[Haskell-cafe] Feedback/Ideas for a Master Thesis about creating a Querying Tool for Hackage

Duncan Coutts duncan.coutts at googlemail.com
Fri Apr 11 15:19:38 UTC 2014

On Thu, 2014-03-27 at 18:51 +0100, Victor Nithander wrote:
> Hi,
> My name is Victor Nithander and I am currently doing my Master Thesis at
> the Computer Science and Engineering department at Chalmers in Gothenburg
> and would like to ask you for some help.
> My Master Thesis is about creating a querying tool for Hackage written in
> Haskell and I would like to know what kind of features you would like the
> querying tool to have. My plan is to design and implement an embedded
> language for queries to be expressed in and then implement a backend which
> accordingly takes care of those queries. I then plan to packet the tool as
> a package using Cabal and upload it to Hackage.

Hi Victor,

This sounds great. Some feedback:

I can't quite tell from your description if you're planning to query
just the package metadata (ie the info available in the hackage index)
or also the content / source code of packages. Just using the metadata
would be a lot easier!

Something you may or may not wish to consider is full text search. I've
actually been considering integrating full text search into the
cabal-install client (based on the text search code that the
hackage-server uses). I'm not quite sure if that'd fit nicely with the
kind of structured querying that you've mentioned or not. Something to
consider anyway.

Making it into it's own package is certainly the right place to start.
You may want to keep in mind however two contexts where one may
ultimately wish to use the code: hackage-server and cabal-install.
Assuming that you're only using the index metadata and not package
contents then this could fit nicely with either of these tools. In
hackage-server we'd be somewhat concerned about performance, but would
be able to keep data structures in memory. In cabal-install we obviously
cannot pre-compute an in-memory structure for multiple queries, but it
would be possible to pre-compute some structure and keep it on disk, and
load it into memory to do a single query (a bit like how hoogle works


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