Efficiency of list indices in definitions

[Tom Schrijvers]

> A large part of what I'm looking for at the moment is simply to find a
> fast and efficient way to express cyclic graphs in Haskell because in
> a present research project I need to manipulate machines with hundreds
> and thousands of states and my current, simple implementation simply
> won't do: my jobs balloon in size and die.  At the same time, code
> written and run in the early eighties outperforms mine!!  (Blushing
> with shame.)  Basically, I'm trying to find out whether Haskell is
> inherently that much slower or whether I am simply not yet quite
> competent enough to approach the problem correctly.

Have you looked at the Functional Graph Library by Martin Erwig?
http://www.cs.orst.edu/~erwig/fgl/haskell/

Tom