On Wed, Sep 24, 2008 at 11:17:01PM +0200, Manlio Perillo wrote:
Hi.
I need a simple, concurrent safe, database, written in Haskell. A database with the interface of Data.Map would be great, since what I need to to is atomically increment some integer values, and I would like to avoid to use SQLite.
I've tried writing at least part of that. But it's still higly experimental and uses template haskell. It looks like this: from that some datastructures are defined which look like tables used in traditional RDBMS such as SQLite.. However if you don't want to use many "tables" you may be a lot faster writing down what you need yourself. My lib automacially generates code for inserting / deleting tuples into multi indexes such as (Map Int (Map Int PrimIdx)). $(let cds = defaultTable { tblName = "cds" , columns = [ ("cdId", conT ''Int) , ("title", conT ''Int) ] , primary = PrimaryUniq [ "cdId" ] [| 0 |] , indexes = [ Index "title" [] ] , tblStates = [ ( "nextCdId", [t| Int |], [| 0 |] ) ] } tracks = let a="a" -- updateNumRows n = [| \n -> cdUpdateByPK (\r -> r { num_tracks = (num_tracks r) + $(n) } ) |] in defaultTable { tblName = "tracks" , columns = [ ("trackId", conT ''Int ) , ("name", conT ''String) , ("cd", conT ''Int) -- foreign key ] , primary = PrimaryUniq [ "cd", "trackId" ] [| 0 |] , indexes = [ Index "cd" [ IndexUnique "trackId" ] ] --the id is uniq foreach cd -- checks = [ foreignConstraint "cd" "cds" "id" ] -- triggers = [ InsertUpdate (Just ["cd"]) [| cdUpdateByPK ( updateNum_tracks (+1) ) . pk |] -- DeleteUpdate (Just ["cd"]) [| cdUpdateByPK ( updateNum_tracks (-1) ) . pk |] -- ] } db = defaultDB { dbName = "my" , tables = [ cds, tracks] , statistics = True } in createDB db) If you're interested drop me a mail. Marc