Encoding Featherweight Java with Assignment and Immutability using The Coq Proof Assistant

We develop a mechanized proof of Featherweight Java with Assignment and Immutability in the Coq proof assistant. This is a step towards more machine-checked proofs of a non-trivial type system. We used object immutability close to that of IGJ [8]. We describe the challenges of the mechanization and the encoding we used inside of Coq. prover. Our Coq sources are publically available 1. Example. We define a parametrized class Cell, where the mutable instantiation can get and set the interned object, whereas the immutable instantiation can only get the interned object, provided initially in the constructor. We chose to use transitive mutability in this example. 1