2-5.

short float n. an object of type short-float.

sign n. one of the standard characters ```+`'' or ```-`''.

signal v. to announce, using a standard protocol, that a particular situation, represented by a condition, has been detected. See Section 9.1 (Condition System Concepts).

signature n. (of a method) a description of the parameters and parameter specializers for the method which determines the method's applicability for a given set of required arguments, and which also describes the argument conventions for its other, non-required arguments.

similar adj. (of two objects) defined to be equivalent under the similarity relationship.

similarity n. a two-place conceptual equivalence predicate, which is independent of the Lisp image so that two objects in different Lisp images can be understood to be equivalent under this predicate. See Section 3.2.4 (Literal Objects in Compiled Files).

simple adj. 1. (of an array) being of type simple-array. 2. (of a character) having no implementation-defined attributes, or else having implementation-defined attributes each of which has the null value for that attribute.

simple array n. an array of type simple-array.

simple bit array n. a bit array that is a simple array; that is, an object of type `(simple-array bit)`.

simple bit vector n. a bit vector of type simple-bit-vector.

simple condition n. a condition of type simple-condition.

simple general vector n. a simple vector.

simple string n. a string of type simple-string.

simple vector n. a vector of type simple-vector, sometimes called a ``simple general vector.'' Not all vectors that are simple are simple vectors---only those that have element type t.

single escape n., adj. 1. n. the syntax type of a character that indicates that the next character is to be treated as an alphabetic[2] character with its case preserved. For details, see Section 2.1.4.6 (Single Escape Character). 2. adj. (of a character) having the single escape syntax type. 3. n. a single escape[2] character. (In the standard readtable, slash is the only single escape.)

single float n. an object of type single-float.

single-quote n. the standard character that is variously called ``apostrophe,'' ``acute accent,'' ``quote,'' or ``single quote'' (`'`). See Figure 2-5.

singleton adj. (of a sequence) having only one element. ```(list 'hello)` returns a singleton list.''

situation n. the evaluation of a form in a specific environment.

slash n. the standard character that is variously called ``solidus'' or ``slash'' (`/`). See Figure 2-5.

slot n. a component of an object that can store a value.

slot specifier n. a representation of a slot that includes the name of the slot and zero or more slot options. A slot option pertains only to a single slot.

source code n. code representing objects suitable for evaluation (e.g., objects created by read, by macro expansion, or by compiler macro expansion).

source file n. a file which contains a textual representation of source code, that can be edited, loaded, or compiled.

space n. the standard character <Space>, notated for the Lisp reader as `#\Space`.

special form n. a list, other than a macro form, which is a form with special syntax or special evaluation rules or both, possibly manipulating the evaluation environment or control flow or both. The first element of a special form is a special operator.

special operator n. one of a fixed set of symbols, enumerated in Figure 3-2, that may appear in the car of a form in order to identify the form as a special form.

special variable n. Trad. a dynamic variable.

specialize v.t. (a generic function) to define a method for the generic function, or in other words, to refine the behavior of the generic function by giving it a specific meaning for a particular set of classes or arguments.

specialized adj. 1. (of a generic function) having methods which specialize the generic function. 2. (of an array) having an actual array element type that is a proper subtype of the type t; see Section 15.1.1 (Array Elements). ```(make-array 5 :element-type 'bit)` makes an array of length five that is specialized for bits.''

specialized lambda list n. an extended lambda list used in forms that establish method definitions, such as defmethod. See Section 3.4.3 (Specialized Lambda Lists).

spreadable argument list designator n. a designator for a list of objects; that is, an object that denotes a list and that is a non-null list L1 of length n, whose last element is a list L2 of length m (denoting a list L3 of length m+n-1 whose elements are L1i for i < n-1 followed by L2j for j < m). ``The list (1 2 (3 4 5)) is a spreadable argument list designator for the list (1 2 3 4 5).''

stack allocate v.t. Trad. to allocate in a non-permanent way, such as on a stack. Stack-allocation is an optimization technique used in some implementations for allocating certain kinds of objects that have dynamic extent. Such objects are allocated on the stack rather than in the heap so that their storage can be freed as part of unwinding the stack rather than taking up space in the heap until the next garbage collection. What types (if any) can have dynamic extent can vary from implementation to implementation. No implementation is ever required to perform stack-allocation.

stack-allocated adj. Trad. having been stack allocated.

standard character n. a character of type standard-char, which is one of a fixed set of 96 such characters required to be present in all conforming implementations. See Section 2.1.3 (Standard Characters).

standard class n. a class that is a generalized instance of class standard-class.

standard generic function a function of type standard-generic-function.

standard input n. the input stream which is the value of the dynamic variable *standard-input*.

standard method combination n. the method combination named standard.

standard object n. an object that is a generalized instance of class standard-object.

standard output n. the output stream which is the value of the dynamic variable *standard-output*.

standard pprint dispatch table n. A pprint dispatch table that is different from the initial pprint dispatch table, that implements pretty printing as described in this specification, and that, unlike other pprint dispatch tables, must never be modified by any program. (Although the definite reference ``the standard pprint dispatch table'' is generally used within this document, it is actually implementation-dependent whether a single object fills the role of the standard pprint dispatch table, or whether there might be multiple such objects, any one of which could be used on any given occasion where ``the standard pprint dispatch table'' is called for. As such, this phrase should be seen as an indefinite reference in all cases except for anaphoric references.)

