HyloDP

A package for solving dynamic programming problems in Haskell

Introduction

This package contains the library HyloDP and six solved DP problems: Edit Distance, Fibonacci, Knapsack, Longest Common Subsequence, Random Walk and Text Segmentation.

This package contains the code of the research article: Software: Practice and Experience (ISSN:1097-024X)

"Easily solving dynamic programming problems in Haskell by memoization of hylomorphisms" by D.Llorens and J.M. Vilar. Software: Practice and Experience (ISSN:1097-024X). 2020; 50: 2193–2211. [https://doi.org/10.1002/spe.2887](https://doi.org/10.1002/spe.2887).

A preliminary version of the paper can be downloaded from here.

The core ideas are:

• Using hylomorphisms as generic control flow mechanism.

• Adding memoization to avoid recomputation of intermediate results.

• Modelling the composition of solutions by means of semirings.

• Using dispatch by result type as a simple way to decide the kind of answer desired (e.g. the best solution, the score of that solution, or the total number of solutions.)

A problem is described by an instance of DPProblem and solved by using dpSolve. See the documentation of HyloDP.Base for an example.

Contents

• The library is contained in the src directory.
• The test directory contains several HSpec tests.
• There are six examples in the examples directory.
• The run-examples.sh script runs all the examples.
• This library is implemented as a package on Hackage.