Names For Free - Polymorphic Views of Names and Binders

• We propose a novel technique to represent names and binders inHaskell. The dynamic (run-time) representation is based on de Bruijnindices, but it features an interface to write and manipulatevariables conviently, using Haskell-level lambdas and variables. Thekey idea is to use rich types: a subterm with an additional free variableis viewed either as $\forall v. v \rightarrow \mathsf{Term} (a + v)$or $\exists v. v \times \mathsf{Term} (a + v)$ depending on weather itis constructed or analysed. We demonstrate on a number of exampleshow this approach approach permits to express terms construction and manipulation in a natural way, while retaining the good properties ofrepresentations based on de Bruijn indices.

Ämnesord

NATURVETENSKAP  -- Data- och informationsvetenskap -- Datavetenskap (hsv//swe)

NATURAL SCIENCES  -- Computer and Information Sciences -- Computer Sciences (hsv//eng)

Nyckelord

type-classes

polymorphism

name binding

parametricity

nested types

Publikations- och innehållstyp

kon (ämneskategori)

ref (ämneskategori)