[Haskell-cafe] wondering about a MonadIO instance for a heap data type

[Qi Qi]

List [] is a monad, why not for heap data. Heap data could be an instance 
of Monad too. 
I have the heapsort function, and just wanted to rewrite a verbose version 
of it by using liftIO.
But I would look into Debug.Trace. Thanks for your hint.

Qi

On Wednesday, July 11, 2012 5:28:17 PM UTC-5, Eugene Kirpichov wrote:
>
> Use Debug.Trace.
> It does not make sense to declare that heap is a monad, as a monad is an 
> abstraction of sequencing computations, and a heap is not an abstraction of 
> sequencing computations at all. You don't make your String class implement 
> the "rendering engine" interface just because you want to use it in a 
> computer game program, equally you dont pretend that a heap is a way of 
> sequencing computations just because you want to sequence computations 
> related to heaps.
>
> The actual computation in your case is the heapsort function, not the 
> heap. If you absolutely must use IO, add IO to the functions type.
>
> 11.07.2012, в 15:19, Qi Qi <qiqi789 at gmail.com> написал(а):
>
> > Hi,
> > 
> > I was wondering about creating an instance of MonadIO for a heap data.
> > Any hints?
> > 
> > data Heap a = E | T Int a (Heap a) (Heap a)
> >     deriving (Eq, Ord, Read, Show)
> > 
> > The reason is that I want to use liftIO during a heapsort to print out
> > intermediate results.
> > 
> > Thanks.
> > 
> > Qi Qi
> > 
> > 
> > 
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