ghc-typelits-natnormalise: GHC typechecker plugin for types of kind GHC.TypeLits.Nat

[ bsd2, library, type-system ] [ Propose Tags ]

A type checker plugin for GHC that can solve equalities of types of kind Nat, where these types are either:

It solves these equalities by normalising them to sort-of SOP (Sum-of-Products) form, and then perform a simple syntactic equality.

For example, this solver can prove the equality between:

(x + 2)^(y + 2)

and

4*x*(2 + x)^y + 4*(2 + x)^y + (2 + x)^y*x^2

Because the latter is actually the SOP normal form of the former.

To use the plugin, add the

OPTIONS_GHC -fplugin GHC.TypeLits.Normalise

Pragma to the header of your file.


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Versions 0.1, 0.1.1, 0.1.2, 0.2, 0.2.1, 0.3, 0.3.1, 0.4, 0.4.1, 0.4.2, 0.4.3, 0.4.4, 0.4.5, 0.4.6, 0.5, 0.5.1, 0.5.2, 0.5.3, 0.5.4, 0.5.5, 0.5.6, 0.5.7, 0.5.8, 0.5.9, 0.5.10, 0.6, 0.6.1 (info)
Change log CHANGELOG.md
Dependencies base (>=4.9 && <5), ghc (>=8.0.1 && <8.6), ghc-tcplugins-extra (>=0.3), integer-gmp (==1.0.*), transformers (>=0.5.2.0 && <0.6) [details]
License BSD-2-Clause
Copyright Copyright © 2015-2016, University of Twente, 2017-2018, QBayLogic B.V.
Author Christiaan Baaij
Maintainer christiaan.baaij@gmail.com
Category Type System
Home page http://www.clash-lang.org/
Bug tracker http://github.com/clash-lang/ghc-typelits-natnormalise/issues
Source repo head: git clone https://github.com/clash-lang/ghc-typelits-natnormalise.git
Uploaded by ChristiaanBaaij at Tue May 8 23:09:33 UTC 2018
Distributions LTSHaskell:0.5.10, NixOS:0.6.1, Stackage:0.6.1, openSUSE:0.5.10
Downloads 5903 total (136 in the last 30 days)
Rating 2.25 (votes: 2) [estimated by rule of succession]
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Status Docs uploaded by user
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Readme for ghc-typelits-natnormalise-0.6.1

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ghc-typelits-natnormalise

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A type checker plugin for GHC that can solve equalities of types of kind Nat, where these types are either:

  • Type-level naturals
  • Type variables
  • Applications of the arithmetic expressions (+,-,*,^).

It solves these equalities by normalising them to sort-of SOP (Sum-of-Products) form, and then perform a simple syntactic equality.

For example, this solver can prove the equality between:

(x + 2)^(y + 2)

and

4*x*(2 + x)^y + 4*(2 + x)^y + (2 + x)^y*x^2

Because the latter is actually the SOP normal form of the former.

To use the plugin, add

{-# OPTIONS_GHC -fplugin GHC.TypeLits.Normalise #-}

To the header of your file.