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 author       = "Martin Abadi and Luca Cardelli and Pierre-Louis Curien and Jean-Jacques Lévy",
 year         = "1990",
 title        = "Explicit Substitutions",
 booktitle    = "Proceedings of the 17th ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages",
 series       = "POPL '90",
 publisher    = "ACM",
 address      = "New York, NY, USA",
 pages        = "31--46",
 doi          = "10.1145/96709.96712",
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 author       = "Adam Bakewell and Colin Runciman",
 year         = "2000",
 title        = "The Space Usage Problem: An Evaluation Kit for Graph Reduction Semantics",
 booktitle    = "Selected Papers from the 2nd Scottish Functional Programming Workshop (SFP00)",
 publisher    = "Intellect Books",
 address      = "Exeter, UK",
 pages        = "115--128",
 doi          = "10.1.1.23.3087",
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@book(Bird,
 author       = "Richard S. Bird and Philip. Wadler",
 year         = "1998",
 title        = "Introduction to functional programming using {H}askell",
 publisher    = "Prentice-Hall",
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@article(chakravarty2004risks,
 author       = "Manuel M.T. Chakravarty and Gabriele Keller",
 year         = "2004",
 title        = "The risks and benefits of teaching purely functional programming in first year.",
 journal      = "Journal of Functional Programming",
 volume       = "14",
 number       = "1",
 pages        = "113--123",
 doi          = "10.1017/S0956796803004805",
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@incollection(chitil:hat,
 author       = "Olaf Chitil and Colin Runciman and Malcolm Wallace",
 year         = "2003",
 title        = "Transforming Haskell for Tracing",
 editor       = "Ricardo Pe\~na and Thomas Arts",
 booktitle    = "Implementation of Functional Languages",
 series       = "Lecture Notes in Computer Science",
 volume       = "2670",
 publisher    = "Springer Berlin Heidelberg",
 pages        = "165--181",
 doi          = "10.1007/3-540-44854-3\_11",
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 author       = "Koen Claessen and John Hughes",
 year         = "2000",
 title        = "QuickCheck: A Lightweight Tool for Random Testing of Haskell Programs",
 booktitle    = "Proceedings of the Fifth ACM SIGPLAN International Conference on Functional Programming",
 series       = "ICFP '00",
 publisher    = "ACM",
 address      = "New York, NY, USA",
 pages        = "268--279",
 doi          = "10.1145/351240.351266",
)
@book(gerdes2012ask,
 author       = "Alex Gerdes",
 year         = "2012",
 title        = "Ask-Elle: a Haskell Tutor",
 publisher    = "PhD thesis, Open Universiteit Nederland",
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@article(Heeren2014110,
 author       = "Bastiaan Heeren and Johan Jeuring",
 year         = "2014",
 title        = "Feedback services for stepwise exercises",
 journal      = "Science of Computer Programming",
 volume       = "88",
 number       = "0",
 pages        = "110 -- 129",
 doi          = "10.1016/j.scico.2014.02.021",
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@article(rewritestrategiesforexercises,
 author       = "Bastiaan Heeren and Johan Jeuring and Alex Gerdes",
 year         = "2010",
 title        = "Specifying Rewrite Strategies for Interactive Exercises",
 journal      = "Mathematics in Computer Science",
 volume       = "3",
 number       = "3",
 pages        = "349--370",
 doi          = "10.1007/s11786-010-0027-4",
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@inproceedings(Helium,
 author       = "Bastiaan Heeren and Daan Leijen and Arjan van IJzendoorn",
 year         = "2003",
 title        = "Helium, for learning {H}askell",
 booktitle    = "Proceedings of the 2003 ACM SIGPLAN workshop on Haskell",
 series       = "Haskell '03",
 publisher    = "ACM",
 address      = "New York, NY, USA",
