peano: Peano numbers

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Warnings:

'ghc-options: -O0' is not needed. Use the --disable-optimization configure flag.
These packages miss upper bounds: - tasty-bench Please add them, using `cabal gen-bounds` for suggestions. For more information see: https://pvp.haskell.org/

Lazy unary natural numbers.

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Properties

Versions	0.1.0.0, 0.1.0.1, 0.1.0.2, 0.1.0.2
Change log	CHANGELOG.md
Dependencies	base (>=4.9 && <5) [details]
License	BSD-3-Clause
Author	M Farkas-Dyck, Andreas Abel
Maintainer	Andreas Abel
Category	Data, Math
Source repo	head: git clone https://github.com/andreasabel/peano.hs
Uploaded	by AndreasAbel at 2023-10-23T09:21:52Z

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- Data.Peano

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peano-0.1.0.2.tar.gz [browse] (Cabal source package)
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Readme for peano-0.1.0.2

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peano - Lazy unary natural numbers

This package provides natural numbers in unary notation

data Peano
  = Zero
  | Succ Peano

implementing Num, Ord etc.

Purpose

One application is to check whether the length of a (potentially long) list is greater than a (small) number.

E.g., without optimization (-O 0),

genericLength (replicate (10 ^ 6) True) >= (5 :: Peano)

outperforms the same test for 5 :: Int by a factor of 10⁵, see benchmark:

  length
    Peano: OK
      450  ns ±  45 ns
    Int:   OK
      136  ms ± 4.1 ms