Accompanying material for the paper "Generalizing Generalized Tries"
by Ralf Hinze, in Journal of Functional Programming, 10(4),
pp. 327-351, July 2000.

de Bruijn terms.

> module Term (
>     Term(Var, App, Lam),
>     Incr(Zero, Succ),
> ) where

> data Term v			=  Var v
>				|  App (Term v) (Term v)
>				|  Lam (Term (Incr v))
>				   deriving (Show)

> data Incr v			=  Zero | Succ v
>				   deriving (Show)