 pages        = "62--71",
 doi          = "10.1145/871895.871902",
)
@article(HuetZipper,
 author       = "G{\'e}rard Huet",
 year         = "1997",
 title        = "The Zipper",
 journal      = "Journal of Functional Programming",
 volume       = "7",
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 pages        = "549--554",
 doi          = "10.1017/S0956796897002864",
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@book(Hutton,
 author       = "Graham Hutton",
 year         = "2007",
 title        = "{Programming in Haskell}",
 publisher    = "Cambridge University Press",
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@incollection(cefp,
 author       = "Johan Jeuring and Alex Gerdes and Bastiaan Heeren",
 year         = "2012",
 title        = "A Programming Tutor for Haskell",
 editor       = "Vikt\'oria Zs\'ok and Zolt\'an Horv\'ath and Rinus Plasmeijer",
 booktitle    = "Central European Functional Programming School",
 series       = "Lecture Notes in Computer Science",
 volume       = "7241",
 publisher    = "Springer Berlin Heidelberg",
 pages        = "1--45",
 doi          = "10.1007/978-3-642-31374-5",
)
@article(Krishna,
 author       = "Aravind K. Krishna and Amruth N. Kumar",
 year         = "2001",
 title        = "A Problem Generator to Learn Expression: Evaluation in CSI, and Its Effectiveness",
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 volume       = "16",
 number       = "4",
 pages        = "34--43",
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@inproceedings(Kumar,
 author       = "Amruth N. Kumar",
 year         = "2005",
 title        = "Results from the Evaluation of the Effectiveness of an Online Tutor on Expression Evaluation",
 booktitle    = "Proceedings of the 36th SIGCSE Technical Symposium on Computer Science Education",
 series       = "SIGCSE '05",
 publisher    = "ACM",
 address      = "New York, NY, USA",
 pages        = "216--220",
 doi          = "10.1145/1047344.1047422",
)
@inproceedings(Lahtinen:novice,
 author       = "Essi Lahtinen and Kirsti Ala-Mutka and Hannu-Matti J\"{a}rvinen",
 year         = "2005",
 title        = "A Study of the Difficulties of Novice Programmers",
 booktitle    = "Proceedings of the 10th Annual SIGCSE Conference on Innovation and Technology in Computer Science Education",
 series       = "ITiCSE '05",
 publisher    = "ACM",
 address      = "New York, NY, USA",
 pages        = "14--18",
 doi          = "10.1145/1151954.1067453",
)
@inproceedings(Launchbury93anatural,
 author       = "John Launchbury",
 year         = "1993",
 title        = "A Natural Semantics for Lazy Evaluation",
 booktitle    = "Proceedings of the 20th ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages",
 series       = "POPL '93",
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 address      = "New York, NY, USA",
 pages        = "144--154",
 doi          = "10.1145/158511.158618",
)
@book(LearnYouAHaskell,
 author       = "Miran Lipovaca",
 year         = "2011",
 title        = "Learn You a Haskell for Great Good!: A Beginner's Guide",
 edition      = "1st",
 publisher    = "No Starch Press",
 address      = "San Francisco, CA, USA",
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@incollection(WHAT,
 author       = "Natalia L\'opez and Manuel N\'u\~nez and Ismael Rodr\'iguez and Fernando Rubio",
 year         = "2002",
 title        = "What: Web-Based Haskell Adaptive Tutor",
 editor       = "Donia Scott",
 booktitle    = "Artificial Intelligence: Methodology, Systems, and Applications",
 series       = "Lecture Notes in Computer Science",
 volume       = "2443",
 publisher    = "Springer Berlin Heidelberg",
 pages        = "71--80",
 doi          = "10.1007/3-540-46148-5\_8",
)
@misc(StepEval,
 author       = "Ben Millwood",
 year         = "2011",
 title        = "stepeval library: Evaluating a Haskell expression step-by-step",
 url          = "https://github.com/bmillwood/stepeval",
)
@article(JFP:rewriting,
