Talk:Tree from nesting levels: Difference between revisions
→a self-consistent representation of these forests as lists of tuples
Line 69:
[1, [2, [[4]]]] -> [[1, [2, [[4]]]]]</pre>
[[User:Hout|Hout]] ([[User talk:Hout|talk]]) 12:23, 4 February 2021 (UTC)
To put this in a Python notation, if we '''start''' with one of these forests ('''lists''' of trees), mapping over each of its members with a foldTree catamorphism, passing a function like this to it:
<pre>def levelList(x):
'''A Tree in which is node is a tuple of two values:
A possible integer, and a list of trees.
(Int or None, [Tree])
'''
def go(xs):
if x.get('Nothing', False):
return (None, concat(xs))
else:
return (x.get('Just', 0), concat(xs))
return go</pre>
We can obtain a self-consistent representation of these forests as lists of tuples, in which the first value is a kind of sum type (Int or None), and the second value is itself a (possibly empty) forest:
<lang python>[]
[(1, [2, [None, [4, []]]])]
[(None, [None, [3, []]]), (1, [None, [3, []]]), (1, [])]
[(1, [2, [3, []]]), (1, [])]
[(None, [None, [3, []], 2, []]), (1, [None, [3, []]])]
[(None, [None, [3, [], 3, [], 3, []]]), (1, []), (1, [None, [3, [], 3, [], 3, []]])]</lang>
[[User:Hout|Hout]] ([[User talk:Hout|talk]]) 14:00, 4 February 2021 (UTC)
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