src/Example.hs

@@ -107,6 +107,9 @@ exampleNullDeclaration = LocalVariableDeclaration (VariableDeclaration "Person"
 exampleNullDeclarationFail :: Statement
 exampleNullDeclarationFail = LocalVariableDeclaration (VariableDeclaration "int" "a" (Just NullLiteral))
 
+exampleNullAssignment :: Statement
+exampleNullAssignment = StatementExpressionStatement (Assignment (Reference "a") NullLiteral)
+
 testClasses :: [Class]
 testClasses = [
     Class "Person" [
@@ -246,3 +249,9 @@ runTypeCheck = do
         printResult "Result Null Declaration:" evaluatedNullDeclarationFail
         ) handleError
 
+    catch (do
+        print "====================================================================================="
+        evaluatedNullAssignment <- evaluate (typeCheckStatement exampleNullAssignment [("a", "Person")] sampleClasses)
+        printSuccess "Type checking of null assignment completed successfully"
+        printResult "Result Null Assignment:" evaluatedNullAssignment
+        ) handleError

src/Typecheck.hs

@@ -146,11 +146,11 @@ typeCheckStatementExpression (Assignment ref expr) symtab classes =
       ref' = typeCheckExpression ref symtab classes
       type' = getTypeFromExpr expr'
       type'' = getTypeFromExpr ref'
-    in
-      if type'' == type' then
-        TypedStatementExpression type' (Assignment ref' expr')
-      else
-        error $ "Type mismatch in assignment to variable: expected " ++ type'' ++ ", found " ++ type'
+  in
+    if type'' == type' || (type' == "null" && isObjectType type'') then
+      TypedStatementExpression type'' (Assignment ref' expr')
+    else
+      error $ "Type mismatch in assignment to variable: expected " ++ type'' ++ ", found " ++ type'
 
 typeCheckStatementExpression (ConstructorCall className args) symtab classes =
   case find (\(Class name _ _) -> name == className) classes of