definition module sem
+import qualified Data.Map as Map
from Data.Either import :: Either
-from AST import :: AST
-from lex import :: Error
-from parse import :: ParserOutput
+from AST import :: AST, :: Pos, :: Type
+from StdOverloaded import class toString
-:: SemOutput :== Either Error AST
+:: SemError
+ = ParseError Pos String
+ | UnifyError Pos Type Type
+ | UnifyErrorStub Type Type
+ | Error String
+:: Gamma
+:: SemOutput :== Either [SemError] (AST, Gamma)
-sem :: ParserOutput -> SemOutput
+instance toString SemError
+instance toString Gamma
+
+sem :: AST -> SemOutput