On Mon, November 6, 2006 9:21 am, Ross Paterson wrote: > On Mon, Nov 06, 2006 at 01:53:52PM +0000, Malcolm Wallace wrote: >> So the doubly bizarre thing is that, actually, `seq` does not control >> the evaluation order (which is the only valid reason for wanting to use >> it in the first place), but nevertheless it undesirably changes the >> semantics of programs such that equational reasoning no longer holds. > > When I've used seq, it's to ensure that a function is strict in that > argument, and therefore has been evaluated before the function is called. > (If the language had unlifted types, I might have used those instead). > Beyond that, I don't care exactly when it was evaluated; it might be > long before, thanks to propagation of strictness information. > > seq has a clear denotational semantics. One can still do equational > reasoning with it, though there will be side conditions about whether > something is _|_ or not. The downside is that the eta rules get such > side conditions, and polymorphic seq greatly weakens parametricity. > > Apart from that, the only thing wrong with seq is its name.
What would be the correct way to get the effect that he expected from seq? > > _______________________________________________ > Glasgow-haskell-users mailing list > [email protected] > http://www.haskell.org/mailman/listinfo/glasgow-haskell-users > > -- Seth Kurtzberg [EMAIL PROTECTED] Software Engineer Specializing in Reliability and Security _______________________________________________ Glasgow-haskell-users mailing list [email protected] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
