Lambdulus: teaching lambda calculus practically

Abstract

λ calculus is a great formal introduction to functional programming. However, its abstract nature poses a challenge for many students as they struggle both with the unfamiliarity of functional programming and with the high abstraction and minimalism of λ calculus. As a result, functional programming classes are often delayed to older students who are hoped to be better prepared for appreciating its qualities, as was the case at the authors’ university as well. 3 years ago, as part of a redesigned curriculum around programming languages education, we have decided to introduce students to various programming paradigms much sooner than before. In doing so, we faced the problem of explaining very theoretical foundational concepts to very young students in a very short time. We have monitored the achievements and shortcomings of the new course over the past years and as a result of our findings have developed Lambdulus, an interactive and visual evaluator of λ calculus expressions that encourages students to explore the mechanisms of λ calculus by treating it not as a theoretical concept, but as a programming language in its own right.