On Sun, Mar 04, 2012 at 04:17:39PM +0100, Ralf Hemmecke wrote:
>> Example
>> -------
>> a Tree over a type T is either a Leaf or
>> a Node containing v: T, left branch Tree, and right branch Tree.
>>
>
> Does this help?
>
> https://github.com/hemmecke/fricas-svn/blob/master/src/algebra/tree.spad.pamphlet#L28
I try to follow this, only to have a simpler example.
Define a
binary tree with INT in its nodes:
-------------------------------------------------------
INT ==> Integer
)abbrev domain BTREE BTree
BTree() : Export == Implementation where
Export == SetCategory with
tree : INT -> %
sumTree : % -> INT
Implementation == add
Node := Record(val : INT, left : %, right : %)
Rep := Union(leaf : INT, node : Node)
tree(n : INT) : % == [n] :: Rep
sumTree tr ==
tr case leaf => tr.leaf
tr case node =>
nd := tr.node
nd.val + sumTree(nd.left) + sumTree(nd.right)
--------------------------------------------------
-> tree 0
Internal Error
The function coerce with signature hashcode is missing from domain
BTree
Please, how to correct this?
How to change the implementation tree(n)
so that it would build, for example,
n
/ \
n+1 n-1
:: BTree
?
Thanks,
------
Sergei
[email protected]
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