Hazel features typed holes in the text, allowing users to typecheck, manipulate, and run programs even when they are syntactically malformed. This work was published in the 2022 ACM SIGPLAN International Symposium on New Ideas, New Paradigms, and Reflections on Programming and Software. Users could manipulate the code explanations and syntactic forms displayed to them. We studied the depth and the explanations’ level of granularity, which the participants found helpful. The tool is in the current version of Hazel and was used in at least one iteration of teaching the undergraduate programming languages course at the University of Michigan. 

Collaborators: Hannah Potter, Cyrus Omar, René Just