# GTALib

A library for GTA programming https://bitbucket.org/emoto/gtalib

 Latest on Hackage: 0.0.6

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This package provides the core functionalities of the GTA (Generate, Test, and Aggregate) programming framework on Haskell (c.f., Kento Emoto, Sebastian Fischer, Zhenjiang Hu: Generate, Test, and Aggregate - A Calculation-based Framework for Systematic Parallel Programming with MapReduce. ESOP 2012: 254-273. The authors' version is available at http://www.ipl-lab.org/~emoto/ESOP2012.pdf).

Example

The following code is a GTA program to solve the 0-1 Knapsack problem (http://en.wikipedia.org/wiki/Knapsack_problem). It appears to be an exponential cost proram in the number of input items, because it appears to generate all item selections by `subsP items` (Generate), discard those with total weight heavier than the knapsack's capacity by `filterBy weightlimit capacity` (Test), and take the most valuable selection by `aggregateBy maxsumsolutionWith getValue` (Aggregate). However, it actually runs in a linear time owing to our proposed program transformation 'Filter-embedding Semiring Fusion' implemented in the library. In addition, it runs in parallel so that you can get linear speedup.

``````knapsack capacity items =
subsP items
`filterBy` weightlimit capacity
`aggregateBy` maxsumsolutionWith getValue

getValue (_, v) = v
getWeight (w, _) = w

weightlimit w = (<=w) <.> weightsum where
weightsum = homJ' times single nil
x1 `times` x2  = (   x1 +    x2) `min` (w+1)
single i  = getWeight i `min` (w+1)
nil = 0``````

Several examples of GTA programming are found in examples directory at https://bitbucket.org/emoto/gtalib/src.

Depends on 5 packages:
Used by 1 package: