git.iko.soy/project-m36
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project-m36/examples/SimpleClient.hs
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1{-# LANGUAGE OverloadedStrings #-}
2import ProjectM36.Client
3import ProjectM36.TupleSet
4import ProjectM36.Atom
5import ProjectM36.Base
6import ProjectM36.Relation.Show.Term
8main :: IO ()
9main = do
10 -- 1. create a ConnectionInfo
11 let connInfo = RemoteProcessConnectionInfo "mytestdb" (createNodeId "127.0.0.1" defaultServerPort)
12 -- 2. conncted to the remote database
13 eConn <- connectProjectM36 connInfo
14 case eConn of
15 Left err -> putStrLn (show err)
16 Right conn -> do
17 --3. create a session on the "master" branch
18 eSessionId <- createSessionAtHead "master" conn
19 case eSessionId of
20 Left err -> putStrLn (show err)
21 Right sessionId -> do
22 --4. define a new relation variable with a DatabaseContext expression
23 let attrs = attributesFromList [Attribute "name" stringAtomType, Attribute "age" intAtomType]
24 mErr1 <- executeDatabaseContextExpr sessionId conn (Define "person" attrs)
25 putStrLn (show mErr1)
26 --5. add a tuple to the relation referenced by the relation variable
27 let (Right tupSet) = mkTupleSetFromList attrs [[stringAtom "Bob", intAtom 45]]
28 mErr2 <- executeDatabaseContextExpr sessionId conn (Insert "person" (MakeStaticRelation attrs tupSet))
29 putStrLn (show mErr2)
31 --6. execute a relational algebra query
32 let restrictionPredicate = AttributeEqualityPredicate "name" (NakedAtomExpr (stringAtom "Steve"))
33 eRel <- executeRelationalExpr sessionId conn (Restrict restrictionPredicate (RelationVariable "person"))
34 case eRel of
35 Left err -> putStrLn (show err)
36 Right rel -> putStrLn (show $ showRelation rel)
38 --7. close the connection
39 close conn