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Today's Topics:
1. Re: Foldable for (,) (Ryan Trinkle)
2. Cafe first, then beginners (Kim-Ee Yeoh)
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Message: 1
Date: Mon, 24 Apr 2017 22:48:01 -0400
From: Ryan Trinkle <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] Foldable for (,)
Message-ID:
<CAHNEpiz88b+gtauQYGOG=xfbdvpqgvrtsokdjpzs4jetzpj...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
I actually think the terminology may be the issue here: it's not tough to
think of cases where one might need to use (sum . fmap (const 1) ::
(Functor t, Foldable t) => t a -> Int), and it's also not tough to think of
cases where the term "length" doesn't fit everyone's expectation for what
that function does. On the other hand, there isn't really any other
Foldable-based implementation of 'length' that you can write.
On Mon, Apr 24, 2017 at 8:34 AM, <[email protected]> wrote:
>
>
> > El 24 abr 2017, a las 03:20, David Thomas <[email protected]>
> escribió:
> >
> > One thing that's been missed in this discussion is that constraints
> > can propagate.
> >
> > Of course no one is wanting to pass something they know is a tuple
> > into a function they know is length. But a function that expects
> > something Foldable might want to know length or sum, and it might be
> > reasonable to call that function on a tuple.
> >
>
> Do you have a real-world example of a case where that's useful, and
> difficult to achieve in another (non-Foldable) way?
>
> Genuinely asking, so that when we talk about what's gained/lost we have
> something concrete to talk about.
>
> Tom
>
>
>
> > On Sun, Apr 23, 2017 at 11:52 PM, Jonathon Delgado
> > <[email protected]> wrote:
> >> Tony Morris - please could you give a (practical) example of code where
> the a tuple could realistically be passed to length, but you don't know
> what the answer will be at compile time?
> >>
> >> Michael Orlitzky - everything in .NET has to descend from Object
> because of it's OO design. Why does tuple have to implement Foldable if it
> doesn't provide any useful functions?
> >>
> >> Thank you very much everyone in this thread for helping me understand!
> >> _______________________________________________
> >> Beginners mailing list
> >> [email protected]
> >> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
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Message: 2
Date: Tue, 25 Apr 2017 17:47:24 +0700
From: Kim-Ee Yeoh <[email protected]>
To: "[email protected]" <[email protected]>
Subject: [Haskell-beginners] Cafe first, then beginners
Message-ID:
<CAPY+ZdTWGiE+k6SXKn+9tdgB5Fg=w1-zfceo216zythojpu...@mail.gmail.com>
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Dear haskeller,
Please consider writing to the haskell-cafe mailing list with your
questions. Should you get an unsatisfactory response there, then retry your
queries here on haskell-beginners.
Here's why:
Haskell-cafe has about 10x the number of eyeballs.
Everyone here in haskell-beginners also reads haskell-cafe.
So you'll reach the same folks here but many, many more there.
This is especially helpful to you if your questions don't just deal with
LYAH-level language fundamentals but overlap specialized domains like
music, web dev, and infrastructure issues like OS, cabal, stack, etc.
Haskell-beginners started way back when there was much traffic coinciding
with an overflow of basic questions on cafe. Some folks, including
old-timers, felt overwhelmed. There was a sense that the latter convos
should be separated out.
But seasons change, and the cafe has dried up, mostly in volume but
thankfully not in subscriber count.
You will do your questions great justice if you air them in a forum capable
of rich and varied responses.
Best,
-- Kim-Ee
--
-- Kim-Ee
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