How to expand a query into a list?
f(a,b).
f(a,c).
d(a.d).
expand(f(a,X), Out) -----> Out=[b,c,d]
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Use bagof/3 or setof/3. E.g.:
?- bagof(X, (X = 1; X = 2), L).
L = [1,2]
yes
In your case that would be
?- bagof(X, f(a,X), Out).
starblue
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How can I pass the output of bagof into length? length(bagof(),O). – TheOne Sep 18 '09 at 16:31
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3bagof(X, ..., L), length(L, N). You need to read some introduction to Prolog. – starblue Sep 18 '09 at 18:18