Package: ghc-bitvec (1.1.5.0-bp160.1.13)

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.