(m:ms) <- get
case insertLookupWithKey (\k a1 a2 -> a1) i t m of
(Nothing,m') -> put (m':ms)
_ -> fail $ "Duplicate variable declaration: "++show i
(m:ms) <- get
case insertLookupWithKey (\k a1 a2 -> a1) i t m of
(Nothing,m') -> put (m':ms)
_ -> fail $ "Duplicate variable declaration: "++show i