[Haskell-cafe] Can't Haskell catch up with Clean's uniqueness typing?

haskell-cafe.mail.zooloo at xoxy.net haskell-cafe.mail.zooloo at xoxy.net
Thu Dec 8 07:08:35 EST 2005

----- Original Message -----
From: "Tomasz Zielonka - tomasz.zielonka at gmail.com"
Sent: Wednesday, December 07, 2005 8:53 PM

> >
> > Clean-like _explicit_ uniqueness typing is not what I'm asking for in Haskell.
> So you want implicit, automatically inferred uniqueness typing -
> something that would be even more fragile and sensitive then current
> Haskell's space problems arising from laziness? ;-)

Maybe it's just my lacking insight, but why should uniqueness inferring be all that fragile? A uniqueness checker can be
rather robust, as is demonstrated by the Clean one, so all we'd have to worry about is how to find a good set of
supposedly unique node candidates to suggest to the checker. (It certainly would not work well the dumb way, like, trying
every single combination out of n^2 possibilities, where n is the total node count.)

Whatever suggestion gets through the uniqueness checker, the resulting code can't be consuming more space, slower, or
otherwise worse than the one without reusing unique nodes, can it? On the other hand, performance gains thereby seem
likely to me.

> > It might be possible to get extremely fast code out of ghc, but as an
> > overall impression, it's not easy, whilst Clean sort of gives it for
> > granted (well, struggeling with wrongly assigned uniqueness attributes
> > aside).
> Well, C sort of gives it for granted too, because it is very difficult
> to write inefficient, simple, specification-like code. I want to be able
> to write simple and elegant code, even if it is inefficient!

errr..., could you give me some clue how you'd expect automatically uniqueness detection to deteriorate your coding style?
I, for one, don't define elegance in terms of not running too fast. ;)

I don't feel very comfortable either with the impact _explicit_ uniqueness attributing has on the ease of coding. Anyway,
I am not arguing pro Clean but pro compile time sharing analysis here.

To be honest, your reply feels like a counterpart to the likewise questionable monad avoidance in Clean.



p. s.: Anyone knows what makes your cited mail appear in the list archive as beeing sent from my address? The copy I got
to my mailbox is ok.

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