[Haskell-cafe] Re: Problem with own written monad

Achim Schneider barsoap at web.de
Mon Jan 7 14:08:24 EST 2008

Derek Elkins <derek.a.elkins at gmail.com> wrote:

> On Mon, 2008-01-07 at 18:21 +0000, Paul Johnson wrote:
> > Miguel Mitrofanov wrote:
> > >
> > > Yes. It's simply impossible. The Stack data type can't be turned
> > > into a monad.
> > Why not?  Surely this is just a variation on the theme of a state
> > monad?
> I somewhat explain in this reply:
> http://www.haskell.org/pipermail/haskell-cafe/2008-January/037605.html
Which states that the data structure doesn't support the Monad, or that
the Monad can't be implemented using that data structure.

So, see, some stack data type can certainly be turned into a monad, but
this Stack data type can't.

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