Listoflectures
IntroductionandFunctionalProgramming
ImperativeProgrammingandDataStructures
3
Environment
4
Evaluation
5
ObjectOrientedProgramming
6
Macrosand
7
VirtualMachinesandBytecode
8
GarbageCollectionandNativeCode
9
ParallelandDistributedComputing
10
DeclarativeandLogicProgrammingandStatic
ProgramAnalysis
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Summary
1
2
TDDA69DataandProgramStructure
Summary
CyrilleBerger
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Lecturegoal
Lecturecontent
Provideasummaryofwhat
hasbeenstudiedinthelecture
Demonstratehowthe
conceptsconnecttogether
Theconscequencesofthedesign
choiceinprogramminglanguages
Choosinganappropriate
ProgrammingLanguageParadigm
Thedifferenttypesofinterpreter
Thedynamic/staticbalance
inImperativeProgramming
Languages
Final
Whatisincluded?
Examples
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Doweneednewprogramminglanguages?
NewConcepts(intheearly
days,objectorientation)
Newproblemsandnew
infrastructure(multi-threading,
distributedcomputing...)
Developabetter
MotivationforcreatingGo
RobPike,Gocreator:‟Acoupleofyearsago,several
ofusatGooglebecamealittlefrustratedwiththe
softwaredevelopmentprocess,andparticularlyusing
C++towritelargeserversoftware.Wefoundthatthe
binariestendedtobemuchtoobig.Theytook
toolongtocompile.Andthelanguageitself,which
isprettymuchthemainsystemsoftwarelanguagein
theworldrightnow,isaveryoldlanguage.Alotof
theideasandchangesinhardwarethathave
comeaboutinthelastcoupleofdecadeshaven’thad
achancetoinfluenceC++.”
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MotivationforcreatingRust
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UsageofC++vsGovsRust
GraydonHoare,Rustcreator:‟Alotofobviousgood
ideas,knownandlovedinotherlanguages,haven't
madeitintowidely-usedsystemslanguages,orare
deployedinlanguagesthathaveverypoor(unsafe,
concurrency-hostile)memorymodels.Therewerealotof
goodcompetitorsinthelate70sandearly80sinthat
space,andIwantedtorevivesomeoftheirideasand
givethemanothergo,onthetheorythatcircumstances
havechanged:theinternetishighlyconcurrentandhighly
security-conscious,sothedesign-tradeoffsthatalways
favorCandC++(forexample)havebeenshifting.”
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Isiteasiertochangeandfixexistinglanguages?
Backward-compatiblechanges
Backward-incompatiblechanges
PHPCriticism
PHPwasnotdesigned,butdeveloped
organically
Inconsistentnamingoffunctionsandorderoftheir
Somechangesaretoo
IntroducingUnicodeinPythonand
GarbagecollectorinC+
Somefunctionnameswerechosentoimprovethedistributionofhashvalues
Ratherthanabortingwithanerror,PHPwilltrytoguess
thedeveloperintent
Problemswithweaktyping
Thosechangesintroducelong
developmenttimeandlong
acceptancetime
PHPcompilationoptions,serverconfigurations,applications
configurationsandglobalstatescanaffectfunction
behaviour
Incoherentmixbetweenfunctionalandobjectorientedprogramming
...
Youneedavisionandadesignwhendeveloping
aprogramminglanguage!
Python3.0wasintroducedin
PHP6wasstartedin2006andnever
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DesignConsiderationforaProgrammingLanguage
Aprogramminglanguagemustbe:
predictable
Sourcecodeisreadmoreoftenthanwritten,ahumanmustbeableto
understandwhatheread
consistent
Knowingpartofalanguageshouldhelplearnotherparts
concise,simpleandgeneral
reliable
Programminglanguageareheretosolveproblem,nottointroducenewone
debuggable
Developerswillinevabilitywritebugs,theyneedallthehelptheycangetto
findthem
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DesignchoicesforaProgrammingLanguage
ProgrammingParadigm
DynamicvsStatic
Low-levelvsHigh-level
Directinterpretation,Virtual
Machine,JIT,Native
Compilation...
implementable
Thisreducethenumberofbugsinthelanguageimplementation
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Whatisthepurposeofthenewlanguage?
Firstquestionis,anew
language,whatfor?
Choosinganappropriate
ProgrammingLanguageParadigm
Queryingknowledge?
Distributednumericalcomputation?
WrittingdriversforanOperatingSystem?
Writtingwebapplications?
AnsweringtheUltimateQuestionofLife,the
Universe,andEverything
...
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Declarative
ProgrammingParadigms
Expresseslogicofcomputation
withoutcontrolflow:
Imperative
declarative
functional
Whatshouldbecomputedandnothowit
shouldbecomputed.
Examples:XML/HTML,antlr4/yacc,
make/ants...
Logic
Object-Oriented
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Functional
LogicProgramming
Computationaretreated
asmathematicalfunction
BasedonFormallogic:expressing
factsandrules
Examples:Prolog
withoutchanginganyinternalstate
Examples:Lisp,Scheme,
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Imperative
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Object-Oriented
Expresshowcomputationare
executed
Basedontheconceptofobjects,
whicharedatastructures
containingfieldsandmethods
Describescomputationintermofstatements
thatchangetheinternalstate
Programsaredesignedbymakingobjects
interactwitheachothers
Examples:C/C++,Pascal,
Java,Python,JavaScript...
Examples:C++,Java,C#,
Python,Ruby,JavaScript...
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Conscequencesofthechoice
Howtochooseaprogrammingparadigm?
