Evaluation of Haskell expressions in a tutoring environment

Students that follow an introduction course in functional programming often face difficulties in understanding the evaluation steps of an expression. Inspecting and practicing with the evaluation steps of a Haskell expression can help students in better understanding these evaluation steps. In fact, the stepwise evaluation of expressions can be used to explain programming concepts such as recursion, higher-order functions, pattern matching and lazy evaluation. This thesis describes how students in a tutoring environment can be supported to understand evaluation strategies and programming concepts using the evaluation steps of Haskell expressions. A prototype has been developed of a step-wise evaluator for Haskell expressions. The prototype supports multiple evaluation strategies and besides inspecting the evaluation steps it is possible to practice with evaluation steps and to get feedback. The prototype uses the IDEAS framework, which is a generic framework for rewriting terms, to rewrite expressions. The decision to rewrite a certain sub expression depends on the evaluation strategy and the function definitions. The hypothesis that the developed prototype can provide students with a better understanding of important programming concepts in the functional programming paradigm is supported by a qualitative research that has been executed under teachers and students