type AST =
    | Program               of  Statement List

and Statement =
    | DataType
    | Definition            of  (Identifier List) * Expression
    | FunctionDefinition    of  FunctionName: Identifier *
                                Parameters: Identifier List *
                                FunctionBody: Expression

and Expression =
    | Tuple                 of  Expression List
    | IfStatement           of  Comparison: Expression *
                                Then: Expression *
                                Else: Expression
    | CompoundExpression    of  Statement List * Expression
    | FunctionCall          of  FunctionName: Identifier *
                                Parameters: Expression List
    | Arg                   of  Arg

and Arg =
    | BinaryArg             of  LHS: Expression *
                                RHS: Expression *
                                Op: BinaryOperation
    | UnaryArg              of  Expression * UnaryOperation
    | Identifier            of  Identifier
    | Literal               of  Literal

and BinaryOperation =
    | BinaryOperation

and UnaryOperation =
    | UnaryOperation

and Identifier =
    | Identifier            of  string

and Literal =
    | Integer               of  int
    | Float                 of  single
    | Boolean               of  bool