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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constructs:thenewinput-port,connect<strong>and</strong>createstatements,<strong>and</strong>the InterfaceMismatchexception.Congratulations!Younowknowsixofthe 1.5Declarations<strong>and</strong>Denitions ten<strong>Hermes</strong>systemprogrammingstatements! 181.4.PuttingProcessesTogether<br />
morphic <strong>and</strong>howmuchshouldbeinferredbythecompilerShouldtypesbepoly-<br />
muchshouldtheprogrammerhavetowriteoutasexplicitdeclarations, averyimportantlooseendmentionedearlier|declarations<strong>and</strong>denitions. checking.Shouldtypecheckingbedoneatcompile-timeorrun-timeHow Let'stakeabreakfromlearningnewkindsof<strong>Hermes</strong>statements,<strong>and</strong>tieup <strong>Hermes</strong>takesthefollowingpositions: Thereismuchdebate<strong>and</strong>dierenceofopinionabouttheroleoftype Allprogramswillproducesemanticallywell-denedlocalizedeects| Programmingerrorswillbedetectedatcompiletimewhereverpossible.<br />
Programmersmustdeclarethetypesofallvariablesexceptexpression Infact,aprocesscanaccessonlythedatabelongingtoit. eitheranormalresultoranexception.Thismeansprogrammingbugs<br />
Therearenopolymorphictypes.They'renotneededasmuchwhen can'tcrashthesystem,orwriter<strong>and</strong>omgarbageintoanotherprocess.<br />
itlyintroducingpolymorphism.(<strong>Hermes</strong>hasapolymorphtype,which samegoal|namely,reusablesourcecodepackages|withoutexplic-<br />
insteadwritesatemplate<strong>and</strong>thencreatesspecicsortprogramsby substitutingspecictypesintothetemplate.Thisaccomplishesthe writingapolymorphicsortprogramwhichcansortanytype,one youhavetheabilitytocreateprogramobjectsonthey.Insteadof temporaries.Thecompilerinfersthetypesofexpressiontemporaries.<br />
statementsweshowedyouearlier. 1.5.1Declarations Wewillnowshowyouthecompletetextoftheprogramswhoseexecutable HelloWorld:using(St<strong>and</strong>ard)process(Init:St<strong>and</strong>ardIn) allowsavariabletoholdavalueofanytype,therebydeferringtype<br />
declare checkinguntilrun-time.)<br />
begin Parms:St<strong>and</strong>ardInterface;--callmessagereceivedfromparent receiveParmsfromInit;
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