grammar Expression
  include Keywords

  rule more_args
    list:(comma basic_expression )*
  end

  rule argument_list
    (left_parenthesis basic_expression? more_args? right_parenthesis){
        [ capture(:basic_expression).value ]
        }
  end

  rule call_site
    (basic_expression "." name_expression  argument_list space?) {
      Ast::CallSiteExpression.new(capture(:name_expression).to_str ,
                          capture(:argument_list).value ,
                          capture(:basic_expression).value )
    }
  end

  rule value_expression
    call_site | basic_expression
  end

  rule expression
#    (simple_return | while_do | conditional | operator_expression | call_site ) >> newline
    (call_site )  newline
  end

  rule function_definition
    keyword_def name:function_name  parameter_list  newline expressions_end  newline
  end

  rule parameter_list
    left_parenthesis parameter_list:( name:parameter?  (comma name:parameter)* ) right_parenthesis
  end

  root call_site
end