Re: [Haskell-cafe] "Tying the knot" with unknown keys

G'day all. Quoting David Ritchie MacIver :

I was playing with some code for compiling regular expressions to finite state machines and I ran into the following problem. I've solved it, but I'm not terribly happy with my solution and was wondering if someone could come up with a better one. :-)

Doing structural induction is quite viable, as you noted. However, there are advantages to implementing explicit indirection. The main one is memory usage. Explicit indirection is much less leak-prone, and you can easily share structures thanks to hash consing. At any rate, I'm extremely curious as to how your code compares with mine, performance-wise: http://www.ninebynine.org/Software/HaskellRDF/Dfa/Dfa.lhs Cheers, Andrew Bromage