[Haskell-cafe] ANNOUNCE: pqueue-mtl, stateful-mtl

Louis Wasserman wasserman.louis at gmail.com
Sun Feb 15 18:36:28 EST 2009

Well, it makes me sad, I guess.  pqueue-mtl provides an array-backed heap
monad transformer that is supposed to keep its own ST thread, if only for
the sake of retaining a purely functional interface without any externally
visible forall'd types, which is perfectly fine in most cases, but I'd have
to think about whether or not it'd remain referentially transparent if the
ST thread were only visible to a very tightly encapsulated set of commands
(i.e. priority queue operations).

Louis Wasserman
wasserman.louis at gmail.com

On Sun, Feb 15, 2009 at 5:33 PM, Henning Thielemann <
lemming at henning-thielemann.de> wrote:

> On Sun, 15 Feb 2009, Louis Wasserman wrote:
>  I follow.  The primary issue, I'm sort of wildly inferring, is that use of
>> STT -- despite being
>> pretty much a State monad on the inside -- allows access to things like
>> mutable references?
> I assume that ST must always be the most inner monad, like IO. Is this a
> problem in an application?
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