Stephen Dolan has curated a comprehensive collection of counterexamples in type systems, featuring 31 distinct scenarios that expose limitations in programming language design. The resource includes contributions from Andrej Bauer, Leo White, and Jeremy Yallop, making it a collaborative effort spanning polymorphic references to Curry's paradox.

These counterexamples illuminate fundamental challenges in type theory that affect language implementers and compiler designers. Each entry reveals edge cases where type systems break down, from covariant containers to runtime type misinformation, providing concrete examples of theoretical concepts in practice.

The collection serves as an essential reference for programming language researchers and developers building type checkers, compilers, or exploring advanced type features. Rather than abstract theory, these examples offer immediate practical value for anyone designing or debugging systems with complex type relationships.