Mercurial > repos > other > SevenLanguagesInSevenWeeks
annotate 3-Prolog/day2-unification.pl @ 58:90c4b7f28690
Add initial Day 2 notes for Prolog
| author | IBBoard <dev@ibboard.co.uk> |
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| date | Tue, 26 Sep 2017 20:58:49 +0100 |
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| children |
| rev | line source |
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| 58 | 1 % Unification works both sides of the equals: |
| 2 % (A, 2, C) = (1, B, 3). | |
| 3 % We can't actually run this from a file, because Prolog. We get: | |
| 4 % | |
| 5 % native code procedure (=)/2 cannot be redefined (ignored) | |
| 6 % | |
| 7 % But we can run it from the REPL. | |
| 8 % | |
| 9 % Lists have heads and tails: | |
| 10 % | |
| 11 % [a, b, c] = [Head|Tail]. | |
| 12 % | |
| 13 % Underscore is the wildcard variable: | |
| 14 % | |
| 15 % [a, b, c] = [_|Tail]. | |
| 16 % | |
| 17 % Note: It's not magic "Head|Tail", it's "[X|Y]" notation |