Improve code coverage of the `bloomfilter` library

[jeltsch]

This issue calls for improving code coverage of the bloomfilter library.

A code coverage report was created by executing cabal test --enable-coverage lsm-tree:bloomfilter-tests on the main branch as of 2 April 2025, concretely on commit 441f194.

The individual coverage deficits of all modules in the bloomfilter library where examined. All non-trivial cases of missing coverage are listed below. Each case is described by either of the following:

• A situation that never occurred, which led to code not being executed
• A value that was never used (in which case the description contains the phrase “never used”)

Missing coverage of the following kinds is not mentioned here:

• Lack of coverage that follows from the program logic (impossible situations and unneeded values)
• Derived class instantiations
• Instantiations of NFData
• Field selectors
• Error message strings or parts thereof
• Explicit ()

Data.BloomFilter

• freeze
  • Never used
• thaw
  • Never used
• empty
  • Never used
• singleton
  • Never used
• elemHashes
  • Bit in Bloom filter not set
• length
  • Never used
• unfold
  • Never used

Data.BloomFilter.BitVec64

• prefetchIndex
  • Never used
• new
  • 128 or more words
• unsafeWrite
  • Bit to be cleared
• unsafeRead
  • Never used
• freeze
  • Never used
• thaw
  • Never used

Data.BloomFilter.Calc

• falsePositiveProb
  • Never used

Data.BloomFilter.Easy

• easyList
  • Empty set
• easyNew
  • Never used
• safeSuggestSizing
  • Non-positive expected maximum capacity
  • Expected maximum capacity too large
  • Invalid desired FPR
• primes
  • All above 1021 never used
• suggestSizing
  • Invalid expected maximum capacity
  • Invalid desired FPR

Data.BloomFilter.Hash

• hashSalt64 @ByteArray
  • Never used
• hashByteArray
  • Never used
• update @Word32
  • Never used
• update @Char
  • Never used
• makeHashes @RealHashes
  • Never used
• evalHashes @RealHashes
  • Never used
• Prim (CheapHashes a)
  • Never used
• indexLo
  • Never used
• indexHi
  • Never used

Data.BloomFilter.Internal

• (==) @(Bloom' h a)
  • Size divisible by 64
• Show (Bloom' h a)
  • Never used

Data.BloomFilter.Mutable

• new
  • No bits in filter
  • 2⁴⁸ − 1 or more bits in filter¹
• elem
  • Never used
• elemHashes
  • Never used
• length
  • Never used

Data.BloomFilter.Mutable.Internal

• Show (MBloom' s h a)
  • Never used

Footnotes

1. I actually wonder whether the corresponding guard should say > instead of >=, thus referring to 2⁴⁸ or more bits. ↩