Improved error checking

Eval.hs

@@ -28,7 +28,7 @@ eval env expr = let (eval', evalFull') = (eval env, evalFull env) in case expr o
 
             IsEqual -> case args' of -- TODO not sufficent.
                 [e1, e2] -> Boolean (e1 == e2)
-                _ -> "isEqual argument error"
+                _ -> error "isEqual argument error"
             
             XProduct -> case inputSets' of
                 [(Set l1), (Set l2)] -> Set $ [ x `concatRecord` y | x <- l1, y <- l2]
@@ -38,16 +38,19 @@ eval env expr = let (eval', evalFull') = (eval env, evalFull env) in case expr o
                 [Boolean e1, Boolean e2] -> Boolean (e1 `op` e2)
                 _ -> error "Boolean function takes in two arguments."
 
-            RecordIndex -> eval' $ let (Record recordData:Int index:_) = args' in
-                recordData !! (index - 1)
+            RecordIndex -> eval' $ case args' of 
+                [Record recordData,Int index] -> recordData `listAtIndex` index
 --TODO CBH
             RecordSelect -> case args' of
                 (Record recordData: indexes ) -> Record filteredList
                     where
                         indexesRaw = map checkInt indexes
-                        filteredList = map (eval'.(recordData!!)) indexesRaw
-                        checkInt (Int i) = i - 1
+                        --filteredList = map (eval'.(recordData !!)) indexesRaw
+                        filteredList = map (eval'.listAtIndex recordData) indexesRaw
+                        checkInt (Int i) = i
                         checkInt _ = error "Arguments to index record must be integers"
+                        
+
                         {-numberedElems = zip [1..] recordData :: [(Int, Expr)]
                         filtered = filter ((`elem` indexesRaw).fst) numberedElems :: [(Int, Expr)]
                         filteredList = map snd filtered :: [Expr]-}
@@ -93,9 +96,13 @@ eval env expr = let (eval', evalFull') = (eval env, evalFull env) in case expr o
         let (newEnv, newControl) =  evalControl1 env control in
             eval newEnv newControl
 
+    (Record exprs) -> Record $ map eval' exprs
     (Record exprs) -> Record $ map eval' exprs
     _ -> expr
 
+listAtIndex :: [a] -> Int -> a
+listAtIndex recordData i | i > length recordData = error $ "Index " ++ show i ++ " too large."
+    | otherwise = recordData !! (i - 1)
 
 evalControl1 :: Environment -> Expr -> (Environment, Expr)
 evalControl1 env (Control last (currentExpr:exprs)) = (newEnv, Control newLast exprs)

Interpreter.hs

@@ -7,18 +7,24 @@ import CSV
 import Lexer
 import Parser
 import Debug.Trace
+import Control.Exception
+
+printErr s = hPutStrLn stderr ("[ERROR] " ++ s)
 
 parse :: String -> Program
-parse = parseSource.(\x -> let o = alexScanTokens x in traceShowId o)
+parse = parseSource.alexScanTokens
 --outline
 
 main = do
     args <- getArgs
     case args of
-        (srcname:_) -> interpret srcname
-        _ -> interpret "solutions/pr4.cql"
-        --_ -> interpret "extra-problems/pr3.cql"
-        --_ -> interpret "sampleprogram.txt"
+        --("default":_) -> catch (interpret "/home/patryk/dev/plc/extra-problems/ex1.cql") (errorFunc)
+        (srcname:_) -> catch (interpret srcname) (errorFunc)
+        --_ -> printErr "No source file specified."
+        _ -> catch (interpret "/home/patryk/dev/plc/extra-problems/ex1.cql") (errorFunc)
+
+errorFunc :: ErrorCall -> IO ()
+errorFunc = printErr.show
     
 
 interpret :: FilePath -> IO () -- the main function, takes in file name, prints out result