Syntactic Completions with Material Obligations

Explore a 15-minute conference presentation from OOPSLA 2025 that introduces tall tylr, a revolutionary error-handling parser and editor generator designed to address the persistent problem of syntax errors in code editors. Learn how researchers from the University of Michigan developed a novel approach to syntactic completions that uses material obligations to abstract over multiple possible code completions, moving beyond the limitations of traditional syntax error recovery techniques like panic mode and multi-option repairs. Discover the innovative theory of tile-based parsing that underlies tall tylr, conceptually organized around a molder that transforms tokens into tiles and a melder that completes and parses tiles into terms using an error-handling generalization of operator-precedence parsing. Understand how the melding process is formalized through the meldr parsing calculus, which completes input tiles with additional obligations to ensure parsing into well-formed terms with guaranteed success over all inputs. Examine how tall tylr implements molding and completion-ranking using the principle of minimizing obligations, and explore the groundbreaking approach of materializing these syntactic obligations visually to programmers. Review the findings from a user study that evaluated the usability and utility of an editor that materializes syntactic obligations, revealing both positive outcomes and promising directions for future research in structure editing and error-handling parsing. Access comprehensive supporting materials including the full research article, supplementary archive with artifacts that have been evaluated as reusable with reproduced results, and detailed ORCID information for all contributing researchers from this ACM SIGPLAN-sponsored presentation at the OOPSLA2 2025 conference.