Constrained genericity: Difference between revisions
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Thundergnat (talk | contribs) m (→{{header|Perl 6}}: Fix broken example.) |
m (J: remove stale intro quip, simplify, and add some narrative description) |
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=={{header|J}}== |
=={{header|J}}== |
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Implementation: |
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J is not a statically typed language, |
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but I do not see why we should not implement this in J: |
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<lang j>coclass'Connoisseur' |
<lang j>coclass'Connoisseur' |
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isEdible=:3 :0 |
isEdible=:3 :0 |
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coclass'FoodBox' |
coclass'FoodBox' |
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create=:3 :0 |
create=:3 :0 |
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assert isEdible_Connoisseur_ type=:y |
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collection=: 0#y |
collection=: 0#y |
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) |
) |
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add=:3 :0"0 |
add=:3 :0"0 |
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'inedible' assert |
'inedible' assert isEdible_Connoisseur_ y |
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collection=: collection, y |
collection=: collection, y |
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EMPTY |
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)</lang> |
)</lang> |
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An edible type would be a class that has a verb with the name 'eat' |
An edible type would be a class that has a verb with the name 'eat' (the task "eatable" requirement is checked on an object or class reference using the static method <code>isEdible_Connoisseur_</code>). |
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We have also defined a 'FoodBox' container class which can only contain edible objects. (Our add method returns returns an empty result since its purpose is to add to the container, not to produce a result.) |
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For example: |
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<lang j>coclass'Apple' |
<lang j>coclass'Apple' |
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eat=:3 :0 |
eat=:3 :0 |
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And here is a quicky demo of the above: |
And here is a quicky demo of the above: |
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<lang j> |
<lang j> |
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lunch=: |
lunch=:'' conew 'FoodBox' |
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a1=: conew 'Apple' |
a1=: conew 'Apple' |
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a2=: conew 'Apple' |
a2=: conew 'Apple' |
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