Re: [Haskell-cafe] Painting logs to get a coloured tree

10 Feb 2009

      Hi,

Am Montag, den 09.02.2009, 16:41 -0700 schrieb Luke Palmer:
...
2009/2/9 Joachim Breitner <mail@joachim-breitner.de>
        Now while this works, and while ST is still somewhat pure, I'm
        wondering
        if there is no better way of expressing "This piece of
        information came
        from the point in a data structure, so something else can be
        put here
        easily".
You might want to look into zippers:
http://haskell.org/haskellwiki/Zipper
I thought about Zippers, but I understand that they improve _navigating_
in a Tree-like structure, or to refrence _one_ position in a tree.

But if I would deconstruct my tree to the list of _all_ locations, with
...
type Loc a = (Tree a, Cxt a)
and then run my algorithm that returns [(Loc a, Info)], it’s still not
clear to me how I can combine all of these locations to get back my
original Tree, annotated with the Info returned.
Thanks nevertheless,
Joachim

-- 
Joachim "nomeata" Breitner
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