我的问题与this question有关。
我希望将以下prolog代码嵌入python程序中:
myEquation(A, B, C):-
var(A),number(B),number(C) -> A is B+C;
var(B),number(A),number(C) -> B is A-C;
var(C),number(A),number(B) -> C is A-B;
A =:= B + C.
我安装了pyswip
软件包并尝试了以下代码:
from pyswip import Prolog
prolog = Prolog()
prolog.assertz("myEquation(A, B, C):- var(A),number(B),number(C) -> A is B+C; var(B),number(A),number(C) -> B is A-C; var(C),number(A),number(B) -> C is A-B; A =:= B + C.")
prolog.assertz("myEquation(3,1,C).")
但这给了我错误:
ERROR: Syntax error: Operator priority clash
ERROR: assertz((myEquation(A, B, C):- var(A),number(B),number(C) -> A is B+C; var(B),number(A),number(C) -> B is A-C; var(C),number(A),number(B) -> C is A-B; A
ERROR: ** here **
ERROR: =:= B + C.)).
Traceback (most recent call last):
File "prologpy.py", line 4, in <module>
prolog.assertz("myEquation(A, B, C):- var(A),number(B),number(C) -> A is B+C; var(B),number(A),number(C) -> B is A-C; var(C),number(A),number(B) -> C is A-B; A =:= B + C.")
File "/home/cardio/.local/lib/python3.5/site-packages/pyswip/prolog.py", line 140, in assertz
next(cls.query(assertion.join(["assertz((", "))."]), catcherrors=catcherrors))
File "/home/cardio/.local/lib/python3.5/site-packages/pyswip/prolog.py", line 127, in __call__
"Returned: '", str(term), "'."]))
pyswip.prolog.PrologError: Caused by: 'assertz((myEquation(A, B, C):- var(A),number(B),number(C) -> A is B+C; var(B),number(A),number(C) -> B is A-C; var(C),number(A),number(B) -> C is A-B; A =:= B + C.)).'. Returned: 'error(syntax_error(operator_clash), string(b'assertz((myEquation(A, B, C):- var(A),number(B),number(C) -> A is B+C; var(B),number(A),number(C) -> B is A-C; var(C),number(A),number(B) -> C is A-B; A =:= B + C.)). ', 152))'.
如何解决此问题。我也可以像listed here一样使用其他一些与序言相关的python软件包。
答案 0 :(得分:1)
谓词定义末尾的.
太多。摆脱它。
例如,这是正确的:
?- assertz((foo :- bar)).
但这是不正确的:
?- assertz((foo :- bar.)).
如果您阅读示例provided with pyswip,则应注意,上面的本地Prolog代码转换为:
from pyswip import Prolog
prolog = Prolog()
prolog.assertz("(foo :- bar)")
和不是,如您所写,
prolog.assertz("(foo :- bar.)")