sisc.data
Class Nothing

java.lang.Object
  sisc.util.Util
      sisc.data.Expression
          sisc.data.Value
              sisc.data.Nothing

All Implemented Interfaces:

java.io.Externalizable, java.io.Serializable, Immediate, Singleton, ExpressionVisitee, Version

public class Nothing
extends Value
implements Singleton

A value, unlike "void", which is not equal to anything

See Also:

Serialized Form

Field Summary

static Nothing

NOTHING

Fields inherited from class sisc.data.Expression

annotations, EMPTYSET

Fields inherited from class sisc.util.Util

BACKQUOTE, BEGIN, bundles, caseSensitive, EMPTYLIST, EMPTYVEC, EOF, ERRORK, EVAL, EXPSC, EXPTOP, FALSE, FCONT, FIVE, JEXCEPTION, LAMBDA, LOCATION, maxFloatPrecision, MESSAGE, minFloatPrecision, NAME, OTHER, PARENT, permitInterrupts, QUOTE, QUOTESYM, REPORT, SETBANG, SISC, SISC_SPECIFIC, SISCB, SOURCE_COLUMN, SOURCE_FILE, SOURCE_LINE, SYMENV, THIS, TOPLEVEL, TRUE, UNQUOTE, UNQUOTE_SPLICING, VOID, ZV

Fields inherited from interface sisc.util.Version

VERSION

Constructor Summary

Nothing()

Method Summary

void	display(ValueWriter w)
boolean	eqv(java.lang.Object v) Compares this Value to another for equality according to the rules of Scheme's eqv?.
Value	singletonValue()

Methods inherited from class sisc.data.Value

apply, displayNamedOpaque, equals, eval, express, getValue, synopsis, synopsis, toString, valueEqual, valueHashCode, write, writeReplace

Methods inherited from class sisc.data.Expression

deserialize, deserializeAnnotations, getAnnotation, getAnnotation, getAnnotationKeys, getAnnotations, getName, readExternal, readResolve, serialize, serializeAnnotations, setAnnotation, setAnnotation, setName, visit, visitAnnotations, writeExternal

Methods inherited from class sisc.util.Util

annotated, annotatedAppEval, append, argCheck, argsToSymbols, assq, bininport, bininstream, binoutport, binoutstream, box, character, charinport, charinreader, charoutport, charoutwriter, charsetFromString, chr, cont, currentClassLoader, env, error, error, error, error, error, error, error, expr, getDefaultCharacterSet, immutablePair, immutableVector, inport, javaExceptionToString, javaWrap, justify, length, liMessage, liMessage, liMessage, liMessage, liMessage, liMessage, liMessage, list, list, list, list, list, makeURL, mapcar, memq, nlib, num, outport, pair, pairToExpressions, pairToExpVect, pairToValues, proc, read, registerBundle, reverse, reverseInPlace, simpleErrorToString, sourceAnnotations, str, string, sym, symbol, symval, truePair, truth, truth, typeError, typeError, updateName, url, url, url, valArrayToList, valArrayToList, valArrayToVec, vec, warn, warn, warn

Methods inherited from class java.lang.Object

clone, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

NOTHING

public static Nothing NOTHING

Constructor Detail

Nothing

public Nothing()

Method Detail

eqv

public boolean eqv(java.lang.Object v)

Description copied from class: Value

Compares this Value to another for equality according to the rules of Scheme's eqv?. In SISC, this differs from eq? in that eq? is strict pointer equality.

Overrides:

eqv in class Value

Parameters:

v - the other Value

display

public void display(ValueWriter w)
             throws java.io.IOException

Specified by:

display in class Value

Throws:

java.io.IOException

singletonValue

public Value singletonValue()

Specified by:

singletonValue in interface Singleton