[Haskell-cafe] Theoretical question: are side effects necessary?
jerzy.karczmarczuk at unicaen.fr
Sat Mar 17 03:44:16 CET 2012
> Other external state is harder to emulate. For example, communication
> over a network most definitely requires some concept of a 'computation
> with side effects' since the network's response could change from
> request to request.
> In GHC, even IO objects are pure, but they conceptually represent
> functions that modify the state of reality.
I believe I begin to become a sectarian, with some idées fixes not so
It is the third or the fourth time that somebody recently puts the
equivalence between the communication with the outer world, and "side
effects". I contest that very strongly, perhaps a TRUE guru might
What a computer and the program it runs do to its hard environment has
NOTHING to do with side-effects. Even a completely angelic, pure as a
Cherub (but real) program will consume some electricity. And so what?!
Of course, in classical physics the state of the world changes
constantly (in a quantum world it is extremely ambiguous...), but the
question of purity of a program - in my opinion - concerns the program,
and nothing else. The networking is not expected to break the
referential transparency, or does it?
More information about the Haskell-Cafe