finitary-optics: Prisms and Isos between finitary types.

[ data, gpl, library ] [ Propose Tags ]

Provides convenience optics for working with finitary types. Specifically gives an Iso for inter-converting between types of the same cardinality, and a Prism for inter-converting between types of different cardinalities.

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Dependencies base (>=4.12 && <5), finitary (>= && <2.2), finite-typelits (>= && <0.2), optics-core (==0.3.*) [details]
License GPL-3.0-or-later
Copyright (C) Koz Ross 2019
Author Koz Ross
Maintainer Sam Derbyshire
Revised Revision 2 made by sheaf at 2021-02-09T19:25:13Z
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Uploaded by koz_ross at 2020-06-06T00:02:31Z
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What's this all about, then?

If a type has an instance of Finitary, we know the type's cardinality n, and can convert any (non-bottom) inhabitant to a value of Finite n. We can use this to inter-convert between these types. This can sometimes be useful.

This library provides some optics (specifically a Prism and an Iso) which help us do this kind of conversion more conveniently.

Sounds good! Can I use it?

We've tested this library on GHCs 8.6.5, 8.8.3 and 8.10.1, on GNU/Linux x86_64. If you use this library on any other platforms, let us know how it goes - especially if something breaks!


This library is under the GNU General Public License, version 3 or later (SPDX code GPL-3.0-or-later). For more details, see the file.