Abstract:
Inspired by Danvy, we describe a technique for defining, within
the Hindley-Milner type system, some functions which seem to require a
language with dependent types. We illustrate this by giving a general
definition of zipWith for which the Haskell library provides a family
of functions, each member of the family having a different type and arity.
Our technique consists in introducing ad hoc codings for natural numbers
which resemble numerals in 
-calculus
-calculusAvailable as PostScript, PDF, DVI.