Brandon S. Allbery KF8NH wrote: > On May 8, 2009, at 01:33 , Joe Fredette wrote: >> That strikes me as being bad in a "I'm violating the Halting Problem" >> sort of way- but I'm not sure how. Is there some contradictory >> construction that could be built from such a function? > > I don't think it is; surely the Haskell runtime knows which thunks it > has evaluated. It just explicitly violates referential transparency, > and therefore must be in IO. You may be thinking that it would > return a result for _|_, but as described if you fed it _|_ it could > only produce False (if the _|_ has been evaluated you would not be > able to reach the test).
It could probably return True in GHC since you can catch exceptions. That still doesn't mean it solves the halting problem, of course. Ganesh =============================================================================== Please access the attached hyperlink for an important electronic communications disclaimer: http://www.credit-suisse.com/legal/en/disclaimer_email_ib.html =============================================================================== _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
