Am Montag, 24. Januar 2005 22:59 schrieb Benjamin Franksen:
Both are wrong. 'just the result matters' is the correct POV for functions, but not for IO actions. 'everything matters' is wrong even for IO actions, because the actual value returned when the action is executed is completely irrelevant to the IO action's identity.
Now that I cannot swallow, that would mean return 4 == return 5. I suppose you didn't mean that, though. Maybe, the internal workings are irrelevant, only visible side-effects and the returned value? But which side-effects are relevant?
And also some of the electrons on transistor 19348587434 on the CPU chip move with a slightly reduced velocity due to the computer user shouting curses at his machine...
could that alter the number of reductions?
Seriously, the model in which the 'sameness' resp. identity of IO actions is defined takes into account only (a subset of all) externally observable effects, not the way a certain interpreter/compiler executes the action internally.
I'll stop here; think I have made my point
Yes, and I still don't know which effects do count and why these and not others.
Ben _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe