diff --git a/app/Main.hs b/app/Main.hs
index bd96b90..8c55433 100644
--- a/app/Main.hs
+++ b/app/Main.hs
@@ -19,6 +19,7 @@ import Model.Enum
 import Data.Either
 
 -- :set args resources/testAll.rosetta resources/Generated/testAll.hs
+-- :l resources/Generated/testAll.hs
 -- |Reads a rosetta string from the first input argument and writes a haskell output to the file given as a second argument
 main :: IO ()
 main = do
diff --git a/resources/testAll.rosetta b/resources/testAll.rosetta
index 8a04822..0172897 100644
--- a/resources/testAll.rosetta
+++ b/resources/testAll.rosetta
@@ -3,32 +3,32 @@ enum PeriodEnum: <"The enumerated values to specified the period, e.g. day, week
     M displayName "month" <"Month">
     Y displayName "year" <"Year">
 
-type Period extends Something: <"description">
+type Period extends TestType: <"description">
     periodMultiplier 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.">
     testMany TestType (0..*) <"Test many">
     testSome TestSomeType (1..*) <"Test some">
     testMaybeOne TestZeroOneType (0..1) <"Test zero or one">
 
 type TestType:
-    periodMultiplier int (1..1)
+    testType int (1..1)
 
 type TestSomeType: <"description">
-    periodMultiplier 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.">
+    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 extends Period:
-    periodMultiplier int (1..1)
+type TestZeroOneType:
+    testZeroOneType int (1..1)
 
 type ObservationPrimitive:
-    periodMultiplier int (1..1)
+    observationPrimitive int (1..1)
 
 func EquityPriceObservation: <"Function specification for the observation of an equity price, based on the attributes of the 'EquityValuation' class.">
    inputs:
       equity int (1..1)
-      valuationDate ObservationPrimitive (1..1)
+      valuationDate ObservationPrimitive (0..1)
       valuationTime int (0..1)
       timeType TestType (0..1)
       determinationMethod ObservationPrimitive (1..*)
    output:
       observation ObservationPrimitive (0..1)
 
-   assign-output: if equity exists then valuationDate
\ No newline at end of file
+   assign-output: if 2 = 3 then valuationDate
\ No newline at end of file
diff --git a/src/PrettyPrinter/Function.hs b/src/PrettyPrinter/Function.hs
index 4db4b7d..2779931 100644
--- a/src/PrettyPrinter/Function.hs
+++ b/src/PrettyPrinter/Function.hs
@@ -6,6 +6,7 @@ import Prettyprinter
 import Model.Function
 import PrettyPrinter.General
 import PrettyPrinter.Type
+import Model.Type
   
 -- show printStatementTree 
 
@@ -15,7 +16,7 @@ printFunction f = show $ vcat [printFunctionSignature f, printFunctionBody f]
 
 -- |Converts the body of a Function into a haskell valid Doc
 printFunctionBody :: Function -> Doc a
-printFunctionBody (MakeFunction name _ _ _ ex) = pretty name <+> "=" <+> printExpression ex
+printFunctionBody (MakeFunction name _ inp _ ex) = pretty name <+> printVariableNames inp <+> "=" <+> printExpression ex
 printExpression :: Expression -> Doc a
 printExpression (Variable s) = pretty s
 printExpression (Int s) = pretty s
@@ -26,11 +27,27 @@ printExpression (Parens ex) = "(" <> printExpression ex <> ")"
 printExpression (List ex) = list (map printExpression ex)
 printExpression (Function name ex) = pretty name <> tupled (map printExpression ex) 
 printExpression (PrefixExp name ex) = pretty name <+> printExpression ex
+printExpression (PostfixExp "exists" ex) = "isJust" <+> printExpression ex
+printExpression (PostfixExp "is absent" ex) = "isNothing" <+> printExpression ex
+printExpression (PostfixExp "single exists" ex) = "length" <+> printExpression ex <+> "==" <+> "1"
+printExpression (PostfixExp "multiple exists" ex) = "length" <+> printExpression ex <+> ">" <+> "1" 
+printExpression (PostfixExp "count" ex) = "length" <+> printExpression ex
 printExpression (PostfixExp name ex) = pretty name <+> printExpression ex
+-- Equality expressions
+printExpression (InfixExp "=" ex1 ex2) = printExpression ex1 <+> "==" <+> printExpression ex2
+printExpression (InfixExp "<>" ex1 ex2) = printExpression ex1 <+> "/=" <+> printExpression ex2
+printExpression (InfixExp "any =" ex1 ex2) = printExpression ex2 <+> "`elem`" <+> printExpression ex1
+printExpression (InfixExp "all <>" ex1 ex2) = printExpression ex2 <+> "`notElem`" <+> printExpression ex1
+printExpression (InfixExp "and" ex1 ex2) = printExpression ex1 <+> "&&" <+> printExpression ex2
+printExpression (InfixExp "or" ex1 ex2) = printExpression ex1 <+> "||" <+> printExpression ex2
 printExpression (InfixExp name ex1 ex2) = printExpression ex1 <+> pretty name <+> printExpression ex2
 printExpression (IfSimple cond ex) = "if" <+> printExpression cond <+> "then" <+> printExpression ex <+> "else" <+> "Nothing"
 printExpression (IfElse cond ex1 ex2) = "if" <+> printExpression cond <+> "then" <+> printExpression ex1 <+> "else" <+> printExpression ex2
 
