A Design for Bidirectional Conversion between Blocks and Text for App Inventor

Blocks programming environments lower barriers to programming using visual code fragments that prevent syntactic and static semantic errors and reduce cognitive load. However, visual blocks notations can make programs more difficult to read, write, and share. Dual-mode environments that allow bidirectional conversion between isomorphic blocks and text representations can leverage the benefits of both modes. We are designing a dual-mode system for MIT App Inventor that supports textual representations for blocks, workspaces, screens, and whole projects. We present a preliminary design for Venbrace, a fully-braced textual syntax for App Inventor, based on a collection of design principles. Since a key principle is employing evidence-based programming language design, we will follow an iterative process that interleaves user studies with implementation. We describe planned user studies involving individuals of various levels of programming experience that test the usability of Venbrace and explore possible improvements.