On Sat, 01 Dec 2007 21:22:53 -0600, Derek Elkins wrote:
Use ST. First-class state isn't too great unless you specifically want that.
I did try using ST but ran into a problem because its type variable (s) ended up invading all of my types. -- Target needs 's' because of the STRef data Target s = TValue Value | TVar (STRef s (Maybe Value)) -- Env needs 's' because Target needs 's' type Env s = Map Ident (Target s) -- Value needs 's' because closures are values and closures -- have an Env. data Value s = VUnit | VClosure (Env s) Ident Expr The main thing I didn't like was that 'Value' had a type parameter. I didn't follow the ST option much past this point. But maybe there's a better way to use ST? Will existential types help me? - Kannan