用 DCG 解析

DCG 可用于解析。最重要的是，相同的 DCG 通常可用于解析和生成正在描述的列表。例如：

sentence --> article, subject, verb, object.

article --> [the].

subject --> [woman] | [man].

verb --> [likes] | [enjoys].

object --> [apples] | [oranges].

示例查询：

?- phrase(sentence, Ls).
Ls = [the, woman, likes, apples] ;
Ls = [the, woman, likes, oranges] ;
Ls = [the, woman, enjoys, apples] .

?- phrase(sentence, [the,man,likes,apples]).
true .