[Haskell-cafe] What's the deal with Clean?
Edsko de Vries
edskodevries at gmail.com
Wed Nov 4 12:08:23 EST 2009
I'm not sure I follow you? The compiler can't reorder the two updates
or do them in parallel (IO is not a commutative monad). You might tell
the compiler this explicitly, but then are you writing lower and lower
level code, further removed from the functional paradigm.
On 4 Nov 2009, at 15:27, David Leimbach wrote:
> On Wed, Nov 4, 2009 at 7:11 AM, Edsko de Vries
> <edskodevries at gmail.com> wrote:
> On 4 Nov 2009, at 13:36, Alberto G. Corona wrote:
> I know what uniqueness means. What I meant is that the context in
> which uniqueness is used, for imperative sequences:
> (y, s')= proc1 s x
> (z, s'')= proc2 s' y
> is essentially the same sequence as if we rewrite an state monad to
> make the state explicit. When the state is the "world" state, then
> it is similar to the IO monad.
> Yes, as long as there is a single thing that is being updated
> there's little difference between the state monad and a unique type.
> But uniqueness typing is more general. For instance, a function
> which updates two arrays
> f (arr1, arr2) = (update arr1 0 'x', update arr2 0 'y')
> is easily written in functional style in Clean, whereas in Haskell
> we need to sequentialize the two updates:
> f (arr1, arr2)
> = do writeArray arr1 0 'x'
> writeArray arr2 0 'y'
> Those sequential updates can be run concurrently on both, just with
> different syntax though right?
> You can find a more detailed comparison in my thesis (https://www.cs.tcd.ie/Edsko.de.Vries/pub/MakingUniquenessTypingLessUnique-screen.pdf
> , Section 2.8.7).
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