Prolog - generating numbers fitting given range

Question

I\'d like to use predicates like:

range(X,0,5)
range(X,4,200)
range(X,-1000000,1000000)
dom_range(X,-1000000,1000000)

with meaning :

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Answer 1

range in Gnu-Prolog can be solved with finite domains

range(X,Low,High) :- fd_domain(X,Low,High).

I don't know if dom_range(X,L,H) :- fd_domain(X,L,H) .

P.S. When playing with finite domains, you might like to use fd_set_vector_max/1

Answer 2

Dave's answer is almost perfect: there is no check to see if low < high. I added a condition and now it works fine (otherwise it generates numbers from low to infinity):

range(Low, Low, High).
range(Out,Low,High) :- NewLow is Low+1, NewLow =< High, range(Out, NewLow, High).

Hope that helps!

Answer 3

SWI-Prolog has the predicate between/3. so you would call it like between(0,5,X) to get the results you showed above. This predicate looks like this is implemented in C though.

If we have to write it in pure prolog (and speed&space is not a factor), you could try this following.

range(Low, Low, High).
range(Out,Low,High) :- NewLow is Low+1, range(Out, NewLow, High).