BSD-3-Clause licensed by Alex Washburn
Maintained by [email protected]
This version can be pinned in stack with:bv-little-1.3.2@sha256:a1bd7f3dbb8dae48f2a1e8bf5e7c98eaa8fced338cbb72b2ec3f74b1100eb3df,6288

Module documentation for 1.3.2

Depends on 2 packages(full list with versions):
Used by 1 package in nightly-2024-07-17(full list with versions):

Efficient little-endian bit vector Haskell library

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This package contains an efficient implementation of little-endian, immutable bit vectors. It implements most applicable type-classes and also conversions to and from signed or unsigned numbers.

For an implementation of big-endian, immutable bit vectors, use the bv package.

For an implementation of little-endian, mutable bit vectors, use the bitvec package.

Accessing type-class instances

This package utilizes the “multiple sub-libraries” feature of Cabal. The intended usage is an “opt-in” dependency footprint for the bv-little package, as not all type-class instances which are defined are exposed by default. Therefore package consumers can select which, if any, type-class instances outside of the core libraries they wish to have exposed and transitively depend on the associated package(s).

New type-class instance exposure procedure:

  1. All BitVector instances of type-classes defined in base are exported by default from the Data.BitVector.LittleEndian module.

  2. Each BitVector instance of a type-class defined in a package other than base is exposed through a specific sub-library dependency and a special exposing module.

To access an instance of a type-class defined outside base, add the requisite sub-library to your build-depends and import the corresponding exposing module within your code-base.

Sub-library Dependency Exposing Module Type-class Instance(s)
bv-little:instances-binary Data.BitVector.LittleEndian.Binary Binary
bv-little:instances-mono-traversable Data.BitVector.LittleEndian.MonoTraversable MonoFoldableMonoFunctorMonoTraversable
bv-little:instances-mono-traversable-keys Data.BitVector.LittleEndian.MonoKeyed MonoAdjustableMonoFoldableWithKeyMonoIndexableMonoKeyedMonoLookupMonoTraversableWithKeyMonoZipMonoZipWithKey
bv-little:instances-quickcheck Data.BitVector.LittleEndian.QuickCheck ArbitraryCoArbitrary
bv-little:instances-text-show Data.BitVector.LittleEndian.TextShow TextShow


The test suite ensures that all type-class instances are “lawful” and that data-structure–specific functionality is well defined.

The TestSuite.hs file contains the specification. It can be run by invoking any of the following commands:

  • cabal test

  • stack test


The benchmarks provide an empyrical check for the asymptotic complexity of data structure operations and also provide easy metrics for detecting performance regressions.

The Benchmarks.hs file contains these metrics. It can be run by invoking any of the following commands:

  • cabal bench

  • stack bench


bv-little follows semantic versioning (SemVer).


  • Updating dependency upper bounds


  • Fixed Haddock documentation rendering in sub-libraries


  • Added back TextShow instance

  • Added specializations

  • Dropping support for GHC < 9.2.3


  • Restructuring library to expose instances in a refined, “opt-in” manner

  • Dropped support for GHC < 8.8.1

  • Added Binary instance

  • Added Read instance


  • Added more benchmarks

  • Updated test suite to be more reliable


  • Added rank and select functions


  • Correcting Eq instance to test for value equality and not construction equality

  • Updated unit tests do not fail when the antecedent of logical implication cannot be satisfied


  • Added explicit recursion to monomorphic folds to improve time and space performance

  • Added the following instances:

    • MonoAdjustable
    • MonoFoldableWithKey
    • MonoIndexable
    • MonoKeyed
    • MonoLookup
    • MonoTraversableWithKey
    • MonoZip
    • MonoZipWithKey
    • TextShow
  • Updated the following functions to be constant time:

    • omap
    • olength64
    • oall
    • oany
    • ofoldr1Ex
    • ofoldl1Ex
    • oelem
    • onotElem
    • ozipWith


  • Updating to base bounds for GHC 8.6.1


  • Updated to well-typed internal representation

  • Corrected defect in rotate, rotateL, and rotateR

  • Improved performance by switching exponentiation with base 2 to bit shifting operations

  • Improved performance of clearBit by increasing strictness

  • Increased benchmark coverage

  • Increased test suite coverage


  • Created instances of applicable typeclass instances

  • Added numeric conversion functions

  • Added basic test suite

  • Added stub benchmark