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Talk:Tree from nesting levels: Difference between revisions

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Talk:Tree from nesting levels (view source)

Revision as of 15:20, 8 February 2021

470 bytes removed ,  3 years ago
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→‎Simplified presentation of a consistent recursive data structure
Line 70:
[[User:Hout|Hout]] ([[User talk:Hout|talk]]) 12:23, 4 February 2021 (UTC)
 
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 – in Python terms (IntNone or Noneinteger), and the second value is itself a (possibly empty) forest:.▼
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:
 
<lang python># levelList :: Tree (Int|None)
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</lang>
 
▲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:
 
A consistent recursive data structure:
<pre>Node (None|Int) :: ((None|Int), [Node])</pre>
<lang python>(None, [])
(None, [(1, [(2, [(None, [(4, [])])])])])
Hout
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