Ask-Elle: a Haskell Tutor - Alex Gerdes

192 Pages·2012·0.77 MB·English

by  Alex Gerdes

A -E : a Haskell Tutor
SK LLE
Proefschrift
terverkrijgingvandegraadvandoctor
aandeOpenUniversiteit
opgezagvanderectormagnificus
prof.mr.A.Oskamp
tenoverstaanvaneendoorhet
Collegevoorpromotiesingesteldecommissie
inhetopenbaarteverdedigen
opvrijdag23november2012teHeerlen
om13:30uurprecies
door
Alex Gerdes
geborenop10juli1978teEmmen
Promotor
Prof. dr. J.Th. Jeuring OpenUniversiteit
UniversiteitUtrecht
Overigeledenbeoordelingscommissie
Prof. dr. dr.h.c. ir. M.J.Plasmeijer RadboudUniversiteit
Prof. dr. S.D.Swierstra UniversiteitUtrecht
Prof. dr. S.J.Thompson UniversityofKent
Prof. dr. M.C.J.D.vanEekelen OpenUniversiteit
RadboudUniversiteit
Prof. dr. ir. S.M.M.Joosten OpenUniversiteit
PrintedbyGildeprintdrukkerijen,Enschede.
CoverbyPeterGerdes.
ISBN978-94-6108-371-5
©AlexGerdes,2012
CONTENTS
1 Introduction 1
1.1 ASK-ELLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2 Relatedworkonprogrammingtutors . . . . . . . . . . . . . . . . . 7
1.3 Structureofthisthesis . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.4 Originofchapters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
I Domainreasoners 13
2 Strategies 15
2.1 Strategiesandfeedback. . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.2 Examplestrategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.3 Alanguageforstrategiesforexercises . . . . . . . . . . . . . . . . . 22
2.4 Strategyfunctions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
2.5 Feedbackbasedonstrategies . . . . . . . . . . . . . . . . . . . . . . 41
2.6 Relatedworkonstrategies . . . . . . . . . . . . . . . . . . . . . . . . 43
3 Astrategyrecogniser 45
3.1 Representinggrammars . . . . . . . . . . . . . . . . . . . . . . . . . 46
3.2 Dealingwithlabels . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
3.3 Smartconstructors . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
iii
Contents
3.4 Runningastrategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
3.5 Tracingastrategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
4 Exercises 57
4.1 Strategyandrules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
4.2 Syntacticandsemanticchecks . . . . . . . . . . . . . . . . . . . . . . 66
4.3 Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
5 Domainreasoners 73
5.1 Feedbackservices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
5.2 Webservices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
5.3 Feedbackscripts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
II HaskellTutor 87
6 AprogrammingtutorforHaskell 89
6.1 Programmingtutoroverview . . . . . . . . . . . . . . . . . . . . . . 91
6.2 Domaindescription . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
6.3 Testingincompleteprograms . . . . . . . . . . . . . . . . . . . . . . 96
6.4 Aninteractivesession . . . . . . . . . . . . . . . . . . . . . . . . . . 97
6.5 Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
7 Specifyingprogrammingexercises 109
7.1 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
7.2 Feedbackscriptsforprogrammingexercises. . . . . . . . . . . . . . 111
7.3 Annotatingmodelsolutions . . . . . . . . . . . . . . . . . . . . . . . 111
8 Constructingprogrammingstrategies 115
8.1 Refinementrules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
8.2 Focusingrefinementrules . . . . . . . . . . . . . . . . . . . . . . . . 120
8.3 Strategiesinfunctionalprogramming . . . . . . . . . . . . . . . . . 123
8.4 Derivingprogrammingstrategies . . . . . . . . . . . . . . . . . . . . 125
9 AcanonicalformforHaskellprograms 129
9.1 Programtransformations. . . . . . . . . . . . . . . . . . . . . . . . . 130
9.2 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
10 Aprogrammingstrategyrecogniser 135
10.1 Paralleltop-downrecogniser . . . . . . . . . . . . . . . . . . . . . . 136
10.2 Searchspacereduction . . . . . . . . . . . . . . . . . . . . . . . . . . 137
iv
Contents
11 AssessingHaskellprograms 143
11.1 Usingourassessmenttool . . . . . . . . . . . . . . . . . . . . . . . . 145
11.2 Relatedworkonassessment . . . . . . . . . . . . . . . . . . . . . . . 148
12 Epilogueandfuturework 151
12.1 Futurework . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
Samenvatting 157
Curriculumvitae 163
Listofacronyms 177
Index 178
v

Acknowledgements
ThelastfiveyearsIparticipatedasa‘promovendus’inaongoingresearchproject
ongeneratingsemanticallyrichfeedback. Ithoroughlyenjoyedthisperiod,and
neverregrettedthedecisionoftakingthisacademicjob. Itinvolvedhardwork,
alotoftravelling,manyinterestingdiscussions,andmuchcoding. Togetherthis
culminatedinthisthesis. DuringmyresearchIreceivedhelpfrommanypeople,
forwhichIamverygrateful.
FirstofallIwouldliketothankmypromotorJohanJeuring,whomIowevery
much. Youhavealwaysbeenverythoroughandprecisewhenreviewingmywork,
andguidedmeintotherightdirectionwhenneeded. Youalwayshadtimeforme,
evenwhenyoumovedtoSwedenforawhile. Youconstantlypushedmetodo
better. Thatwasnotalwayseasy,butIvalueitverymuch. Johan,Iamverylucky
tohavehadyouasmysupervisor;Icouldnothavewishedforabetterone!
Iwouldalsoliketothankthemembersoftheexaminationcommittee(Markovan
Eekelen,StefJoosten,RinusPlasmeijer,DoaitseSwierstra,andSimonThompson)
forreadingandapprovingthemanuscript,andprovidingmewithseveraluseful
comments.
Also,IwouldliketothankBastiaanHeerenforthemanydiscussionswehad
aboutourresearchandtheimplementationofoursoftware. Ilearnedalotfrom
thosediscussions;youareagiftedprogrammer. Furthermore,Iwouldliketothank
LexBijlsmaforbeingtheperfectline-manager,yourresponsetimeislegendary. A
bigthankyougoestoChrisjaMuris,HarriePassier,SylviaStuurman,JosjeLodder,
andtheothercolleaguesattheOpenUniversity. Youmademytimeworkingin
Heerlenveryenjoyable.
IamthankfulforDoaitseSwierstraandtheUtrechtUniversityforhavingmeas
guestduringmyPhD-study. TheSoftwareTechnologygroupisaveryinspiring
environment and an excellent place to do research. I would like to thank José
PedroMagalhães,SeanLeather,AndresLöh,WouterSwierstra,StefanHoldermans,
ArieMiddelkoop,JurriaanHage,AlexeyRodriguezYakushev,andalltheother
colleagues for the really nice time I had in Utrecht. I would also like to thank
myroommate(and‘lotgenoot’)ThomasvanNoort. AnotherthanksgoestoBram
SchuurandBramVaessenforassistingmewiththeexperiments.
IhadthepleasureofmeetingMarySheeranattheCentralEuropeanFunctional
Programmingsummerschool2011inBudapest. Thismeetingeventuallyledtoa
dreamjobatQuviQinGöteborg. MaryIcan’tthankyouenoughforthat! Iwould
alsoliketothankThomasArts,JohnHughes,UlfNorell,andHansSvensson(my
new colleagues at QuviQ) for the warm welcome. You have made the move to
Swedenalotlessdifficult. Tacksåjättemycket!
Finally,IwouldliketothankmyparentsRudieandWilly,mysisterMarloes,my
brotherPeter(whowaskindenoughtodesignthebeautifulcoverofthisthesis),
vii
Acknowledgements
myparentsinlawHillieandHarm,andtherestofmyfamilyandfriendsfortheir
support,understanding,andtime. John,Jos,andGosé,Iamgratefulthatyouare
myfriends. EspeciallyIwouldliketothankmywifeAnitaandmychildrenMats,
Lise,andSofie–youmakeitallworthwhile. Anita,thankyouforwhoyouare;
you’llneverknowtheextentofmygratitude!
AlexGerdes Herrljunga,Autumn2012
viii