 author       = "Thomas van Noort and Alexey Rodriguez Yakushev and Stefan Holdermans and Johan Jeuring and Bastiaan Heeren and Jos\'e Pedro Magalh\~aes",
 year         = "2010",
 title        = "A lightweight approach to datatype-generic rewriting",
 journal      = "Journal of Functional Programming",
 volume       = "20",
 pages        = "375--413",
 doi          = "10.1017/S0956796810000183",
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@mastersthesis(OlmerThesis,
 author       = "Tim Olmer",
 year         = "2014",
 title        = "Evaluation of Haskell expressions in a tutoring environment",
 school       = "Open Universiteit Nederland",
 url          = "http://hdl.handle.net/1820/5389",
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@book(RWH,
 author       = "Bryan O'Sullivan and John Goerzen and Don Stewart",
 year         = "2008",
 title        = "Real World Haskell",
 edition      = "1st",
 publisher    = "O'Reilly Media, Inc.",
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@article(Pareja-Flores:winhipe,
 author       = "Crist\'{o}bal Pareja-Flores and Jamie Urquiza-Fuentes and J. \'{A}ngel Vel\'{a}zquez-Iturbide",
 year         = "2007",
 title        = "WinHIPE: An IDE for Functional Programming Based on Rewriting and Visualization",
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@inproceedings(Rochel:2009:VL9:1929087.1929099,
 author       = "Jan Rochel",
 year         = "2010",
 title        = "The Very Lazy $\lambda $-calculus and the STEC Machine",
 booktitle    = "Proceedings of the 21st International Conference on Implementation and Application of Functional Languages",
 series       = "IFL'09",
 publisher    = "Springer-Verlag",
 address      = "Berlin, Heidelberg",
 pages        = "198--217",
 doi          = "10.1007/978-3-642-16478-1\_12",
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@inproceedings(Sestoft02demonstratinglambda,
 author       = "Peter Sestoft",
 year         = "2002",
 title        = "Demonstrating lambda calculus reduction",
 booktitle    = "The Essence of Computation: Complexity, Analysis, Transformation. Essays Dedicated to Neil D. Jones, number 2566 in Lecture Notes in Computer Science",
 publisher    = "Springer-Verlag",
 pages        = "420--435",
 doi          = "10.1007/3-540-36377-7\_19",
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@incollection(sparud:redex,
 author       = "Jan Sparud and Colin Runciman",
 year         = "1997",
 title        = "Tracing lazy functional computations using redex trails",
 editor       = "Hugh Glaser and Pieter Hartel and Herbert Kuchen",
 booktitle    = "Programming Languages: Implementations, Logics, and Programs",
 series       = "Lecture Notes in Computer Science",
 volume       = "1292",
 publisher    = "Springer Berlin Heidelberg",
 pages        = "291--308",
 doi          = "10.1007/BFb0033851",
)
@book(Thompson,
 author       = "Simon Thompson",
 year         = "2011",
 title        = "Haskell: The Craft of Functional Programming",
 edition      = "3rd",
 publisher    = "Addison-Wesley Longman Publishing Co., Inc.",
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@inproceedings(Vihavainen,
 author       = "Arto Vihavainen and Matti Paksula and Matti Luukkainen",
 year         = "2011",
 title        = "Extreme Apprenticeship Method in Teaching Programming for Beginners",
 booktitle    = "Proceedings of the 42Nd ACM Technical Symposium on Computer Science Education",
 series       = "SIGCSE '11",
 publisher    = "ACM",
 address      = "New York, NY, USA",
 pages        = "93--98",
 doi          = "10.1145/1953163.1953196",
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@inproceedings(VBT98,
 author       = "Eelco Visser and Zine-el-Abidine Benaissa and Andrew Tolmach",
 year         = "1998",
 title        = "Building Program Optimizers with Rewriting Strategies",
 booktitle    = "ICFP 1998: International Conference on Functional Programming",
 pages        = "13--26",
 doi          = "10.1145/289423.289425",
)