举一个小例子,我想在列表中插入符号
domains
element = symbol
list = element*
position = integer
predicates
insert (element, position, list, list) %(input,input,input,output)
clauses
insert (E,_,[],[E]).
insert (E, 1,[H|T],[E|[H|T]]). %(I insert E on the "first" position)
% I get errors how E and T are not bound. I have no idea how to make them bound
insert (E,P,[H|T],[H1|T1]) :-
P > 1,
P1 = P - 1,
insert (E,P1,T,T1).
它不起作用......但我不知道为什么。嗯它有点工作。我希望它向我显示outputList = [NEW_LIST]
,而不是显示每个symbolName=_
然后outputList = [_,_,_,_]
。
答案 0 :(得分:0)
显然符号数据类型存在一些问题,如果我使用整数,它会自行修复。
此外,这是必要的:
domains
element = integer
list = element*
position = integer
predicates
insert (element, position, list, list) %(input,input,input,output)
clauses
insert (E,_,[],[E]).
insert (E, 1,[H|T],[E|[H|T]]).
insert (E,P,[H|T],[H|T1]) :- % has to be "H" (or anything else) in both
P > 1, % so prolog understands what we are trying to do
P1 = P - 1, % don't really understand why though
insert (E,P1,T,T1). % I might be wrong