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@gmail.com On Sun, Feb 15, 2009 at 5:33 PM, Henning Thielemann < lemming@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?