[Haskell-cafe] Modelling a mutable variable store

[Derek Elkins]

On Sun, 2007-12-02 at 03:29 +0000, Robin Green wrote:
> On Sat, 01 Dec 2007 21:22:53 -0600
> Derek Elkins <derek.a.elkins at gmail.com> wrote:
> 
> > > There's also the issue of finding a more elegant way of threading
> > > the Store through my evaluator, but I'm not concerned too much
> > > about that at this point.  I can probably define a state-carrying
> > > monad like Parsec. My real concerns are the first two issues.
> > 
> > Use ST.  First-class state isn't too great unless you specifically
> > want that.
> 
> Or use IO - that way you can use a Hashtable for looking up
> identifiers. Although, better still is to convert variable
> references into Ints, instead of using a Hashtable.

>From what I hear, Data.HashTable is impressively inefficient to the
extent that you're better off using Data.Map solely for performance (not
to mention it being pure.)