我正在通过一些ECLiPSe文件,发现:
`nonvar/1` : Fails if Term is not instantiated
我试图这样做:
1. Query: nonvar(X). Result: No (AS EXPECTED)
2. Query: X=5, nonvar(X). Result: Yes (AS EXPECTED)
3. Query: X=5, nonvar(f(X)). Result: Yes, X=5. (AS EXPECTED)
现在,这一令人怀疑的结果使我感到不解:
4. Query: nonvar(f(X)). Result: Yes, X=X.
查询1 233份。 对我来说,4项成果是令人不快的。 根据非第1/1号文件,如果论点是经口头修正的,则该论点可以是:ANY PROLOG TERM (so, f(X)是罚款),如果是没有。
在4起案件中,该事件不是立即发生的,而是应当为NO而不是YES(X=X)。 如果我的理解不正确,或者它是否是欧洲自由与民主运动赞成文件的问题,请予以纠正? 我正在使用最新版本。
感谢!
在您的询问中,f(X)>>>>>。 The non-instantiated variability X but it is not se an uninstantiated/2007/5.
SWI-Prolog 帮助或许比照nonvar的含义更为明确:
nonvar(Term): True ifTermcurrently is not a free variable.
您可核实某一术语是否包含有<代码>ground/1的自由变量:
?- X = 5, ground(f(X)).
X = 5.
?- ground(f(X)).
false.
I ve read about it in a book but it wasn t explained at all. I also never saw it in a program. Is part of Prolog syntax? What s it for? Do you use it?
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