Security type error diagnosis for higher-order, polymorphic languages

•Combines type error slicing with type error diagnosis heuristics.•Source language is higher-order and parametrically polymorphic.•Features tailored heuristics to deal with parametricity.•Features tailored heuristics for dealing with dependency based analyses.•A working implementation in Haskell is available.

We combine the type error slicing and heuristics based approaches to type error diagnostic improvement within the context of type based security analysis on a let-polymorphic call by value lambda calculus extended with lists, pairs and the security specific constructs declassify and protect. We define and motivate four classes of heuristics that help diagnose inconsistencies among the constraints, and show their effect on a selection of security incorrect programs.