+-- |Converts a list of type attributes to a Doc with a list of variable names
+printVariableNames :: [TypeAttribute] -> Doc a
+printVariableNames vars = foldl (<+>) emptyDoc (map (pretty . attributeName) vars)
+
 -- |Converts a function into a haskell valid Doc representing the signature of the function
 printFunctionSignature :: Function -> Doc a
 printFunctionSignature (MakeFunction name description inputs output _) =
diff --git a/src/Semantic/FunctionChecker.hs b/src/Semantic/FunctionChecker.hs
index adfb4b7..4830cc4 100644
--- a/src/Semantic/FunctionChecker.hs
+++ b/src/Semantic/FunctionChecker.hs
@@ -5,13 +5,14 @@ import Model.Type
 import Semantic.ExpressionChecker
 import Semantic.TypeChecker
 import Data.Either
+import Data.Char
 
 -- |Checks if all the inputs and the out of a function call have valid types, and then checks that the assign-output expression is valid
 checkFunction :: ([Type], [Symbol]) ->  Function -> Either [TypeCheckError] Function
 checkFunction (definedTypes, definedFunctions) (MakeFunction name desc inp out ex)
     | isRight checkedEx && isRight checkedOut && null (lefts checkedIn) = 
         case typeMatch (attributeType $ fromRightUnsafe checkedOut, Model.Type.cardinality out) (fromRightUnsafe checkedEx) of
-            Right _ -> Right $ MakeFunction name desc (rights checkedIn) (fromRightUnsafe checkedOut) ex
+            Right _ -> Right $ MakeFunction (toLower (head name) : tail name) desc (rights checkedIn) (fromRightUnsafe checkedOut) ex
             Left err -> Left [err] 
     | otherwise = Left $ lefts [checkedOut] ++ lefts checkedIn ++ lefts [checkedEx]
         where 
diff --git a/src/Semantic/TypeChecker.hs b/src/Semantic/TypeChecker.hs
index 9aff846..c8f7d46 100644
--- a/src/Semantic/TypeChecker.hs
+++ b/src/Semantic/TypeChecker.hs
@@ -18,12 +18,21 @@ data TypeCheckError =
 -- |Checks whether a data type is valid
 checkType :: [Type] -> Type -> Either [TypeCheckError] Type
 checkType definedTypes (MakeType name super desc attr)
-    | null (lefts checkedAttr) = Right $ MakeType name super desc (rights checkedAttr)
+    | null (lefts checkedAttr) = case checkSuper definedTypes super of
+        Right superChecked -> Right $ MakeType name superChecked desc (rights checkedAttr)
+        Left err -> Left [err]
     | otherwise = Left $ lefts checkedAttr  
-    where checkedAttr = checkAttributes definedTypes attr 
+    where checkedAttr = checkAttributes definedTypes attr
 checkType _ (BasicType b) = Right (BasicType b)
 
 
+checkSuper :: [Type] -> Maybe Type -> Either TypeCheckError (Maybe Type)
+checkSuper _ Nothing = Right Nothing
+checkSuper definedTypes (Just super) = 
+    case checkAttributeType definedTypes super of
+        Right sup -> Right (Just sup)
+        Left err -> Left err
+
 -- |Checks whether all the types of the attributes of a data type are already defined
 checkAttributes :: [Type] -> [TypeAttribute] -> [Either TypeCheckError TypeAttribute]
 checkAttributes _ [] = []