Ruby: Racc を利用した Prolog ミニパーサ - Qiita

class Prolog::Parser rule response : | term term : pred | list | number | atom | var terms : term { result = [val[0]] } | terms ',' term { result << val[2] } pred : atom '(' terms ')' { result = { val[0] => val[2] } } list : '[' ']' { result = [] } | '[' terms ']' { result = val[1] } | string string : DQWORD { result = val[0][1..-2] } number : INTEGER { result = val[0].to_i } | FLOAT { result = va