[Haskell-cafe] Referential Transparency and Monads

[Jonathan Cast]

On Fri, 2009-04-10 at 07:29 +0400, Miguel Mitrofanov wrote:
> On 10 Apr 2009, at 06:30, Jonathan Cast wrote:
> >  do
> >     s <- readFile "/my_file"
> >     writeFile "/my_file" "Hello, world!\n"
> >     threadDelay 10000 -- If you don't like threadDelay, just  
> > substitute forcing
> >                       -- an expensive thunk here
> >     writeFile "/my_file" s
> >
> > As a function from initial state to final state, this program is just
> > the identity;
> 
> No, since world state includes the user state itself, not just files  
> contents.

My programs are passing me around inside a state token?

jcc