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I have a list in Prolog like this: 

Puzzle = [ A1, A2, A3,
           B1, B2, B3,
           C1, C2, C3 ].

And I want every variable in the list to be a number in the range of 1 to 9. Currently I'm doing this like so:

between(1,9, A1),
between(1,9, A2),
% ...
between(1,9, C3).

Even though this works, it's already pretty ugly even for the only 9 numbers I have so far. However I will have to expand my list to contain at least 81 numbers at first (A1 till I9), and even 405 in the end.

I would rather not 'write' 405 lines of code just to limit the range of the numbers in the list, but since I'm new to Prolog, I don't know how I can improve this.

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Before moving on, I would strongly advise you to actually try to learn the language. What you are asking here is very basic and fundamental to using the language. –  Jeff Mercado Apr 26 '13 at 14:35

2 Answers 2

up vote 1 down vote accepted

Once you will have to hardcode your list to include all the variables from A1 to I9. Then you can iterate through it:

foreach(X, Your_list) do between(1, 9, X).
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up vote 0 down vote

In SWI-Prolog you can simply do:

?- numlist(1,9,Puzzle).
Puzzle = [1, 2, 3, 4, 5, 6, 7, 8, 9].
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