可能的错误或遗漏

Question

可能的错误或者我遗漏了一些明显的东西：

 test(struct(X,Y)) --> X,[isa],Y.

当我尝试使用此规则时出现错误.. 前几天它还有效！！该列表在规则中使用了 phrase()，如果没记错的话应该是差异列表!!!

您的列表() 显示什么？

我错过了什么？看起来很愚蠢！唯一似乎合理的是我最近升级了 SWI ！！嗯..

Welcome to SWI-Prolog (threaded, 64 bits, version 8.2.3)
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For online help and background, visit https://www.swi-prolog.org
For built-in help, use ?- help(Topic). or ?- apropos(Word).

?- consult(test_grammar).
true.

?- listing(test).
test(struct(X, Y), A, B) :-
    phrase(X, A, C),
    C=[isa|D],
    phrase(Y, D, B).

true.

?- phrase(test(T), [this,isa,test]).
ERROR: Arguments are not sufficiently instantiated
ERROR: In:
ERROR:   [15] '$dcg':call_dcg(user:_9038,[this,isa|...],_9032)
ERROR:   [13] test(struct(_9082,_9084),[this,isa|...],[]) at /my/dev/python3/chatbot/lib/semantics/test_grammar.pl:2
ERROR:   [12] '$dcg':call_dcg(user:test(...),[this,isa|...],[]) at /usr/lib/swi-prolog/boot/dcg.pl:368
ERROR:    [9] <user>
ERROR: 
ERROR: Note: some frames are missing due to last-call optimization.
ERROR: Re-run your program in debug mode (:- debug.) to get more detail.
?-

Answer 1

你的语法规则应该是：

test(struct(X,Y)) --> [X,isa,Y].

这会给你：

?- [user].
|: test(struct(X,Y)) --> [X,isa,Y].
|: ^D% user://1 compiled 0.01 sec, 1 clauses
true.

?- phrase(test(T), [this,isa,test]).
T = struct(this, test).

可能的错误或遗漏

Possible bug or omission

prolog

dcg