This package provides an implementation of the Adler-32 checksum algorithm. It supports a rolling checksum mode, i.e. the checksum of a sliding window of the input message can be computed efficiently. It also supports compounding, i.e. the checksum of the concatenation of two messages can be efficiently computed from the checksums of the two parts.
By default, the highly optimized implementation of Adler-32 from 'zlib' will be used. This can be disabled, in which case a pure haskell implementation will be used instead. On my system, the haskell version is 2 to 3 times slower.