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annotate 3-Prolog/day1-food.pl @ 52:cbaa3546f3f8

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Add extra thought on why you sometimes get "no" and sometimes "yes" after variable lists
author IBBoard <dev@ibboard.co.uk>
date Tue, 26 Sep 2017 19:42:02 +0100
parents 178b18b4f9ba
children
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1 % Define some foods and "flavours".
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2 % Note that this is Americanised, so some of these definitions are generous!
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3 food_type(velveeta, cheese).
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4 food_type(ritz, cracker).
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5 food_type(spam, meat).
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6 food_type(sausage, meat).
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7 food_type(jolt, soda).
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8 food_type(twinkie, dessert).
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9
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10 flavour(sweet, dessert).
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11 flavour(savoury, meat).
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12 flavour(savoury, cheese).
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IBBoard <dev@ibboard.co.uk>
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13 flavour(sweet, soda).
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14
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15 food_flavour(X, Y) :- food_type(X, Z), flavour(Y, Z).
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IBBoard <dev@ibboard.co.uk>
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16 % Note: flavour(sweet, What) will return 'yes' and a closed set of answers because it is just all of the facts
178b18b4f9ba Start experimenting with Prolog
IBBoard <dev@ibboard.co.uk>
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17 % but "food_flavour(What, meat)" will return answers and then say 'no', because it hasn't been given a flavour()
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18 % fact for "ritz"/"cracker".
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cbaa3546f3f8 Add extra thought on why you sometimes get "no" and sometimes "yes" after variable lists
IBBoard <dev@ibboard.co.uk>
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19 % This doesn't explain why "food(What, meat)" returns "no" after spam and sausage, though. Maybe because there's
cbaa3546f3f8 Add extra thought on why you sometimes get "no" and sometimes "yes" after variable lists
IBBoard <dev@ibboard.co.uk>
parents: 51
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20 % flavour(savoury, meat) so Prolog knows savoury is associated with meat but doesn't know whether it is in a food()
cbaa3546f3f8 Add extra thought on why you sometimes get "no" and sometimes "yes" after variable lists
IBBoard <dev@ibboard.co.uk>
parents: 51
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21 % fact without more processing?