On 12/29/2011 07:07 PM, Steve Horne wrote:
On 29/12/2011 10:05, Jerzy Karczmarczuk wrote:
Sorry, a long and pseudo-philosophical treatise. Trash it before reading.
Heinrich Apfelmus:
You could say that side effects have been moved from functions to some other type (namely IO) in Haskell. I have no reason to be categorical, but I believe that calling the interaction of a Haskell programme with the World - a "side effect" is sinful, and it is a source of semantical trouble.
People do it, SPJ (cited by S. Horne) did it as well, and this is too bad. People, when you eat a sandwich: are you doing "side effects"?? If you break a tooth on it, this IS a side effect, but neither the eating nor digesting it, seems to be one.
By definition, an intentional effect is a side-effect. To me, it's by deceptive redefinition - and a lot of arguments rely on mixing definitions - but nonetheless the jargon meaning is correct within programming and has been for decades. It's not going to go away.
This doesn't sound right to me. To me, a "side effect" is something which happens as a (intended or unintended) consequence of something else. An effect which you want to happen (e.g. by calling a procedure, or letting the GHC runtime interpreting an IO Int) is just "an effect".