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Topic I � Introduction and Motivation

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Topic I � Introduction and Motivation � Topic I � Introduction and motivation References: � Chapter 1of Concepts in programm ing languages by J. C. Mitchell. CUP, 2003. � Chapter 1of Programming languag es: Design and implementation(3 RD EDITION) by T.W. Pr tt !" M. #.$elkowit'. Prentice Hall, )***. � Chapter 1of Programming languag e pragmatics (2ND EDITION) by M. L. ,cott. El-e.ier, 2006. � 5 Goals Critic l thinking bout 1rogr 3mi!2 la!20 ge-. ? What is 1rogr 33i!2 l !20 ge45 Study 1rogr 3mi!2 la!20 ge-. � 6e f 3iliar &ith ba-ic l !20 2e concepts. � 71preciate tr de8off- i! l !20 ge design. Tr ce history, 1preci te evolution !" di.er-ity of ideas. 6e 1re1 red for !e& 1ro2r 33i!2 methods, paradigms. � 6 Why study programming languages? � To i31ro.e the ability to "e.elop effecti.e lgorithms. � To i31ro.e the 0-e of f 3ili r l !20 2es. � To incre -e the .oc b0lary of 0-ef0l pro2r 33i!2 con-truct-. � To llo& better choice of 1rogr 33i!2 l !20 2e. � To 3 %e it e -ier to lear! !e& l !20 ge. � To 3 %e it e -ier to "e-ig! ne& l !20 2e. � To -im0late 0-ef0l feat0re- in l !20 ge- that l c% them. � To 3 %e better 0-e of l !20 2e technology &here.er it 11ear-. � 7 What makes a good language? Clarity, -i31licity, !" 0!ity. Ortho2onality. N turalne-- for the 11lication. ,011ort of bstraction. E -e of pro2r 3 .eri9c tion. Progr 33i!2 e!.iro!3ent-. Portability of 1rogr 3-. � 8 Co-t of 0-e. � Co-t of e:ec0tio!. � Co-t of 1rogr 3 tr !-l tion. � Co-t of 1rogr 3 creatio!, te-ti!2, !" 0-e. � Co-t of 1rogr 3 mai!te! !ce. � 9 What makes a language successful? � E:1re--ive 1o&er. � E -e of 0-e for the !o.ice. � E -e of imple3ent tio!. � O1en -o0rce. � E:cellent co31iler-. � Eco!omic-, 1 tron 2e, !" inertia. � 10 Influences Co31uter c 1abilitie-. 71plic tio!-. Progr 33i!2 method-. I31lementatio! 3etho"-. Theoretic l -t0"ies. ,t !"ar"is tion. � 11 Applications domains Era Application Major languages Other languages )*/0- 60-i!e-- CO6O+ 7--e3bler ,cie!ti9c ;ORTR7N 7+<O+, 67,IC, 7P+ ,y-te3 7--e3bler JO#I7+, ;orth AI +I,P ,NO6O+ To" y 60-i!e-- CO6O+, ,=+, -1re "-heet C, P+>I, ?<+- ,cie!ti9c ;ORTR7N, C, C@@ 67,IC, P -c l M 1le, M the3 tic ,y-te3 6CP+, C, C@@ P -c l, 7" , 67,IC, MODU+7 AI +I,P, Prolo2 P0bli-hi!2 TEA, Po-tcri1t, &ord 1roce--i!2 Proce-- UNIA -hell, TC+, Perl M r.el, E-terel Ne& 1 r "i23- ,3 llt l%, ,M+, ( -%ell, J . Eifell, CB, ,c l Pytho!, R0by � 12 5 Why are there -o 3 !y l !20 ge-5 � E.olution. � ,1ecial 10rpo-e-. � Per-onal 1reference. � 13 ��Motivating application in l !20 ge de-i2!�� 7 -1eci9c 1ur1o-e pro.ide- focus for l !20 2e "esig!er-C it hel1- to -et criteri for 3 %in2 "e-i2! deci-io!-. 7 -1eci9c, 3otivati!2 1plic tio! lso help- to -ol.e one of the har"est 1roblems i! 1ro2r 3min2 la!20 2e de-ig!D deci"in2 &hich feat0res to lea.e out. � 14 Examples: <oo" l !20 2es de-i2!ed &ith -peci9c 10r1ose i! mind. � +I,PD -y3bolic co310tation, 0tomate" re -oni!2 � ;PD f0!ction l pro2r 3min2, algebraic la&- � 6CP+D co31iler &ritin2 � ,i30l D -i30lation � CD -y-te3- 1rogr 33i!2 � MLD theore3 1ro.i!2 � ,3 llt lkD Dy!aboo% � Clu, ,M+ Mo"ulesD 3o"0lar pro2r 3min2 � C++D object orientatio! � J . D I!ternet 11lic tio!