Sarah Thompson <[EMAIL PROTECTED]> writes:
[...]
> work that well for circuits because, for anything other than trivially
> simple components, the connections between nodes need to be labelled.
it's been a while since i used it, but i thought erwig's graph library
had labels on edges. it's a real
> What is the best way to represent cyclic data structures in Haskell?
There used to be some work on direct cyclic representations at UCL:
Dynamic Cyclic Data Structures in Lazy Functional Languages
Chris Clack, Stuart Clayman, David Parrott
Department of Computer Science, University Colleg
Hi Sarah,
On Mon, 2003-07-07 at 16:04, Sarah Thompson wrote:
> What is the best way to represent cyclic data structures in Haskell?
>
> Lists are trivial. Trees are trivial. But what if the thing you're
> trying to represent is shaped like an electronic circuit, ...
> ...
> How do people typical
G'day all.
On Mon, Jul 07, 2003 at 04:37:46PM +0100, Sarah Thompson wrote:
> I'd considered something like embedding the type in the IO monad, with
> links between components implemented as IORefs, but I'd really prefer
> something cleaner (pure functional). If the code ends up horribly
> comp
G'day all.
On Mon, Jul 07, 2003 at 04:04:17PM +0100, Sarah Thompson wrote:
> > I would also need to implement efficient indexes into the data structure
> > -- flat searching will be too slow for non-trivial amounts of data. In
> > C++, I'd implement one or more external (probably STL-based) ind
G'day all.
As you note, some kind of indirection is what you want here.
On Mon, Jul 07, 2003 at 04:04:17PM +0100, Sarah Thompson wrote:
> I would also need to implement efficient indexes into the data structure
> -- flat searching will be too slow for non-trivial amounts of data. In
> C++, I'd
--- Sarah Thompson <[EMAIL PROTECTED]> wrote:
> What is the best way to represent cyclic data structures in Haskell?
You _might_ find some useful ideas in
Franklyn Turbak and J. B. Wells. Cycle Therapy: A Prescription for Fold and
Unfold on Regular Trees. Third International Conference on Princ
Lazy evaluation means that you can embed nodes directly in a cyclic
structure, even though that would appear to create an indefinite
regression. In order to detect cycles, one might add a node
identifier. Here's a simple example:
[[
-- spike-cyclicstructure.hs
data Node = Node { nodeid :: Str
From reading your message, it seems you want a graph library of sorts.
The important bit is 'of sorts', unfortunately! Most graph libraries
I've seen to date (although I must admit that they have been written in
C and C++, including one I perpetrated personally) don't really work
that well for
Why not just use a GUID to represent each node. Then a C pointer just
becomes a GUID in a tuple alongside the node. The C pointer approach is
just a method to have the memory system dole out GUIDs. And it can be
generalised. Then all the tuples could be inserted in a hash table on the
GUID compone
Hi Sarah,
Representing cyclic structures is indeed somewhat tricky in a pure
functional language. The obvious representation (representing the link
structure implicitly in an algebraic data type) doesn't work, because
you can't obvserve cycles.
I recommend checking out two pieces of work in t
>From reading your message, it seems you want a graph library of sorts.
I've used FGL extensively and found it to be very nice. It even
provides both a purely functional interface as well as an
imperative-esque interface. It also comes with a bunch of standard
algorithms built in, though I don't
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