[Haskell-cafe] On the purity of Haskell

[Conal Elliott]

On Fri, Dec 30, 2011 at 10:45 AM, Gregg Reynolds <dev at mobileink.com> wrote:

>
> On Dec 30, 2011, at 11:21 AM, Conal Elliott wrote:
>
> >
> > And I also raised a more fundamental question than whether this claim of
> sameness is true, namely what is equality on IO? Without a precise &
> consistent definition of equality, the claims like "f 42 == f (43 - 1)" are
> even defined, let alone true. And since the conversation is about Haskell
> IO, I'm looking for a definition that applies to all of IO, not just some
> relatively well-behaved subset like putchar/getchar+IORefs+threads.
>
> Well, you'll no doubt be glad to know I think I've said about all I need
> to say on this topic, [...]
>

Honestly, I'm not trying to get you to speak less, but rather to share your
perspective more clearly. I've have more than my fill of circular arguments
and ill-defined claims.

I'm reminded of a quote from David R. MacIver in “A problem of
language<http://www.drmaciver.com/2009/05/a-problem-of-language/>",


Of course, once you start defining the term people will start arguing about
> the definitions. This is pretty tedious, I know. But as tedious as arguing
> about definitions is, it can’t hold a candle to arguing without definitions.
>
- Conal
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