Re: [Haskell-cafe] IO is not a monad (and seq, and in general _|_)

2007-01-23 Thread Brandon S. Allbery KF8NH
Can someone explain to me, given that (a) I'm not particularly expert at maths, (b) I'm not particularly expert at Haskell, and (c) I'm a bit fuzzybrained of late: Given that _|_ represents in some sense any computation not representable in and/or not consistent with Haskell, why/how is

Re: [Haskell-cafe] IO is not a monad (and seq, and in general _|_)

2007-01-23 Thread Robert Dockins
On Jan 23, 2007, at 2:09 PM, Brandon S. Allbery KF8NH wrote: Can someone explain to me, given that (a) I'm not particularly expert at maths, (b) I'm not particularly expert at Haskell, and (c) I'm a bit fuzzybrained of late: Given that _|_ represents in some sense any computation not

Re: [Haskell-cafe] IO is not a monad (and seq, and in general _|_)

2007-01-23 Thread Seth Gordon
Brandon S. Allbery KF8NH wrote: Can someone explain to me, given that (a) I'm not particularly expert at maths, (b) I'm not particularly expert at Haskell, and (c) I'm a bit fuzzybrained of late: Me too... Given that _|_ represents in some sense any computation not representable in

Re: [Haskell-cafe] IO is not a monad (and seq, and in general _|_)

2007-01-23 Thread Brandon S. Allbery KF8NH
On Jan 23, 2007, at 14:48 , Robert Dockins wrote: Its possible, however, that I don't understand your question. The formula (p^~p)-q (AKA, proof by contradiction) is valid most classical and constructive logics that I know of, so I'm not quite sure what you're getting at. I'm not

Re: [Haskell-cafe] IO is not a monad (and seq, and in general _|_)

2007-01-23 Thread Brandon S. Allbery KF8NH
On Jan 23, 2007, at 14:58 , Seth Gordon wrote: The only catch I see to that POV is that the way `seq` is defined, undefined `seq` 42 *must* return an error. If this were analogous to (p^~p)-q, then undefined `seq` 42 would be allowed to return any value whatsoever. That's not quite what

Re: [Haskell-cafe] IO is not a monad (and seq, and in general _|_)

2007-01-23 Thread Neil Mitchell
Hi That's not quite what I was trying to say. (p^~p)-q is equivalent to _|_ in the sense that once you derive/compute (respectively) it, the world in which it exists breaks. I think thats a bit overly harsh view of _|_ to take. The world does not break once you compute _|_ - a _|_ value

Re: [Haskell-cafe] IO is not a monad (and seq, and in general _|_)

2007-01-23 Thread Brandon S. Allbery KF8NH
On Jan 23, 2007, at 15:34 , Neil Mitchell wrote: prove/compute anything you couldn't before. While removing _|_ from the language does make some things nicer to reason about, there aren't many corners where _|_ really gets in the way that much - seq being one of those few corners. But that

Re: [Haskell-cafe] IO is not a monad (and seq, and in general _|_)

2007-01-23 Thread Neil Mitchell
Hi prove/compute anything you couldn't before. While removing _|_ from the language does make some things nicer to reason about, there aren't many corners where _|_ really gets in the way that much - seq being one of those few corners. But that is exactly the problem: `seq` forces _|_ to

Re: [Haskell-cafe] IO is not a monad (and seq, and in general _|_)

2007-01-23 Thread Greg Buchholz
Brandon S. Allbery KF8NH wrote: That's not quite what I was trying to say. (p^~p)-q is equivalent to _|_ in the sense that once you derive/compute (respectively) it, the world in which it exists breaks. (I don't think formal logic can have a Haskell-like _|_, but deriving (p^~p)-q is

Re: [Haskell-cafe] IO is not a monad (and seq, and in general _|_)

2007-01-23 Thread Brandon S. Allbery KF8NH
On Jan 23, 2007, at 15:50 , Neil Mitchell wrote: prove/compute anything you couldn't before. While removing _|_ from the language does make some things nicer to reason about, there aren't many corners where _|_ really gets in the way that much - seq being one of those few corners. But