[Haskell-cafe] Are bottoms ever natural?

[Baa]

Also I want to point out to interesting and powerful language Shen:

     http://shenlanguage.org/learn-shen/index.html

which supports lazy evaluation, dependent types and many other things:
you can construct own rules in type-system level translator. I'm not
familiar with Shen but I suppose it's possible to programming without
"botton" in Shen. It supports Haskell too. By default partial functions
are "tracked" and can be traced, but w/ Dep. types this can be avoided
as I understand...

So, such languages exists ;)

===
Best regards, Paul

> Also, I'm sorry if the tone of the email is hostile, I don't mean it
> that way :) I just want to start a discussion about compiler and
> language design around lazy languages that permit bottom as an
> inhabitant.
> 
> On Tue 19 Dec, 2017, 08:20 (IIIT) Siddharth Bhat, <
> siddharth.bhat at research.iiit.ac.in> wrote:  
> 
> > Is that really true, though?
> > Usually when you have an infinite loop, you have progress of some
> > sort. Infinite loops with no side effects can be removed from the
> > program according to the C standard, for example. So, in general,
> > we should allow programmers to express termination / progress,
> > right? At that point, no computation ever "bottoms out"?
> >
> > Shouldn't a hypothetical purely functional programming language
> > better control this (by eg. Forcing totality?) It seems like we
> > lose much of the benefits of purity by muddying the waters with
> > divergence.
> >
> > From an optimising compiler perspective, Haskell is on some weird
> > lose-lose space, where you lose out on traditional compiler
> > techniques that work on strict code, but it also does not allow the
> > awesome stuff you could do with "pure" computation because bottom
> > lurks everywhere.
> >
> > What neat optimisations can be done on Haskell that can't be done
> > in a traditional imperative language? I genuinely want to know.
> >
> > What are your thoughts on this?
> >
> > Cheers
> >
> >
> > Siddharth
> >
> > On Tue 19 Dec, 2017, 08:09 Brandon Allbery, <allbery.b at gmail.com>
> > wrote: 
> >> Define "natural".
> >>
> >> You might want to look into the concept of Turing completeness.
> >> One could define a subset of Haskell in which bottoms cannot
> >> occur... but it turns out there's a lot of useful things you can't
> >> do in such a language. (In strict languages, these often are
> >> expressed as infinite loops of one kind or another. Note also that
> >> any dependency on external input is an infinite loop from the
> >> perspective of the language, since it can only be broken by the
> >> external entity providing the input.)
> >>
> >> On Tue, Dec 19, 2017 at 1:47 AM, (IIIT) Siddharth Bhat <  
> >> siddharth.bhat at research.iiit.ac.in> wrote:  
> >>  
> >>> I've been thinking about the issue of purity and speculation
> >>> lately, and from what little I have read, it looks like the
> >>> presence of bottom hiding inside a lazy value is a huge issue.
> >>>
> >>> How "natural" is it for bottoms to exist? If one were to change
> >>> Haskell and declare that any haskell value can be speculated
> >>> upon, what ramifications does this have?
> >>>
> >>> Is it totally broken? Is it "correct" but makes programming
> >>> unpleasant? What's the catch?
> >>>
> >>> Thanks,
> >>> Siddharth
> >>> --
> >>> Sending this from my phone, please excuse any typos!
> >>>
> >>> _______________________________________________
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> >>>  
> >>
> >>
> >>
> >> --
> >> brandon s allbery kf8nh                               sine nomine
> >> associates
> >> allbery.b at gmail.com
> >> ballbery at sinenomine.net
> >> unix, openafs, kerberos, infrastructure, xmonad
> >> http://sinenomine.net
> >> _______________________________________________
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> >
> > --
> > Sending this from my phone, please excuse any typos!
> >