Constrained genericity: Difference between revisions
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(→{{header|Scala}}: ++ sather, hopefully I've taken it right) |
(Added PicoLisp) |
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let your_box = FloatBox.make_box_from_list [2.3; 4.5]</lang> |
let your_box = FloatBox.make_box_from_list [2.3; 4.5]</lang> |
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Unfortunately, it is kind of cumbersome in that, for every type parameter we want to use for this generic type, we will have to explicitly create a module for the resulting type (i.e. <tt>BananaBox</tt>, <tt>FloatBox</tt>). And the operations on that resulting type (i.e. <tt>make_box_from_list</tt>) are tied to each specific module. |
Unfortunately, it is kind of cumbersome in that, for every type parameter we want to use for this generic type, we will have to explicitly create a module for the resulting type (i.e. <tt>BananaBox</tt>, <tt>FloatBox</tt>). And the operations on that resulting type (i.e. <tt>make_box_from_list</tt>) are tied to each specific module. |
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=={{header|PicoLisp}}== |
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<lang PicoLisp>(class +Eatable) |
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(dm eat> () |
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(prinl "I'm eatable") ) |
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(class +FoodBox) |
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# obj |
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(dm set> (Obj) |
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(unless (method 'eat> Obj) # Check if the object is eatable |
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(quit "Object is not eatable" Obj) ) |
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(=: obj Obj) ) # If so, set the object |
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(let (Box (new '(+FoodBox)) Eat (new '(+Eatable)) NoEat (new '(+Bla))) |
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(set> Box Eat) # Works |
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(set> Box NoEat) ) # Gives an error</lang> |
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Output: |
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<pre>$384320489 -- Object is not eatable |
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? (show Box) |
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$384320487 (+FoodBox) |
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obj $384320488 |
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? (show Box 'obj) |
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$384320488 (+Eatable) |
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? (show NoEat) |
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$384320489 (+Bla)</pre> |
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=={{header|Sather}}== |
=={{header|Sather}}== |
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