Complete and decidable type inference for GADTs

Tom Schrijvers, Simon Peyton Jones, Martin Sulzmann, Dimitrios Vytiniotis
2009 Proceedings of the 14th ACM SIGPLAN international conference on Functional programming - ICFP '09  
GADTs have proven to be an invaluable language extension, a.o. for ensuring data invariants and program correctness. Unfortunately, they pose a tough problem for type inference: we lose the principal-type property, which is necessary for modular type inference. We present a novel and simplified type inference approach for local type assumptions from GADT pattern matches. Our approach is complete and decidable, while more liberal than previous such approaches.
doi:10.1145/1596550.1596599 dblp:conf/icfp/SchrijversJSV09 fatcat:pbnp54u5y5hlheywa6f7j4i42u