fin: Nat and Fin: peano naturals and finite numbers

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This package provides two simple types, and some tools to work with them. Also on type level as DataKinds.

-- Peano naturals
data Nat = Z | S Nat

-- Finite naturals
data Fin (n :: Nat) where
    Z :: Fin ('S n)
    S :: Fin n -> Fin ('Nat.S n)

vec implements length-indexed (sized) lists using this package for indexes.

The Data.Fin.Enum module let's work generically with enumerations.

See Hasochism: the pleasure and pain of dependently typed haskell programming by Sam Lindley and Conor McBride for answers to how and why. Read APLicative Programming with Naperian Functors by Jeremy Gibbons for (not so) different ones.

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Versions 0, 0.0.1, 0.0.2, 0.0.3, 0.1, 0.1, 0.1.1, 0.2
Change log
Dependencies base (>=4.7 && <4.13), bifunctors (>=5.5.3 && <5.6), dec (>=0.0.3 && <0.1), deepseq (>= && <1.5), hashable (>= && <1.4), nats (>=1.1.2 && <1.2), semigroups (>=0.18.4 && <0.20), void (>=0.7.2 && <0.8) [details]
License BSD-3-Clause
Copyright (c) 2017-2019 Oleg Grenrus
Author Oleg Grenrus <>
Maintainer Oleg.Grenrus <>
Category Data, Dependent Types, Singletons
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Source repo head: git clone
Uploaded by phadej at 2019-07-07T11:14:12Z




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