From adf753775394254435ccc6f6e0d029bb515aa093 Mon Sep 17 00:00:00 2001 From: Sergei Trofimovich Date: Tue, 19 Jan 2016 21:56:02 +0000 Subject: dev-haskell/psqueues: new package, a depend of dev-haskell/http2 Pure priority search queues. Package-Manager: portage-2.2.27 --- dev-haskell/psqueues/metadata.xml | 48 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) create mode 100644 dev-haskell/psqueues/metadata.xml (limited to 'dev-haskell/psqueues/metadata.xml') diff --git a/dev-haskell/psqueues/metadata.xml b/dev-haskell/psqueues/metadata.xml new file mode 100644 index 000000000000..d4c0b904bde1 --- /dev/null +++ b/dev-haskell/psqueues/metadata.xml @@ -0,0 +1,48 @@ + + + + haskell + + The psqueues package provides + <http://en.wikipedia.org/wiki/Priority_queue Priority Search Queues> in + three different flavors. + + * @OrdPSQ k p v@, which uses the @Ord k@ instance to provide fast insertion, + deletion and lookup. This implementation is based on Ralf Hinze's + <http://citeseer.ist.psu.edu/hinze01simple.html A Simple Implementation Technique for Priority Search Queues>. + Hence, it is similar to the + <http://hackage.haskell.org/package/PSQueue PSQueue> library, although it is + considerably faster and provides a slightly different API. + + * @IntPSQ p v@ is a far more efficient implementation. It fixes the key type + to @Int@ and uses a <http://en.wikipedia.org/wiki/Radix_tree radix tree> + (like @IntMap@) with an additional min-heap property. + + * @HashPSQ k p v@ is a fairly straightforward extension of @IntPSQ@: it + simply uses the keys' hashes as indices in the @IntPSQ@. If there are any + hash collisions, it uses an @OrdPSQ@ to resolve those. The performance of + this implementation is comparable to that of @IntPSQ@, but it is more widely + applicable since the keys are not restricted to @Int@, but rather to any + @Hashable@ datatype. + + Each of the three implementations provides the same API, so they can be used + interchangeably. The benchmarks show how they perform relative to one + another, and also compared to the other Priority Search Queue + implementations on Hackage: + <http://hackage.haskell.org/package/PSQueue PSQueue> + and + <http://hackage.haskell.org/package/fingertree-psqueue fingertree-psqueue>. + + <<http://i.imgur.com/KmbDKR6.png>> + + <<http://i.imgur.com/ClT181D.png>> + + Typical applications of Priority Search Queues include: + + * Caches, and more specifically LRU Caches; + + * Schedulers; + + * Pathfinding algorithms, such as Dijkstra's and A*. + + -- cgit v1.2.3-65-gdbad