Conscequencefortheusers
Thechoicedependsonthegoal
Querying
Expressivity,simplicity,readability
Conscequenceonthe
implementation
⇒Declarativeorlogic(reasoning)
Distributednumerical
⇒Functional
WrittingdriversforanOperating
Differenttypesofinterpreters
⇒Imperative
Writtingweb
⇒Object-Oriented
Thechoicecanbeconsidered
controversial!
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Howisaprograminterpreted?
Sourcecode
Thedifferenttypesofinterpreter
Parser
Parser
AbstractSyntaxTree
Treevisitor
Generator
Sourcecode
Bytecode
VirtualMachine
Assembler
Assembly
...
OperatingSystem
CPU
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InterpretingDeclarativeandLogic
InterpretingFunctional
Usingaqueryexecutor(forSQL)
Usingareasoningengine(for
Prolog)
Functionsareevaluatedinorder
ApplicativevsNormal
Innormalorder,thetreeneedsto
beexpanded,virtualmachines
aremoredifficult
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InterpretingImperative/Object-oriented
Directlyfromtheabstract
syntaxtree
Usingvirtualmachines
RunningontheCPU
Themoreversatile,the
morecommon,themost
studied
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Conscequencesofthechoiceofprogrammingparadigm
Generality,expressivity
andsimplicity
Howtointerpret
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Dynamicvsstatic
Thedynamic/staticbalanceinImperativeProgrammingLanguages
Dynamic/statictyping,
classdefinition
Strong/Weaktyping
Abalancebetweeneaseof
use,performanceand
validation
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ClassDefinition
Type-Checking
Static-typechecking
Staticclass
Dynamic-typechecking
Dynamicclass
Typesarecheckedatcompilationfromstatic
analysis
Usuallyvariableshaveasingletype
Polymorphismallowsfordynamicity
Supportfromdowncasting
Classmembersandfunctionsaredefinedat
compilation
Eachobjectisassociatedtoaclassprototype
Example:C++,Java
Classmembersandfunctionscanbechanged
duringruntime
Example:JavaScript,Python
Typesarecheckedatruntime
Thetypeofavariablecanchange
Unchecked
Example:machinecode
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Dynamicvsstatic
Strong/Weaktyping
Advantagesof
Typecastingistheprocessofconvertingfrom
onetypeofvaluetoanother
Performance
Checking
Forinstnace,fromanintegertoastring
Canbeimplicitorexplicit
Astrongtypingrequiremoreexplicitconversion
Forinstance,inRust,itisusedtocheckthreading
issues
ThestrongestisAda,itonlyallows
C++,Java,Pythonallowreasonableimplicitconversion
Advantagesofdynamic:
10+5.0->15.0
10+'5'->Error
Easierfortheuser
Aweaktypingrequirefewexplicitconversion
Example:php
10+5.0->15.0
10+'5'->'105'
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Conscequenceontheinterpreter
With
Checkingmustbeimplementedinthe
compiler
Finalexam
With
Checkingmustbeimplementedduring
interpretation
Itishardertocompileoptimizedcodefor
runningonthehardware
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Programmingparadigms
Functionalprogramming(lec
1,3,4,sicp1)
Imperativeprogramming(lec
2,3,4)
Objectorientedprogramming
(sicp3,lec5)
Logicprogramming(sicp4.4,lec
10)
Whatisincluded?
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Modularity,state
Metalinguisticabstraction
assignmentandlocalstate(sicp
3.1,lab1)
environmentmodelof
evaluation(sicp3.2,lab1,2,lec
3)
streams(sicp3.5)
eventdrivensimulation(sicp3.3.4)
constraintprogramming(sicp
3.3.5,lab1)
metacircularevaluator(sicp
lazyevaluation,parameterpassing
withcall-by-value,call-by-nameand
call-by-need(sicp4.2,lec4)
macrosandspecialforms(lab4,lec6)
non-deterministincprogrammingand
continuations(sicp4.3)
declarativeandproceduralprogramming
(sicp4.4,lec10),patternmatchingand
unification(lec10)
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Virtualmachinesandcompilation
explicitcontrolevaluator(sicp5.4)
recursionanditeration(sicp5.1.4,
lec1)
compilerforJavaScript(lab
2,3,5,6)
garbagecollection(sicp5.3,lec8)
Examples
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Environmentmodel
Concepts
Assumetheexpressionbelowisevaluatedintheorder
itisgiven.Whatwilltheresultbe?Drawadiagram
thatcaptureswhatisgoingonaccordingtothe
environmentmodelofevaluation.Marktheimportant
structuresandexplainwhy,andinwhatorder,they
arecreatedand(canbe)eleminated.Usethediagram
toshowtheresultoftheevaluation.
functionf(x)
{
returng(x+3)(4,5);
}
functiong(y,z)
{
returnfunction(y,z){returnz+(y*x);}
}
f(3)
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Explainthefollowingconcepts
substitutionmodelofevaluation
tailrecursion
call-be-need
unification
constraint
abstractsyntax
continuations
normalorder
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Compilersandinterpreters
ProgrammingLanguageDesign
Explaintheadvantagesand
disadvantagesthatcharacterize
compilersversusinterpreters.
Whenisitmoreappropriateto
useacompiler?aninterpreter?
Youaretaskedtowritea
programminglanguagefor
executingdistributedprograms.
Whatparadigmdoyouchoose
andwhy?
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Logicprogramming
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Conclusion
Implementthepredicatemultiple
inPrologorQLog.Itshould
decidewhetheralistcontains
thesameelementtwoormore
(multiple(abdbc));;istrue
times.
(multiple(abcd));;isfalse
Theneedfornewandchangeto
existingprogramminglanguages
Theneedforadesignandavision
Theinfluenceonchoosinga
paradigmanddynamicity/
staticforinterpretation
Final
Youcanusetheappend
predicatewithoutdefiningit.
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