[Haskell-cafe] Haskell, Queries and Monad Comprehension

[Torsten Grust]

Hi Günther,

On May 25, 2010, at 21:37 , Günther Schmidt wrote:
> Hello Torsten,
> 
> well thank you for taking the time and answering that. It seems that the one thing I am good for, as far as contributions to this list go, is coaxing answers out of our Functional Pros. :)
> 
> That is good news then, I was getting frustrated reading fantastic papers which eventually were nothing more than teasers.
> 
> So, will Ferry then be usable from within Haskell?

Ferry is much more about the compilation of queries (over list-based
data models) than the invention of some new query syntax.  We
thus are mostly after embeddings of queries into existing 
host languages.  Such embeddings exist for

  -- C#    (Ferry-based LINQ to SQL)
  -- Links (new Ferry-based SQL code generator)
  -- Ruby  (in the works, provides a much richer and arguably more
            seamless embedding of queries over Ruby arrays as well
            as relational tables than does ARel or ActiveRevord's 
            find_by* methods).

There's some interesting connection between the compilation 
techniques employed by Ferry and Data Parallel Haskell.  
I talked to Simon Peyton Jones and he suggested to attempt 
a Haskell embedding.  So, Haskell: not yet.  But conceivable.

Cheers,
   --Torsten

> Am 25.05.10 21:28, schrieb Torsten Grust:
> > Günther,
> >
> > we are currently underway building the second version (as in:
> > done right this time) of Ferry, a query compiler that
> >
> > (1) accepts queries over ordered, nested lists,
> > (2) compiles these queries into an intermediate algebraic form, then
> > (3) emits (small bundles of) SQL queries that evaluate the input
> >      query over your off-the-shelf RDBMS.
> >
> > We've used Ferry's first version to build new LINQ to SQL providers
> > for Microsoft's LINQ as well as a new code generator for Phil Wadler's
> > Links.
> >
> > The Ferry compiler itself is built in Haskell.  Surf to www.ferry-lang.org
> > for more information, screencasts, papers, talks, and contact us for
> > more details.  We will be happy to share Ferry's Haskell code once in
> > digestable shape (soon).
> >
> > Cheers,
> >     --Torsten
> >
> > On May 24, 2010, at 03:20 , Günther Schmidt wrote:
> >> Hi all,
> >>
> >> is there anybody currently using Haskell to construct or implement a query language?
> >>
> >> I have read a couple of papers on "Monad Comprehension Calculus" and similar but none using Haskell nor any other existing programming language to build an actual implementation.
> >>
> >> Most papers give some sort of "Pseudo code", but I couldn't find any meat.
> >>
> >>
> >>
> >> Günther
> >>
> >> _______________________________________________
> >> Haskell-Cafe mailing list
> >> Haskell-Cafe at haskell.org
> >> http://www.haskell.org/mailman/listinfo/haskell-cafe
> >>
> >
> >
> 




-- 
  | Prof. Dr. Torsten Grust          torsten.grust at uni-tuebingen.de |
  |                              www-db.informatik.uni-tuebingen.de |
  |               Database Systems - Universität Tübingen (Germany) |