A type and effect system for sharing

We outline a type and effect system which infers sharing possibly introduced by the evaluation of an expression. In this way, expressions get very expressive types, which generalize notions enforced in literature by type modifiers. Sharing is directly represented at the syntactic level as a relation among free variables, thanks to the fact that the underlying calculus is pure. That is, imperative features are modeled by just rewriting source code terms.