- � 15 Program execution model <ood l !20 ge de-ig! 1resent- abstract machine. � ;ORTR7ND ;l t regi-ter 3 chineC 3emory rr !2e" - linear rr y � +I,PD co!- cell-, re "8e. l-1ri!t loop � 7lgol familyD -t c% of activatio! recor"-C he 1 -tor ge � 6CP+, CD 0!derlyin2 3 chine @ bstr ction- � ,i30l D Object references � ;P, MLD f0!ction- re b -ic co!trol -tr0ct0re � ,3 llt lkD object- !" method-, comm0!icati!2 by 3e-- ge- � J . D J . .irt0al 3 chine � 16 ��Cl --i9c tio! of 1ro2r 3mi!2 la!20 2e-�� I31erati.e 1roced0ral C,7"a,Pascal,Algol,FORTRAN,... object orie!te" cala, C#,J . , malltal!, "MU$A,... -criptin2 Perl, Pytho!, P(P, . Decl rati.e f0!ctio! l ( -%ell, ,M+, +i-1, ,che3e, . logic Prolo2 "at Fo& I", #al con-tr int8b -ed -1re "-heet- template-b -e" A,+T � 17 Theoretical foundations Examples: � ;or3 l-l !20 2e theory. � 7uto3 t theory. � 7lgorithmic-. � λ8calc0l0-. � ,e3 ntic-. � ;or3 l .erific tio!. � Ty1e theory. � Co31le:ity theory. � +ogic. � 18 Standardisation Proprietary -t !" r"-. Co!-e!-0- -t !"ar"-. � 7N,I. � IEEE. � 6,I. � I,O. � 19 Language standardisation Co!-iderD int i; i = (1 && 2) + 3 ; ? I- it .ali" C code? If -o, &hatG- the .alue of i5 ? (o& "o &e !-&er -0ch H0estio!-45 % Re " the reference 3 !0al. % Try it !" -ee4 % Re " the 7N,I C ,t !"ar". � 20 Language8standards issues Timeliness. Whe! "o &e -t !"ar"ise l !20 ge5 Conformance& What does it 3e ! for 1ro2r 3 to dhere to -t !"ar" !" for co31iler to compile -t !" r"5 Ambiguity and freedom to optimise — Machine dependence — Undefined behaviour O'solescence& Whe! "oes -t !" r" ge !" ho& "oe- it 2et 3odi9ed5 Deprecated features � 21 Language standards PL/1 ? What does the followin2 9 + 8/3 3e !5 − 11.666... 5 − O.erFo& 5 − 1.666... 5 � 22 DEC(p,q) 3e !- p "igit- &ith q fter the deci3 l point. Ty1e rule- for DECIM7+ i! P+>)D DEC(p1,q1) + DEC(p2,q2) => DEC(MIN(1+MAX(p1-q1,p2-q2)+MAX(q1,q2),15),MAX(q1,q2)) DEC(p1,q1) / DEC(p2,q2) => DEC(15,15-((p1-q1)+q2)) � 23 ;or 9 + 8/3 &e h .eD DEC(1,0) + DEC(1,0)/DEC(1,0) => DEC(1,0) + DEC(15,15-((1-0)+0)) => DEC(1,0) + DEC(15,14) => DEC(MIN(1+MAX(1- ,15-14)+MAX(0,14),15),MAX(0,1!)) => DEC(15,14) ,o the calc0lation i- - follo&- 9 + 8/3 = 9 + 2.66666666666666 = 11.66666666666666 - "#ER%&"' = 1.66666666666666 - "#ER%&"' (is*+,-( � 24 istory 1()1–)5: E:1eri3ent l 0-e of e:1res-ion compiler-. 1()+*+0: FORTRAN, CO6O+, $" P, Algol 60. 1(+1–+5: 7P+ !ot tion, 7l2ol 60 (re.i-ed), ,NO6OL, CPL. 1(++*-0: 7PL, ,NO6O+ ?, ;ORTR7N //, 67,IC, "M#$A, 7lgol /I, 7lgol8W, 6CPL. 1(-1–-5: Pascal, P+>) (,t !" rd), C, ,che3e, Prolog. 1(-+*.0: malltal!, 7" , ;ORTR7N J7, ML. � 25 1(.1–.5: ,3 llt lk8I0, Prolog, 7" I3. 1(.+*(0: C@@, M$, ( -%ell. 1((1–(5: 7" *5, TCL, Perl. 1((+*/,,0: J .a. /,,,*,5: CB, Pytho!, R0by, cala. � 26 Language groups M0lti-1ur1o-e la!20 2e- � ,c la, CB, J . , C@@, C � ( -%ell, ,M+, Scheme, LI,P � Perl, Python, R0by ,1ecial810rpo-e l !20 2es � UNIA -hell � ,=+ � +7TEA � 27 Things to think a!out What 3 %es 2oo" l !20 ge5 The role of 1. 3oti. ti!2 11lication-, 2. 1rogr 3 e:ecution, 3. theoretic l fo0!"ation- i! l !20 ge "esign. + !20 ge -t !" rdi- tion. � 28.
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