basic API for query engines

haskell-experiments/src/Datalog/NaiveQE.hs

@@ -4,5 +4,32 @@
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# OPTIONS_GHC -Wno-unrecognised-pragmas #-}
 {-# LANGUAGE BlockArguments #-}
+{-# HLINT ignore "Redundant flip" #-}
+{-# LANGUAGE ImportQualifiedPost #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# OPTIONS_GHC -Wno-unrecognised-pragmas #-}
+{-# LANGUAGE InstanceSigs #-}
+{-# LANGUAGE BlockArguments #-}
 
 module Datalog.NaiveQE where
+import Datalog.QueryEngine
+import Data.Text
+import Datalog.DatalogDB
+import Datalog.DatalogParser
+import Control.Exception
+
+data NaiveQE = NaiveQE 
+  {
+
+  } deriving (Show, Eq)
+
+instance QueryEngine NaiveQE where
+  queryEngine :: (DatalogDB db) => db -> NaiveQE
+  queryEngine db = NaiveQE { }
+  query :: NaiveQE -> Text -> Text
+  query qe queryText =
+    case parseDatalog queryText of
+      Right (Query texts literals) -> "#NYI"
+      Right otherStatement -> throw $ NonQueryException queryText otherStatement
+      Left ex -> throw $ CannotParseStatementException queryText ex
+

haskell-experiments/src/Datalog/QueryEngine.hs

@@ -6,3 +6,11 @@
 {-# LANGUAGE BlockArguments #-}
 
 module Datalog.QueryEngine where
+import Datalog.DatalogDB
+import Data.Text
+
+class QueryEngine qe where
+  queryEngine :: (DatalogDB db) => db -> qe
+  query :: qe -> Text -> Text
+
+