ghc-typenats-bits (empty) → 0.1.0

raw patch · 5 files changed

+132/−0 lines, 5 filesdep +base

Dependencies added: base

Files

CHANGELOG.md +4/−0
LICENSE +20/−0
README.md +17/−0
ghc-typenats-bits.cabal +48/−0
src/GHC/TypeNats/Bits.hs +43/−0

+ CHANGELOG.md view

@@ -0,0 +1,4 @@+## 0.1.0 (2026-09-14)+Initial release.++- `ShiftL`, `ShiftR`, `Xor`

+ LICENSE view

@@ -0,0 +1,20 @@+Copyright (c) 2026 Ben Orchard (@raehik) <thefirstmuffinman@gmail.com>++Permission is hereby granted, free of charge, to any person obtaining+a copy of this software and associated documentation files (the+"Software"), to deal in the Software without restriction, including+without limitation the rights to use, copy, modify, merge, publish,+distribute, sublicense, and/or sell copies of the Software, and to+permit persons to whom the Software is furnished to do so, subject to+the following conditions:++The above copyright notice and this permission notice shall be included+in all copies or substantial portions of the Software.++THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.+IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,+TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE+SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

+ README.md view

@@ -0,0 +1,17 @@+# ghc-typenats-bits+Do you feel sad at the lack of bitwise functions for Haskell type-level natural+numbers? Me too. It's OK. Please enjoy this library. Includes such classics as:++- left shift+- logical right shift+- XOR++## Why?+[hackage-type-level-prng]: https://hackage.haskell.org/package/type-level-prng++I need these definitions in multiple libraries (e.g.+[type-level-prng][hackage-type-level-prng], a WIP generics lib), and they appear+to have gone undefined on Hackage.++## License+Provided under the MIT license. See `LICENSE` for license text.

+ ghc-typenats-bits.cabal view

@@ -0,0 +1,48 @@+cabal-version: 1.12++-- This file has been generated from package.yaml by hpack version 0.38.2.+--+-- see: https://github.com/sol/hpack++name:           ghc-typenats-bits+version:        0.1.0+synopsis:       Bitwise operations on type-level natural numbers+description:    Provides extra bitwise operations on type-level 'GHC.TypeNats.Natural's, comparable to the functions in "Data.Bits".+category:       Types, Data+homepage:       https://github.com/raehik/ghc-typenats-bits#readme+bug-reports:    https://github.com/raehik/ghc-typenats-bits/issues+author:         Ben Orchard+maintainer:     Ben Orchard <thefirstmuffinman@gmail.com>+license:        MIT+license-file:   LICENSE+build-type:     Simple+tested-with:+    GHC==9.14+  , GHC==9.12+  , GHC==9.10+extra-source-files:+    README.md+    CHANGELOG.md++source-repository head+  type: git+  location: https://github.com/raehik/ghc-typenats-bits++library+  exposed-modules:+      GHC.TypeNats.Bits+  other-modules:+      Paths_ghc_typenats_bits+  hs-source-dirs:+      src+  default-extensions:+      NoStarIsType+      DerivingVia+      DeriveAnyClass+      DefaultSignatures+      TypeFamilies+      MagicHash+  ghc-options: -fhide-source-paths -Wall -Winvalid-haddock+  build-depends:+      base >=4.20 && <5+  default-language: GHC2024

+ src/GHC/TypeNats/Bits.hs view

@@ -0,0 +1,43 @@+{-# LANGUAGE UndecidableInstances #-}++-- | Type-level "Data.Bits" definitions, over GHC opaque type-level 'Natural's.++module GHC.TypeNats.Bits+  ( type ShiftL+  , type ShiftR+  , type Xor+  ) where++import GHC.TypeNats+import GHC.TypeError qualified as TE++-- | Left shift.+type ShiftL x i = x * 2^i++-- | Logical right shift.+type ShiftR x i = x `Div` 2^i++-- | The exclusive or of the binary representation of two 'Natural's.+type Xor n m = XorLoop 1 0 n m++-- calculates one binary digit at a time, so should be O(log n) with value...+-- but with a very high constant factor (8 ops, 2 pattern matches).+-- I would love to compute this more efficiently!+type family XorLoop factor acc n m where+  XorLoop factor acc 0 0 = acc+  XorLoop factor acc n m =+    XorLoop+      (factor*2)+      (acc + factor * (((n `Mod` 2) `BitXor` (m `Mod` 2))))+      (n `Div` 2)+      (m `Div` 2)++-- | Exclusive or on two "bit" 'Natural's.+--+-- Both 'Natural's must be either 0 or 1, or it emits a type error.+type family BitXor n m where+  BitXor 0 0 = 0+  BitXor 0 1 = 1+  BitXor 1 0 = 1+  BitXor 1 1 = 0+  BitXor n m = TE.TypeError (TE.Text "BitXor: got non-bit Naturals")