# Empty or Tree?

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## Empty or Tree?

 Hello everyone. I'm trying to write a code which works on binary trees. When I write code like this ?with a tree with empty nodes : data Tree ?= ?Empty | Node ?Integer Tree Tree function Node a (Node b Empty Empty)??(Node c Empty Empty) it works fine.? But when I try to create a more generic code like this ?which could ?work with trees who don't have empty nodes in grandchild level :? function Node a (Node b Tree Tree)??(Node c Tree Tree )? I get this error :?Undefined data constructor "Tree" Can you help me with creating more generic code please? Thanks -------------- next part -------------- An HTML attachment was scrubbed... URL:
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## Empty or Tree?

 I think this is because "Tree" is a data type and not a data constructor. According to your definition of Tree, Empty and Node are the constructors. Node a (Node b (Node c Empty Empty) (Node d Empty Empty)) (Node e (Node f Empty Empty) (Node g Empty Empty)) is a valid tree if a, b, c, d, e, f, g are integers. Hope this helps. -- Aditya. On 10 March 2012 15:58, bahad?r altan wrote: > Hello everyone. I'm trying to write a code which works on binary trees. > When I write code like this  with a tree with empty nodes : > > data Tree  =  Empty | Node  Integer Tree Tree > > function Node a (Node b Empty Empty)  (Node c Empty Empty) > > it works fine. > But when I try to create a more generic code like this  which could  work > with trees who don't have empty nodes in grandchild level : > > function Node a (Node b Tree Tree)  (Node c Tree Tree ) > > I get this error : Undefined data constructor "Tree" > > Can you help me with creating more generic code please? > Thanks > > > _______________________________________________ > Beginners mailing list > Beginners at haskell.org > http://www.haskell.org/mailman/listinfo/beginners> > -------------- next part -------------- An HTML attachment was scrubbed... URL:
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