Mercurial > repos > other > SevenLanguagesInSevenWeeks
comparison 3-Prolog/day1-wallaceandgrommit.pl @ 51:178b18b4f9ba
Start experimenting with Prolog
| author | IBBoard <dev@ibboard.co.uk> |
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| date | Mon, 25 Sep 2017 20:49:52 +0100 |
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| 50:b94161b72db6 | 51:178b18b4f9ba |
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| 1 % Start with some simple facts | |
| 2 % Note: like semantic systems, names are intrinsicly equal variables | |
| 3 % (or variables don't exist). Names are called "atoms" | |
| 4 likes(wallace, cheese). | |
| 5 likes(grommit, cheese). | |
| 6 likes(wendolene, sheep). | |
| 7 % Each statement ends with a fullstop | |
| 8 | |
| 9 % Rule syntax is a bit odd (":-" and "\+") but we're saying that X and Y | |
| 10 % can be friends if X and Y like the same thing. | |
| 11 % Poor Wendolene. | |
| 12 friend(X, Y) :- \+(X = Y), likes(X, Z), likes(Y, Z). | |
| 13 % "\+" is apparently logical negation (because of course it is) | |
| 14 % so the first "subgoal" stops Wallace being Wallace's friend | |
| 15 % | |
| 16 % Note: Prolog nomenclature is that this is "friend/2" - friend func with 2 params |