On the undecidability of partial polymorphic type reconstruction
School of Computer Science; Carnegie Mellon University
Pittsburgh, PA 15213
We prove that partial type reconstruction for the pure polymorphic *-calculus is undecidable by a reduction from the second-order unification problem, extending a previous result by H.-J. Boehm. We show further that partial type reconstruction remains undecidable even in a very small predicative fragment of the polymorphic *-calculus, which implies undecidability of partial type reconstruction for * ML as introduced by Harper, Mitchell, and Moggi.