Smells in block-based programming languages

Code smells were originally designed for object-oriented code, but in recent years, have been applied to end-user languages, including spreadsheets and Yahoo! Pipes. In this paper, we explore code smells in block-based end-user programming languages aimed at education. Specifically, we explore the occurrence of smells in two educational languages not previously targeted by smell detection and refactoring research: LEGO MINDSTORMS EV3 and Microsoft's Kodu. The results of this exploration show that object-oriented-inspired smells indeed occur in educational end-user languages and are present in 88% and 93% of the EV3 and Kodu programs, respectively. Most commonly we find that programs are plagued with lazy class, duplication, and dead code smells, with duplication smells being present in nearly two-thirds of programs in both languages.