system-f-agda
A formalization of the polymorphic lambda calculus extended with iso-recursive types
The code in this repository contains an Agda formalization of the Girard-Reynolds polymorphic lambda calculus (System F) extended with general recursion and iso-recursive types. The formalization includes two variants of an operational call-by-value semantics (small-step and big-step) with associated type soundness proofs, an equivalence proof of the two semantics, as well as proofs of decidability of type checking and uniqueness of typing derivations.
The file src/README.agda contains a more detailed overview of the
formalization.
Verifying the formalization
The formalization is written in Agda and makes heavy use of the Agda standard library. The code in this repository has been verified using Agda 2.5.3 and version 0.14 of the standard library. The latest versions of the Agda distribution and standard library, along with setup instructions, can be found at
The easiest way to verify all the code is to compile the README.agda
file from the src/ directory. Run
agda src/README.agda -i src -i <path-to-Agda-standard-library>/src
in the console, or simply open the file in the
Agda Emacs mode
and type C-c C-l.
Using the Emacs mode one can also run Agda functions interactively in
Emacs by typing C-x C-n <expression>. For example, typing
C-x C-n typeOf [] (Λ (λ' (var zero) (var zero)))
in the module SystemF.TypeCheck runs the type-checking decision
procedure to determine the type of the polymorphic identity function.
It should return
yes (∀' (var zero →' var zero) , Λ (λ' (var zero) (var zero)))
Source code
The Agda sources of the formalization are freely available on GitHub:
License and copyright
See the LICENSE file.
Sandro Stucki -- Copyright (c) 2015 EPFL