grammar MiniLisp
  rule root
    (expression)
  end
  rule expression
    ((space_p) "(" (space_p) (body) ")")
  end
  rule space_p
    (space)0..1
  end
  rule body
    ((expression) / (identifier) / (float) / (integer) / (string))0..
  end
  rule space
    \s1..
  end
  rule identifier
    (([a-zA-Z=*] [a-zA-Z=*_]0..) (space_p))
  end
  rule float
    (((integer) (("." [0-9]1..) / ("e" [0-9]1..))) (space_p))
  end
  rule integer
    ((("+" / "-")0..1 [0-9]1..) (space_p))
  end
  rule string
    ("\"" (("\\" .) / (!"\"" .))0.. "\"" (space_p))
  end
end