Difference between revisions of "Algebraic datatype"
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BrettGiles (talk | contribs) (Changing to redirect - page was converted some time ago.) |
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| + | #redirect [[Algebraic data type]] |
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| − | An algebraic data type is a data type in wich we specify the shape of each element. |
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| − | == Example == |
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| − | This description of trees seems to be missing something: |
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| − | <haskell> |
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| − | data Tree a = Leaf a | Branch (Tree a) (Tree a) |
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| − | </haskell> |
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| − | How would this describe a tree like this: |
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| − | <code> |
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| − | 5 |
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| − | / \ |
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| − | 4 7 |
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| − | </code> |
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| − | ---- |
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| − | <haskell> |
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| − | Branch (Branch (Leaf 5) (Leaf 4)) (Leaf 7) |
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| − | </haskell> |
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| − | Similar to Lisp's <code>((5 4) 7)</code> (or maybe <code>((5 . 4) . 7)</code>). |
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| − | <haskell> |
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| − | data Tree a = Leaf | Branch (Tree a) a (Tree a) |
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| − | Branch (Branch Leaf 4 Leaf) 5 (Branch Leaf 7 Leaf) |
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| − | </haskell> |
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| − | Leaf can handle empty trees. |
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| − | ---- |
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| − | <haskell> |
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| − | data Tree a = Leaf a | Branch a (Tree a) (Tree a) |
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| − | </haskell> |
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| − | and |
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| − | <haskell> |
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| − | data Tree a = Leaf a | Branch a [Tree a] |
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| − | </haskell> |
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| − | handle internally-labelled binary, and rose trees. |
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| − | [[Category:Glossary]] |
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Revision as of 01:40, 5 June 2007
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