[Haskell-cafe] do

[jerzy.karczmarczuk at info.unicaen.fr]

Peter Verswyvelen writes about non-monadic IO, unique "external worlds": 

> But... isn't this what the Haskell compiler & runtime do internally when 
> IO monads are executed? Passing the RealWorld "singleton" from "action" to 
> "action"? 

I never looked into any Haskell compiler. Chalmers, or York, don't remember,
used continuations, this seems a bit different from the Clean approach, but
I don't really know the gory details. 

> To me, no real 
> difference exists between IO monads and Clean's uniques types; it's just a 
> different approach to tackle the same problem. 

Yes, *different approach*. So, there *are* differences. Compilers, anyway,
are special applications. I wanted to see - responding to Brandon - a
"normal" Haskell program, which does IO without monads, that't all. 

The problem is then when you hide something, you hide. It is possible to
superpose a kind of monadic framework on unique worlds, files, etc. in
Clean, but the reverse operation goes beyond my horizons. 

Some examples, anybody? 

Jerzy Karczmarczuk