Re: [Haskell-cafe] Expression problem in the database?
Hi Manuel, On 22 Jul 2013, at 21:00, Manuel Gómez wrote (with possible deletions): > Hi café, > > I don’t know whether this is a good forum to ask about this —perhaps > Stack Overflow is better suited—, but since Haskell and related > languages are so finely fit for good solutions to the expression > problem, I figure this list may have a few helpful pointers regarding > this problem. [...] are you merely seeking for a relational encoding of Boolean expressions or do you plan to also operate on these expression (e.g., evaluate, simplify, normalize) inside the database? Cheers, --Torsten -- | Prof. Dr. Torsten Grust | Database Systems — Universität Tübingen (Germany) | torsten.gr...@uni-tuebingen.de | db.inf.uni-tuebingen.de ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell, Queries and Monad Comprehension
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@haskell.org > >> http://www.haskell.org/mailman/listinfo/haskell-cafe > >> > > > > > -- | Prof. Dr. Torsten Grust torsten.gr...@uni-tuebingen.de | | www-db.informatik.uni-tuebingen.de | | Database Systems - Universität Tübingen (Germany) | ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell, Queries and Monad Comprehension
Günther, 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. 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 -- | Prof. Dr. Torsten Grust torsten.gr...@uni-tuebingen.de | | www-db.informatik.uni-tuebingen.de | | Database Systems - Universität Tübingen (Germany) | ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] is anyone familiar with "Comprehending Queries" by Torsten Grust?
Günther, feel free to contact me when it comes to questions regarding ``Comprehending Queries.'' Understanding database queries as (specific) functional programs is far from being an obsolete endeavor. Quite the contrary. Think LINQ (Microsoft) or Links (Philip Wadler). Or Kleisli (Limsoon Wong). Or monoid comprehensions (Leo Fegaras). Or Ferry (my group at U Tübingen) [1]. Cheers, --Torsten (no `h' in here ;-) [1] http://www.ferry-lang.org/ On Mar 28, 2010, at 16:04 , Günther Schmidt wrote: > Hi all, > > is anyone here familiar with the paper "Comprehending Queries" by Thorsten > Grust? http://kops.ub.uni-konstanz.de/volltexte/1999/312/pdf/312_1.pdf > > As the paper dates from 1999 I wonder if its content may have been > "obsoleted" by later works or if it still is pretty much current. > > I ask this because I'm still struggling to put my program with lots of > queries on a more sound code base. > > Günther > > > ___ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > -- | Prof. Dr. Torsten Grust torsten.gr...@uni-tuebingen.de | | www-db.informatik.uni-tuebingen.de | | Database Systems - Universität Tübingen (Germany) | ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: OT: Literature on translation of lambda calculus to combinators
Dear all, Dušan Kolář fit.vutbr.cz> writes: > [...] > Could anyone provide a link to some paper/book (electronic version of > both preferred, even if not free) that describes an algorithm of > translation of untyped lambda calculus expression to a set of > combinators? Preferably SKI or BCKW. I'm either feeding google with > wrong question or there is no link available now... 13 years ago (ugh...) I've posted a tutorial-style treatment of the compilation of Dave Turner's SASL to SKI. Also addresses reduction and simple optimizations of the resulting SKI programs. http://www-db.informatik.uni-tuebingen.de/files/publications/sasl.ps.gz Cheers, —Torsten ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
