Quoth Jeff Shaw
I'm thinking that side effects are really only necessary because Haskell programs expect to mutate the state of a computer outside of the haskell program.
I'm not a computer scientist, but in English, "side effect" is an effect that accompanies some other effect. E.g., you may take an antihistamine to relieve hay fever, and experience a side effect of drowsiness. Let's call the first an `intended effect'? Then in the matter of the computer outside the Haskell program - which is intended effect, and which is side effect? I'd have said, side effects would be like memory paging, deferred resource access for other processes, etc.? Some programs might leave behind temporary files ... I hope the answer is not that in computer science we regard all effects as side effects because the ideal computer program simply exists without consequence. Donn