ghc-bitvec

A newtype over 'Bool' with a better 'Vector' instance: 8x less memory, up to
3500x faster.
The <https://hackage.haskell.org/package/vector vector> package represents
unboxed arrays of 'Bool's spending 1 byte (8 bits) per boolean. This library
provides a newtype wrapper 'Bit' and a custom instance of an unboxed 'Vector',
which packs bits densely, achieving an 8x smaller memory footprint. The
performance stays mostly the same; the most significant degradation happens for
random writes (up to 10% slower). On the other hand, for certain bulk bit
operations 'Vector' 'Bit' is up to 3500x faster than 'Vector' 'Bool'.
=== Thread safety

"Data.Bit" is faster, but writes and flips are not thread-safe. This is

because naive updates are not atomic: they read the whole word from memory,
then modify a bit, then write the whole word back. Concurrently modifying
non-intersecting slices of the same underlying array may also lead to
unexpected results, since they can share a word in memory. *
"Data.Bit.ThreadSafe" is slower (usually 10-20%), but writes and flips are
thread-safe. Additionally, concurrently modifying non-intersecting slices of
the same underlying array works as expected. However, operations that affect
multiple elements are not guaranteed to be atomic.
=== Similar packages

<https://hackage.haskell.org/package/bv bv> and

<https://hackage.haskell.org/package/bv-little bv-little> do not offer mutable
vectors.

<https://hackage.haskell.org/package/array array> is memory-efficient for

'Bool', but lacks a handy 'Vector' interface and is not thread-safe.

          

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License: BSD-3-Clause
URL: https://hackage.haskell.org/package/bitvec