On 06-Jun-2000, Bjarke Dahl Ebert <[EMAIL PROTECTED]> wrote:
> Has anyone made a generalization of accumArray, which allows users to
> implement a pure function using imperative features?
Yes. See the documentation for the `ST' module in the Hugs/ghc extension
libraries. I enclose a brief extract.
| 3.16. ST
|
| This library provides support for strict state threads, as described
| in the PLDI '94 paper by John Launchbury and Simon Peyton Jones
| [LazyStateThreads]. In addition to the monad ST, it also provides
| mutable variables STRef and mutable arrays STArray.
...
| data ST s a -- abstract type
| runST :: forall a. (forall s. ST s a) -> a
...
| data STArray s ix elt -- mutable arrays in state thread s
| -- indexed by values of type ix
| -- containing values of type a.
| newSTArray :: Ix ix => (ix,ix) -> elt -> ST s (STArray s ix elt)
| boundsSTArray :: Ix ix => STArray s ix elt -> (ix, ix)
| readSTArray :: Ix ix => STArray s ix elt -> ix -> ST s elt
| writeSTArray :: Ix ix => STArray s ix elt -> ix -> elt -> ST s ()
| thawSTArray :: Ix ix => Array ix elt -> ST s (STArray s ix elt)
| freezeSTArray :: Ix ix => STArray s ix elt -> ST s (Array ix elt)
| unsafeFreezeSTArray :: Ix ix => STArray s ix elt -> ST s (Array ix elt)
--
Fergus Henderson <[EMAIL PROTECTED]> | "I have always known that the pursuit
WWW: <http://www.cs.mu.oz.au/~fjh> | of excellence is a lethal habit"
PGP: finger [EMAIL PROTECTED] | -- the last words of T. S. Garp.
