On Tue, 10 Jul 2007, Aaron Denney wrote: > On 2007-07-10, Dan Piponi <[EMAIL PROTECTED]> wrote: > > On 7/10/07, Andrew Coppin <[EMAIL PROTECTED]> wrote: > >> But what does, say, "Maybe x -> x" say? > > > > Maybe X is the same as "True or X", where True is the statement that > > is always true. Remember that the definition is > > > > data Maybe X = Nothing | Just X > > > > You can read | as 'or', 'Just' as nothing but a wrapper around an X > > and Nothing as an axiom. > > > > So Maybe X -> X says that "True or X" implies X. That's a valid proposition. > > It is? Doesn't look like it. Unless you just mean "grammatical" by > valid, rather than "true". >
It's true in Haskell - undefined is a valid proof of anything you like, which is of course rather unsound. -- [EMAIL PROTECTED] A problem that's all in your head is still a problem. Brain damage is but one form of mind damage. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
