The How to Design Programs (HtDP) curriculum [Felleisen et al. 2018], utilizing simple subsets of the Racket programming language, teaches the fundamentals of data-driven program design using the “design recipe”. This approach teaches recursion by structural decomposition of the input data, enough to express many algorithms on simple recursive data structures. Furthermore, this approach is deeply mechanical, having students write a “template” depending on the input type of the function that when filled in produces structurally-recursive programs.

We present a work-in-progress program synthesizer for the HtDP Student languages, Bingus, that utilizes the design recipe as its primary means of generating programs. By parsing the signature (specification in a comment) of a function, the first step of the design recipe, Bingus makes guesses depending on the signatures of the function inputs, utilizing the check-expects (unit tests) to determine when synthesis is complete.

We demonstrate usage of Bingus as a program synthesis tool integrated into the DrRacket IDE [Findler et al. 2002], and discuss ways that we plan to extend this tool for pedagogic purposes, such as providing better feedback to students from an auto-grader, or determining when student-provided unit tests are insufficient.