Talk:Tree from nesting levels: Difference between revisions
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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: |
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: |
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< |
<lang python>def levelList(x): |
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'''A Tree in which |
'''A Tree in which each node is a tuple of two values: |
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A possible integer, and a list of trees. |
A possible integer, and a list of trees. |
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(Int or None, [Tree]) |
(Int or None, [Tree]) |
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else: |
else: |
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return (x.get('Just', 0), concat(xs)) |
return (x.get('Just', 0), concat(xs)) |
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return go</ |
return go</lang> |
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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: |
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: |
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