diff --git a/src/Ast.hs b/src/Ast.hs
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+module Ast where
+
+type CompilationUnit = [Class]
+type DataType = String
+type Identifier = String
+
+data ParameterDeclaration = ParameterDeclaration DataType Identifier
+data VariableDeclaration = VariableDeclaration DataType Identifier (Maybe Expression)
+data Class = Class DataType [MethodDeclaration] [VariableDeclaration]
+data MethodDeclaration = MethodDeclaration DataType Identifier [ParameterDeclaration] Statement
+
+data Statement = If Expression Statement (Maybe Statement)
+               | LocalVariableDeclaration VariableDeclaration
+               | While Expression Statement
+               | Block [Statement]
+               | Return (Maybe Expression)
+               | StatementExpressionStatement StatementExpression
+
+data StatementExpression = Assignment Identifier Expression
+                         | ConstructorCall DataType [Expression]
+                         | MethodCall Identifier [Expression]
+
+data BinaryOperator = Addition
+                    | Subtraction
+                    | Multiplication
+                    | Division
+                    | BitwiseAnd
+                    | BitwiseOr
+                    | BitwiseXor
+                    | CompareLessThan
+                    | CompareLessOrEqual
+                    | CompareGreaterThan
+                    | CompareGreaterOrEqual
+                    | CompareEqual
+                    | CompareNotEqual
+                    | And
+                    | Or
+                    | NameResolution
+
+data UnaryOperator = Not
+                   | Minus
+
+data Expression = IntegerLiteral Int
+                | CharacterLiteral Char
+                | BooleanLiteral Bool
+                | NullLiteral
+                | Reference Identifier
+                | BinaryOperation BinaryOperator Expression Expression
+                | UnaryOperation UnaryOperator Expression
+                | StatementExpressionExpression StatementExpression
+                
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