definition module sem
from Data.Either import :: Either
-from AST import :: AST
-from lex import :: Error
+from AST import :: AST, :: Pos, :: Type
+from StdOverloaded import class toString
-semanticAnalysis :: AST -> Either String AST
+:: SemError
+ = ParseError Pos String
+ | UnifyError Pos Type Type
+ | UnifyErrorStub Type Type
+ | Error String
+:: SemOutput :== Either [SemError] AST
+
+
+instance toString SemError
+
+sem :: AST -> SemOutput