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Feature Request: Recursive Iterators (non-quadratic)

See original GitHub issue

Current if you want write a recursive based iterator function.

Iterator Function TreeWalk(Of T) ( curr As BinaryNode(Of T)) : IEnumerable(Of BinaryNode(Of T))
  If curr Is Nothing Then Return Enumerable.Empty(Of BinaryNode(Of T))
  ForEach node In TreeWalk( curr.Left )
    Yield node
  Next
  Yield curr
  ForEach node In TreeWalk( curr.Righ )
    Yield node
  Next
End Function

it ends up being Quadratic runtime

If I could express the Iterator / Yielder as a parameter I could linearise the runtime.

Iteration Function TreeWalk( n : BinaryNode, iterator As ?? ) : IEnumerable(Of T)
  If n Is Nothing Then Exit Functon
  If n.Left IsNot Nothing Then TreeWalk(n.Left, Iterator)
  Yield n.Value on Iterator
  If n.Righ IsNot Nothing Then TreeWalk(n.Righ, Iterator)
End Function

Issue Analytics

State:
Created 9 years ago
Reactions:7
Comments:26 (16 by maintainers)

Top GitHub Comments

1reaction

ufcppcommented, Jan 17, 2015

👍 I’d like this fearure to be added to C# too.

0reactions

gaftercommented, Mar 28, 2017

Issue moved to dotnet/csharplang #378 via ZenHub

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