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

[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 doesn't allow you to
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.

Thanks

Neil