prelude-safeenum: A redefinition of the Prelude's Enum class in order to render it safe.
A redefinition of the Prelude's Enum class in order to render it safe. That is, the Haskell Language Report defines pred, succ, fromEnum, and toEnum to be partial functions when the type is Bounded, but this is unacceptable. We define a new type-class hierarchy for enumeration which is safe and also generalizes to cover types which can only be enumerated in one direction.
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| Versions [RSS] | 0.1.0, 0.1.0.1, 0.1.1, 0.1.1.1, 0.1.1.2, 0.1.1.3 |
|---|---|
| Change log | CHANGELOG |
| Dependencies | base (>=4 && <5) [details] |
| License | BSD-3-Clause |
| Copyright | Copyright (c) 2012–2021 wren gayle romano |
| Author | wren gayle romano |
| Maintainer | wren@cpan.org |
| Category | Prelude |
| Home page | https://wrengr.org/software/hackage.html |
| Bug tracker | https://github.com/wrengr/prelude-safeenum/issues |
| Source repo | head: git clone https://github.com/wrengr/prelude-safeenum.git |
| Uploaded | by WrenRomano at 2021-10-18T05:59:28Z |
| Distributions | LTSHaskell:0.1.1.3, NixOS:0.1.1.3, Stackage:0.1.1.3 |
| Reverse Dependencies | 2 direct, 0 indirect [details] |
| Downloads | 5345 total (20 in the last 30 days) |
| Rating | (no votes yet) [estimated by Bayesian average] |
| Your Rating | |
| Status | Docs available [build log] Last success reported on 2021-10-18 [all 1 reports] |
Readme for prelude-safeenum-0.1.1.3
[back to package description]prelude-safeenum
A redefinition of the Prelude's Enum class in order to render it
safe. That is, the Haskell Language Report defines pred, succ,
fromEnum, and toEnum to be partial functions when the type is
Bounded. This is unacceptable. We define a new type-class hierarchy
for enumeration which is safe and also generalizes to cover types
which can only be enumerated in one direction.
Install
This is a very simple package and should be easy to install. You should be able to use the standard:
$> cabal install prelude-safeenum
Portability
An attempt has been made to keep this library portable; however, it does rely on a few language extensions. All the required language extensions are:
- CPP
- GeneralizedNewtypeDeriving
- MagicHash - only for GHC
- Trustworthy - only for GHC >= 7.1
The GeneralizedNewtypeDeriving extension is used for brevity in Data.Number.CalkinWilf. If you'd like to use this package with a compiler that does not support that extension, contact the maintainer and it can be removed.
This package is only "Trustworthy" rather than "Safe" for two reasons: (1) Data.Number.CalkinWilf uses GeneralizedNewtypeDeriving, and (2) Prelude.SafeEnum imports GHC.Exts for build/foldr fusion and for the Char instances.