[Haskell-cafe] Re: Why purely in haskell?

Achim Schneider barsoap at web.de
Thu Jan 10 14:39:22 EST 2008

jerzy.karczmarczuk at info.unicaen.fr wrote:

> Achim Schneider: 
> > jerzy.karczmarczuk asks what's wrong with:
> >> > [1..] == [1..] 
> >> 
> >> Whatever you may say more, this is neither obscure nor a bug. I
> >> still wait for a relevant example. But I don't insist too much...  
> >> 
> > It's not an example of a bug, but of a cause.
> A cause of WHAT?? This is a perfect, nice, runaway computation, which
> agrees with all dogmas of my religion. 

The essence of laziness is to do the least work necessary to cause the
desired effect, which is to see that the set of natural numbers equals
the set of natural numbers, which, axiomatically, is always
computable in O(1) by equality by identity.

The essence of non-strictness, though, is another kind of story. Like
a golem plowing half of the country until you remember that you placed
him a bit absent-mindedly into your backyard and said "plow", that
still won't plow mountains.

The essence of strictness is easy, though: get stuck on a stone, fall
over and continue moving until you break.

And people just think axiomatically and then translate their
understanding more or less blindly into code, even if they can't name
the axiom(s).

Or, as I already mentioned:

| , for assumed operational semantics of ones own axiomatic semantics.
| Bugs are only a misunderstanding away.

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