Hello Taral, Sunday, September 10, 2006, 9:45:33 PM, you wrote:
data Expr t = If (Expr Bool) (Expr t) (Expr t) Expr Int = Lit Int Expr Bool | Eq t = Eq (Expr t) (Expr t)
I find this somewhat unreadable due to the implicit "t" parameter not showing up on the left-hand side...
if you mean last line, i tend to agree. i was just a little impulsive and don't mentioned that we define existential here :) it may look as Expr Bool = Eq (Expr t) (Expr t) | Eq t Brian Hulley developed here an idea about implicit "forall" declaration just before class restrictions involving this variable, so it will be equivalent to: Expr Bool = Eq (Expr t) (Expr t) | forall t . Eq t -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com