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Diffstat (limited to 'dev-haskell/hashtables/metadata.xml')
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1 files changed, 1 insertions, 98 deletions
diff --git a/dev-haskell/hashtables/metadata.xml b/dev-haskell/hashtables/metadata.xml index 86c607e5ac2e..6f84b90b37dc 100644 --- a/dev-haskell/hashtables/metadata.xml +++ b/dev-haskell/hashtables/metadata.xml @@ -3,107 +3,10 @@ <pkgmetadata> <maintainer type="project"> <email>haskell@gentoo.org</email> + <name>Gentoo Haskell</name> </maintainer> - <longdescription> - This package provides a couple of different implementations of mutable hash - tables in the ST monad, as well as a typeclass abstracting their common - operations, and a set of wrappers to use the hash tables in the IO monad. - - /QUICK START/: documentation for the hash table operations is provided in the - "Data.HashTable.Class" module, and the IO wrappers (which most users will - probably prefer) are located in the "Data.HashTable.IO" module. - - This package currently contains three hash table implementations: - - 1. "Data.HashTable.ST.Basic" contains a basic open-addressing hash table - using linear probing as the collision strategy. On a pure speed basis it - should currently be the fastest available Haskell hash table - implementation for lookups, although it has a higher memory overhead - than the other tables and can suffer from long delays when the table is - resized because all of the elements in the table need to be rehashed. - - 2. "Data.HashTable.ST.Cuckoo" contains an implementation of \"cuckoo - hashing\" as introduced by Pagh and Rodler in 2001 (see - <https://en.wikipedia.org/wiki/Cuckoo_hashing>). Cuckoo hashing has - worst-case /O(1)/ lookups and can reach a high \"load factor\", in which - the table can perform acceptably well even when more than 90% full. - Randomized testing shows this implementation of cuckoo hashing to be - slightly faster on insert and slightly slower on lookup than - "Data.Hashtable.ST.Basic", while being more space efficient by about a - half-word per key-value mapping. Cuckoo hashing, like the basic hash - table implementation using linear probing, can suffer from long delays - when the table is resized. - - 3. "Data.HashTable.ST.Linear" contains a linear hash table (see - <https://en.wikipedia.org/wiki/Linear_hashing>), which trades some insert - and lookup performance for higher space efficiency and much shorter - delays when expanding the table. In most cases, benchmarks show this - table to be currently slightly faster than @Data.HashTable@ from the - Haskell base library. - - It is recommended to create a concrete type alias in your code when using this - package, i.e.: - - > import qualified Data.HashTable.IO as H - > - > type HashTable k v = H.BasicHashTable k v - > - > foo :: IO (HashTable Int Int) - > foo = do - > ht <- H.new - > H.insert ht 1 1 - > return ht - - Firstly, this makes it easy to switch to a different hash table implementation, - and secondly, using a concrete type rather than leaving your functions abstract - in the HashTable class should allow GHC to optimize away the typeclass - dictionaries. - - This package accepts a couple of different cabal flags: - - * @unsafe-tricks@, default /ON/. If this flag is enabled, we use some - unsafe GHC-specific tricks to save indirections (namely @unsafeCoerce#@ - and @reallyUnsafePtrEquality#@. These techniques rely on assumptions - about the behaviour of the GHC runtime system and, although they've been - tested and should be safe under normal conditions, are slightly - dangerous. Caveat emptor. In particular, these techniques are - incompatible with HPC code coverage reports. - - * @sse41@, default /OFF/. If this flag is enabled, we use some SSE 4.1 - instructions (see <https://en.wikipedia.org/wiki/SSE4>, first available on - Intel Core 2 processors) to speed up cache-line searches for cuckoo - hashing. - - * @bounds-checking@, default /OFF/. If this flag is enabled, array accesses - are bounds-checked. - - * @debug@, default /OFF/. If turned on, we'll rudely spew debug output to - stdout. - - * @portable@, default /OFF/. If this flag is enabled, we use only pure - Haskell code and try not to use unportable GHC extensions. Turning this - flag on forces @unsafe-tricks@ and @sse41@ /OFF/. - - This package has been tested with GHC 7.0.3, on: - - * a MacBook Pro running Snow Leopard with an Intel Core i5 processor, - running GHC 7.0.3 in 64-bit mode. - - * an Arch Linux desktop with an AMD Phenom II X4 940 quad-core processor. - - * a MacBook Pro running Snow Leopard with an Intel Core 2 Duo processor, - running GHC 6.12.3 in 32-bit mode. - - Please send bug reports to - <https://github.com/gregorycollins/hashtables/issues>. - </longdescription> <use> <flag name="bounds-checking">if on, use bounds-checking array accesses</flag> <flag name="detailed-profiling">add detailed profiling information to profiled build-depends</flag> - <flag name="portable">if on, use only pure Haskell code and no GHC extensions.</flag> - <flag name="unsafe-tricks">turn on unsafe GHC tricks</flag> </use> - <upstream> - <remote-id type="github">gregorycollins/hashtables</remote-id> - </upstream> </pkgmetadata> |