Ross, Thanks very much. I was going to use
coal :: Vector a -> [a] coal = coal_ (\() -> []) (\x -> [x]) but I prefer your definitions. Dominic. ----- Original Message ----- From: "Ross Paterson" <[EMAIL PROTECTED]> To: "Dominic Steinitz" <[EMAIL PROTECTED]> Cc: <[EMAIL PROTECTED]> Sent: Saturday, September 20, 2003 5:19 PM Subject: Re: Polymorphic Recursion / Rank-2 Confusion > On Sat, Sep 20, 2003 at 12:01:32PM +0100, Dominic Steinitz wrote: > > Can anyone tell me why the following doesn't work (and what I have to do to > > fix it)? I thought by specifying the type of coalw as rank-2 would allow it > > to be used both at a and (a,b). > > Change the signature to > > coal_ :: (v -> [a]) -> (w -> [a]) -> Vector_ v w -> [a] > > Then you can define > > type Vector = Vector_ () > > coal :: Vector a -> [a] > coal = coal_ (const []) (:[]) _______________________________________________ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