standard readtable n. A readtable that is different from the initial readtable, that implements the expression syntax defined in this specification, and that, unlike other readtables, must never be modified by any program. (Although the definite reference ``the standard readtable'' is generally used within this document, it is actually implementation-dependent whether a single object fills the role of the standard readtable, or whether there might be multiple such objects, any one of which could be used on any given occasion where ``the standard readtable'' is called for. As such, this phrase should be seen as an indefinite reference in all cases except for anaphoric references.)

standard syntax n. the syntax represented by the standard readtable and used as a reference syntax throughout this document. See Section 2.1 (Character Syntax).

standardized adj. (of a name, object, or definition) having been defined by Common Lisp. ``All standardized variables that are required to hold bidirectional streams have ```-io*`'' in their name.''

startup environment n. the global environment of the running Lisp image from which the compiler was invoked.

step v.t., n. 1. v.t. (an iteration variable) to assign the variable a new value at the end of an iteration, in preparation for a new iteration. 2. n. the code that identifies how the next value in an iteration is to be computed. 3. v.t. (code) to specially execute the code, pausing at intervals to allow user confirmation or intervention, usually for debugging.

stream n. an object that can be used with an input or output function to identify an appropriate source or sink of characters or bytes for that operation.

stream associated with a file n. a file stream, or a synonym stream the target of which is a stream associated with a file. Such a stream cannot be created with make-two-way-stream, make-echo-stream, make-broadcast-stream, make-concatenated-stream, make-string-input-stream, or make-string-output-stream.

stream designator n. a designator for a stream; that is, an object that denotes a stream and that is one of: t (denoting the value of *terminal-io*), nil (denoting the value of *standard-input* for input stream designators or denoting the value of *standard-output* for output stream designators), or a stream (denoting itself).

stream element type n. (of a stream) the type of data for which the stream is specialized.

stream variable n. a variable whose value must be a stream.

stream variable designator n. a designator for a stream variable; that is, a symbol that denotes a stream variable and that is one of: t (denoting *terminal-io*), nil (denoting *standard-input* for input stream variable designators or denoting *standard-output* for output stream variable designators), or some other symbol (denoting itself).

string n. a specialized vector that is of type string, and whose elements are of type character or a subtype of type character.

string designator n. a designator for a string; that is, an object that denotes a string and that is one of: a character (denoting a singleton string that has the character as its only element), a symbol (denoting the string that is its name), or a string (denoting itself). The intent is that this term be consistent with the behavior of string; implementations that extend string must extend the meaning of this term in a compatible way.

string equal adj. the same under string-equal.

string stream n. a stream of type string-stream.

structure n. an object of type structure-object.

structure class n. a class that is a generalized instance of class structure-class.

structure name n. a name defined with defstruct. Usually, such a type is also a structure class, but there may be implementation-dependent situations in which this is not so, if the `:type` option to defstruct is used.

style warning n. a condition of type style-warning.

subclass n. a class that inherits from another class, called a superclass. (No class is a subclass of itself.)

subexpression n. (of an expression) an expression that is contained within the expression. (In fact, the state of being a subexpression is not an attribute of the subexpression, but really an attribute of the containing expression since the same object can at once be a subexpression in one context, and not in another.)

subform n. (of a form) an expression that is a subexpression of the form, and which by virtue of its position in that form is also a form. ```(f x)` and `x`, but not `exit`, are subforms of `(return-from exit (f x))`.''

subrepertoire n. a subset of a repertoire.

subtype n. a type whose membership is the same as or a proper subset of the membership of another type, called a supertype. (Every type is a subtype of itself.)

superclass n. a class from which another class (called a subclass) inherits. (No class is a superclass of itself.) See subclass.

supertype n. a type whose membership is the same as or a proper superset of the membership of another type, called a subtype. (Every type is a supertype of itself.) See subtype.

supplied-p parameter n. a parameter which recieves its generalized boolean value implicitly due to the presence or absence of an argument corresponding to another parameter (such as an optional parameter or a rest parameter). See Section 3.4.1 (Ordinary Lambda Lists).

symbol n. an object of type symbol.

symbol macro n. a symbol that stands for another form. See the macro symbol-macrolet.

synonym stream n. 1. a stream of type synonym-stream, which is consequently a stream that is an alias for another stream, which is the value of a dynamic variable whose name is the synonym stream symbol of the synonym stream. See the function make-synonym-stream. 2. (to a stream) a synonym stream which has the stream as the value of its synonym stream symbol. 3. (to a symbol) a synonym stream which has the symbol as its synonym stream symbol.

synonym stream symbol n. (of a synonym stream) the symbol which names the dynamic variable which has as its value another stream for which the synonym stream is an alias.

syntax type n. (of a character) one of several classifications, enumerated in Figure 2-6, that are used for dispatch during parsing by the Lisp reader. See Section 2.1.4 (Character Syntax Types).

system class n. a class that may be of type built-in-class in a conforming implementation and hence cannot be inherited by classes defined by conforming programs.

system code n. code supplied by the implementation to implement this specification (e.g., the definition of mapcar) or generated automatically in support of this specification (e.g., during method combination); that is, code that is not programmer code.

The following X3J13 cleanup issues, not part of the specification, apply to this section:

- STRING-COERCION:MAKE-CONSISTENT
- PATHNAME-STREAM:FILES-OR-SYNONYM
- CLOSED-STREAM-OPERATIONS:ALLOW-INQUIRY
- WITH-STANDARD-IO-SYNTAX-READTABLE:X3J13-MAR-91
- DEFINE-COMPILER-MACRO:X3J13-NOV89
- LISP-SYMBOL-REDEFINITION-AGAIN:MORE-FIXES
- SETF-METHOD-VS-SETF-METHOD:RENAME-OLD-TERMS

Copyright 1996-2001, Xanalys Inc. All rights reserved.