[Haskell-cafe] Identity of indiscernibles
jerzy.karczmarczuk at unicaen.fr
Thu Aug 8 15:38:41 CEST 2013
I am sorry for having mixed-up arguments (but who throws the first
> Jerzy seemed to suggest that the "impurity" of IO was somehow related to it
> not supporting very many operations.
No, not really. I added
> First, it is not true that you can do with, say, (printStr "Ho!" )
> whatever you want. In fact, you can do almost nothing with it. You can
> transport it "as such", and you can use it as the argument of (>>=).
after the message of Jake McA.
> /You can do whatever you want with them/ with no harmful effects in
> any Haskell expression.
This was an additional layer of bikeshedding, not exactly about purity.
Or, just a bit: the ONLY "real" operation on an action, i.e. (>>=)
produces side-effects... Other don't, but --
Again, here my point is that calling "pure" an entity which is opaque
and inert, is meaningless (or "redundant" if you wish...), this was all.
PS. Tom Ellis:
> One could simply implement IO as a free monad
Interesting. I wonder how.
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