On 13 Jul 2010, at 10:11, Shlomi Vaknin wrote:
> Thank you all for replying!
>
> I am really beginning my baby steps in this fascinating language, and was
> just wondering if it was possible to naturally scan lists with arbitrary
> lists (aka trees :) ).
Trees aren't lists, Trees are trees... Here's how you create one*
data Tree a = Leaf
| Branch a [Tree a]
This roughly says, a tree can be made up of two possible things... First, it
could be a leaf, and secondly, it could be a branch with an element at it, and
a list of subtrees.
Some example trees using this data type:
1) Leaf
2) Branch 5 []
3) Branch 5 [Leaf]
4) Branch 5 [Branch 10 [], Branch 20 [], Leaf, Branch 50 [Branch 10 [], Leaf]]
When you have really strong typing, you also have very well specified types.
You don't just use a list as if it were a tree, you declare what a tree is.
Bob
* In this case an arbitrarily branching tree, we could ofc declare different
forms of tree here._______________________________________________
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