---------- Forwarded message ---------- From: Alberto G. Corona Date: 2009/12/15 Subject: Re: [Haskell-cafe] Boxed Mutable Arrays To: Daniel Peebles Ok, so the state content is not accessible. Nice. 2009/12/15 Daniel Peebles No, they are actually being mutated. ST is basically IO with a

universal state thread (IO uses RealWorld) to prevent you from letting any of the mutable structures out (or any in) of the block. The whole point of ST is to have real mutable references/arrays that have a referentially transparent if you look at them from outside.

Dan

On Tue, Dec 15, 2009 at 9:23 AM, Alberto G. Corona wrote:

...

AFAIK, ST Arrays are pure data structures. They are not really mutable. They are destroyed and recreated on every update. The mutation is just simulated thanks to the hidden state in the state monad. Sure, the garbage

collector > must have a hard work in recycling all the "backbones" of the discarded > arrays (not the elements). > > 2009/12/14 Brad Larsen <brad.larsen@gmail.com> >> >> Is anyone working on fixing ticket #650 >> <http://hackage.haskell.org/trac/ghc/ticket/650>? In short, STArray >> and the garbage collector don't play well together, resulting in array >> updates being non-constant time operations. This bug makes it very >> difficult/impossible to write efficient array algorithms that depend >> upon mutation in Haskell. >> >> On another note, does this (or perhaps better phrased, will this) bug >> also affect Data Parallel Haskell? >> >> I would really like to see highly efficient, mutable, boxed arrays in >> Haskell! Unfortunately, I don't have the know-how to fix Ticket 650. >> >> Sincerely, >> Brad >> _______________________________________________ >> Haskell-Cafe mailing list >> Haskell-Cafe@haskell.org >> http://www.haskell.org/mailman/listinfo/haskell-cafe > > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > >