GeckoGraph: A visual language for polymorphic types

Polymorphic type is an important feature in most strongly typed programming languages. They allow functions to be written in a way that can be used with different data types, while still enforcing the relationship and constraints between the values. However, programmers often find polymorphic types difficult to use and understand, and tend to reason in terms of concrete types. We propose GeckoGraph, a graphical notation for types. GeckoGraph aims to complement traditional text-based type notation by making reading, understanding, and comparing types easier. We conducted a large-scale user study comparing GeckoGraph to text-based type notation. To our knowledge, this is the largest controlled user study on functional programming ever conducted. The results show no overall significant differences in task completion time or success rate. However, we observed a modest improvement in success rate among beginner participants. For the most challenging task, GeckoGraph improved success rates by 14.5% for beginners and 11.2% for less experienced users. These findings suggest that GeckoGraph has potential as a teaching and learning aid for polymorphic type systems.