A proof-of-concept cabal solver example using SAT

Install the minisat binary to your PATH. http://minisat.se/MiniSat.html.
Edit the deps function in Cabal.hs so that the location of the cabal index tarball is the one on your system.
Run saveOpaleyeDeps to load the cabal index tarball, parse all the cabal files within, and save the dependencies that pertain to the opaleye package. This step is very slow (around 100 seconds on my machine) because I parse all cabal files at the start, rather than parsing them on demand. A fairly basic fix could speed up this stage a lot.
Run main to find the install plan for opaleye which requires the fewest dependent packages to be installed. This takes around 15 seconds on my machine. Speeding this up is work in progress.

ghci Main.hs
*Main> saveOpaleyeDeps
...
*Main> main
Looking for 0 <= num packages < 100
Looking for 0 <= num packages < 49
...

Please note that that the modules besides Cabal, Main and Solve are rather mysterious and should probably be ignored.

Name		Name	Last commit message	Last commit date
Latest commit History 10 Commits
Bisequence.hs		Bisequence.hs
Cabal.hs		Cabal.hs
Main.hs		Main.hs
README.md		README.md
SAT.hs		SAT.hs
Setup.hs		Setup.hs
Solve.hs		Solve.hs
VarMap.hs		VarMap.hs
solver-example.cabal		solver-example.cabal

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