(<!>) ::
       RTuple        -- ^ Input RTuple
    -> ColumnName    -- ^ ColumnName key
    -> RDataType     -- ^ Output value
(<!>) t c = -- flip getRTupColValue
       -- (HM.!)
       case rtupLookup c t of
            Just v -> v
            Nothing -> error $ "*** Error in function Data.RTable.(<!>): Column \"" ++ c ++ "\" does not exist! ***" 


-- | Returns the 1st parameter if this is not Null, otherwise it returns the 2nd. 
(<!>) ::
       RTuple        -- ^ Input RTuple
    -> ColumnName    -- ^ ColumnName key
    -> RDataType
(<!>) t c = -- flip getRTupColValue
       -- (HM.!)
       case rtupLookup c t of
            Just v -> v
            Nothing -> error $ "*** Error in function Data.RTable.(<!>): Column \"" ++ c ++ "\" does not exist! ***" 


-- | Returns the 1st parameter if this is not Null, otherwise it returns the 2nd. 
(<!>) t c = -- flip getRTupColValue
       -- (HM.!)
       case rtupLookup c t of
            Just v -> v
            Nothing -> error $ "*** Error in function Data.RTable.(<!>): Column \"" ++ c ++ "\" does not exist! ***" 


-- | Returns the 1st parameter if this is not Null, otherwise it returns the 2nd. 