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".
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