diff --git a/app/Main.hs b/app/Main.hs
index 8c55433..ecfae31 100644
--- a/app/Main.hs
+++ b/app/Main.hs
@@ -15,6 +15,7 @@ import Semantic.ExpressionChecker
 import Semantic.FunctionChecker
 import Model.Type
 import System.Environment.Blank (getArgs)
+import Parser.Expression
 import Model.Enum
 import Data.Either
 
diff --git a/resources/testAll.rosetta b/resources/testAll.rosetta
index 0172897..8966a13 100644
--- a/resources/testAll.rosetta
+++ b/resources/testAll.rosetta
@@ -15,7 +15,7 @@ type TestType:
 type TestSomeType: <"description">
     testSomeType int (1..1) <"A time period multiplier, e.g. 1, 2 or 3 etc. A negative value can be used when specifying an offset relative to another date, e.g. -2 days.">
 
-type TestZeroOneType:
+type TestZeroOneType extends Period:
     testZeroOneType int (1..1)
 
 type ObservationPrimitive:
@@ -27,8 +27,17 @@ func EquityPriceObservation: <"Function specification for the observation of an
       valuationDate ObservationPrimitive (0..1)
       valuationTime int (0..1)
       timeType TestType (0..1)
-      determinationMethod ObservationPrimitive (1..*)
+      determinationMethod ObservationPrimitive (1..1)
    output:
       observation ObservationPrimitive (0..1)
 
-   assign-output: if 2 = 3 then valuationDate
\ No newline at end of file
+   assign-output: if True and False then valuationDate
+
+func Something: <"asd">
+    inputs:
+        equity1 boolean (1..1)
+        something1 boolean (1..1)
+    output:
+        valuation ObservationPrimitive (1..1)
+
+    assign-output: if True and False then determinationMethod else determinationMethod
\ No newline at end of file
diff --git a/src/PrettyPrinter/Enum.hs b/src/PrettyPrinter/Enum.hs
index e14c6a9..988ffcb 100644
--- a/src/PrettyPrinter/Enum.hs
+++ b/src/PrettyPrinter/Enum.hs
@@ -13,7 +13,7 @@ printEnum (MakeEnum name description values) =
         (vcat ["data" <+> pretty name <+> "=", 
         indent 4 (printEnumValues values),
         "",
-        printDisplayNames name values])
+        printDisplayNames name values, emptyDoc])
     
 -- |Converts a list of EnumValues into a haskell valid Doc
 printEnumValues :: [EnumValue] -> Doc a
diff --git a/src/PrettyPrinter/Function.hs b/src/PrettyPrinter/Function.hs
index 2779931..ca0f469 100644
--- a/src/PrettyPrinter/Function.hs
+++ b/src/PrettyPrinter/Function.hs
@@ -12,7 +12,7 @@ import Model.Type
 
 -- |Converts a Function into a haskell valid String
 printFunction :: Function -> String
-printFunction f = show $ vcat [printFunctionSignature f, printFunctionBody f]
+printFunction f = show $ vcat [printFunctionSignature f, printFunctionBody f, emptyDoc]
 
 -- |Converts the body of a Function into a haskell valid Doc
 printFunctionBody :: Function -> Doc a
diff --git a/src/PrettyPrinter/Type.hs b/src/PrettyPrinter/Type.hs
index d10092a..545a182 100644
--- a/src/PrettyPrinter/Type.hs
+++ b/src/PrettyPrinter/Type.hs
@@ -8,15 +8,15 @@ import Model.Type
 
 -- |Converts an EnumType into a haskell valid String
 printType :: Type -> String
-printType (MakeType name (Just (MakeType super _ _ _)) description attributes) = printType (MakeType name Nothing description (superToAttribute super:attributes))
+printType (MakeType name (Just (MakeType super _ _ _)) description attributes) = printType (MakeType name Nothing description (superToAttribute name super:attributes))
 printType (MakeType _ (Just (BasicType _)) _ _) = error "Can't extend basic types"
 printType (MakeType name Nothing description attributes) =
-    show $ printDescription description (vcat [nest 4 $ vcat ("data" <+> pretty name <+> "=" <+> "Make" <> pretty name <+> "{": printAttributes attributes), "}", ""])
+    show $ printDescription description (vcat [nest 4 $ vcat ("data" <+> pretty name <+> "=" <+> "Make" <> pretty name <+> "{": printAttributes attributes), "}", "", emptyDoc])
 printType (BasicType name) = show $ pretty name
    
 -- |Creates an attribute that accesses the super type
-superToAttribute :: String -> TypeAttribute
-superToAttribute name = MakeTypeAttribute "super" (MakeType name Nothing Nothing []) (Bounds (1, 1)) (Just "Pointer to super class")  
+superToAttribute :: String -> String -> TypeAttribute
+superToAttribute name typ = MakeTypeAttribute ("super" ++ name) (MakeType typ Nothing Nothing []) (Bounds (1, 1)) (Just "Pointer to super class")  
    
 -- |Converts a list of TypeAttributes into a list of haskell valid Docs 
 printAttributes :: [TypeAttribute] -> [Doc a]
diff --git a/src/Semantic/ExpressionChecker.hs b/src/Semantic/ExpressionChecker.hs
index 360d786..4b222d7 100644
--- a/src/Semantic/ExpressionChecker.hs
+++ b/src/Semantic/ExpressionChecker.hs
@@ -100,8 +100,8 @@ checkExpression symbolMap (IfSimple cond ex)
         checkedExp = checkExpression symbolMap ex
 -- |Checks if the condition of the if statement is of type boolean, and then checks that both the then and else statements have the same type
 checkExpression symbolMap (IfElse cond ex1 ex2)
-    | isRight condType || isRight (typeMatch (fromRightUnsafe condType) (BasicType "Boolean", Bounds (1, 1))) = Left $ IfConditionNotBoolean $ show cond
-    | isRight ex1Type || isRight ex2Type || isRight (typeMatch (fromRightUnsafe ex1Type) (fromRightUnsafe ex2Type)) = Left $ IfExpressionsDifferentTypes (show ex1) (show ex2)
+    | isLeft condType || isLeft (typeMatch (fromRightUnsafe condType) (BasicType "Boolean", Bounds (1, 1))) = Left $ IfConditionNotBoolean $ show cond
+    | isLeft ex1Type || isLeft ex2Type || isLeft (typeMatch (fromRightUnsafe ex1Type) (fromRightUnsafe ex2Type)) = Left $ IfExpressionsDifferentTypes (show ex1) (show ex2)
     | otherwise = ex1Type
     where   condType = checkExpression symbolMap cond
             ex1Type = checkExpression symbolMap ex1
@@ -127,7 +127,7 @@ checkList1 symbs (ex : exps) typ
 
 -- |Checks whether the function that is called is already defined with the same argument types
 checkFunctionCall :: [Symbol] -> String -> [Either TypeCheckError (Type, Cardinality)] -> Either TypeCheckError (Type, Cardinality)
-checkFunctionCall [] fun args = Left $ UndefinedFunction $ "Undefined function: \"" ++ fun ++ "\" [" ++ concatMap (typeName . fst) (rights args) ++ "]"
+checkFunctionCall [] fun args = Left $ UndefinedFunction $ "Undefined function: \"" ++ fun ++ "\" [" ++ show (rights args) ++ "]"
 checkFunctionCall ((Func n a r):symbolMap) name args
     | length right /= length args = Left $ ErrorInsideFunction (name ++ ": " ++ show args ++ show (lefts args))
     | name == n && all isRight (zipWith typeMatch a right) = Right r