Hermes: A Tutorial and Reference Manual - Researcher - IBM
Hermes: A Tutorial and Reference Manual - Researcher - IBM
Hermes: A Tutorial and Reference Manual - Researcher - IBM
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strings,arrays,lists,<strong>and</strong>relations. representinganelementtypestate.Itcancontainthekeywordordered.A 10811.6.TableOperations<br />
canbecompared. typestatetheelementtypestate.Tablescanbeusedtorepresentbags,sets, tabletypedenitioncanalsocontainasetofkeys.Eachkeyiswrittenasa restrictionsguaranteethattableelementscanbecompared,<strong>and</strong>thatkeys initialized,(2)theelementtypestatemustnotbefullyuninitialized.These listofformalvariables.Restrictions:(1)Thevariablesofakeymustbe Atabletypedenitioncontainsanelementtype<strong>and</strong>aformaltypestate<br />
order. ofallkeys.Twoelementsdierinakeyiftheydierinanyvariableofthat key. etcṪwoorderedtablesareequaliftheycontainequalelementsinthesame ments.Therstelementofthetableissaidtohaveposition0,thenext1, Twounorderedtablesareequaliftheirelementscanbeputinone-to-one Thevalueofanorderedtableisanordered(possiblyempty)setofele-<br />
Ifatablehaskeys,anytwoelementsofthetablewillhavedierentvalues<br />
someexamplesoftabletypedenitions. correspondence<strong>and</strong>thecorrespondingelementsareequal.Thefollowingare stringset:tableofstringfinitgkeys(*); string:orderedtableofcharfinitg; intbag:tableofintegerfinitg; person:record(<br />
inconventionallanguages:itisatotallyorderedbag.Typestringset multipleoccurrencesofthesameinteger.Typecharstringislikeastring );id:integer persontable:tableofpersonffullgkeys(name,address)(id); Typeintbagisabag|itcanholdanynumberofintegers,including name:string,<br />
hastheadditionalspecicationthatnotwostringsmaybeequal|thus address:string,<br />
elementscanhavethesamevalueofid.Thistypeactslikeatwo-way mappingbetweenidnumbers<strong>and</strong>name-addresspairs. Newsimple{statement elementscanhavethesamestringsforbothname<strong>and</strong>address,<strong>and</strong>notwo itbehaveslikeaset.Typepersontablehasthepropertythatnotwo ::=newvariable{name
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