May 2013 - Libraries - Haskell.org

Re: 2014 Applicative => Monad proposal
by Stephen Tetley 23 May '13

23 May '13

(+1) I would like to see this proposal go forward. Though I've previously expressed a preference for Monad/Applicative changes being ratified as part of a language revision - I've changed my mind in the last few days. Thanks to both David in this thread and Simon Peyton-Jones in the "Making Decisions" thread for constructive proposals, that hopefully will both see fruition.

4 3

Re: foldable flexible bridges (putting foldable+traversable in prelude) Re: Burning bridges
by wren ng thornton 23 May '13

23 May '13

On 5/21/13 11:02 AM, Casey McCann wrote: > Being a beginner is by definition an ephemeral state; the entire > purpose of being a beginner is to eventually stop being one. Don't > design a language (or anything else) around the needs of beginners > unless you intend that only beginners will use it, in which case one > wonders why they're even bothering. There's definitely merit in targeting a language for learners (e.g., Helium for Haskell, or Logo for Lisp). Still, I don't see why the desire to teach newcomers is such an issue here. That is, if we keep the Prelude minimal (as I discussed in my other posts), then there's nothing keeping us from offering a PegagogicalHaskell module which offers monomorphized versions of functions and whatever else people think would be helpful. Beginners can import PegagogicalHaskell, whereas advanced users can import Data.Whatever or MyFavoritePrelude. What's the problem? The problem is trying to cram this all into the Prelude, where it doesn't belong. -- Live well, ~wren

1 0

Re: Apologies
by wren ng thornton 23 May '13

23 May '13

On 5/21/13 2:06 AM, Gabriel Gonzalez wrote: > APIs are like monad tutorials: it's better to teach people starting from > something simple and concrete than something abstract. If the Prelude > is not for teaching purposes, then what is? But the Prelude _isn't_ for teaching purposes. The Prelude is required because the definition of Haskell is circular. For example, in order to desugar do-notation, arithmetic sequences, etc (this syntax being part of the "language"), it is necessary to have particular type-classes/functions in scope (these functions being part of the "libraries"). The whole reason for the Prelude is as a means of resolving this circularity. It is just a happy side-effect that the Prelude offers some other functions which may be useful for teaching or for reducing imports. I'm all for helping learners, and I recognize that excessive polymorphism/abstraction can flummox them, but the Prelude is not the place for teaching (nor for importing the kitchen sink). Given the reason for the Prelude's existence, it should IMO be kept as minimal as possible. -- Live well, ~wren

1 0

Re: Burning bridges
by Merijn Verstraaten 22 May '13

22 May '13

+1 Generalize Prelude -1 Remove from Prelude -1 Add more monomorphic stuff -1 Do nothing On May 22, 2013, at 16:39 , libraries-request(a)haskell.org wrote: > > Date: Wed, 22 May 2013 10:23:21 -0400 > From: Edward Kmett <ekmett(a)gmail.com> > Subject: Re: Burning bridges > To: Tom Murphy <amindfv(a)gmail.com> > Cc: Ian Lynagh <ian(a)well-typed.com>, "libraries(a)haskell.org" > <libraries(a)haskell.org> > Message-ID: > <CAJumaK-veN80hcW1jV7Zfri-hzHt9iaDoPkU=Z+tVrJQfkT9pQ(a)mail.gmail.com> > Content-Type: text/plain; charset="utf-8" > > +1 Generalise Prelude.mapM etc > -1 Remove Prelude.mapM etc > -1 Add more monomorphic variants to Prelude (e.g. whenJust) > -1 Nothing > > > On Wed, May 22, 2013 at 9:24 AM, <amindfv(a)gmail.com> wrote: > >> >> >> El May 22, 2013, a las 8:12 AM, Ian Lynagh <ian(a)well-typed.com> escribi?: >> >>> On Wed, May 22, 2013 at 11:49:29AM +0800, John Lato wrote: >>>> >>>> I suggest that we start a poll for a single, concrete proposal. If the >>>> poll forum is by email or similar, I further suggest that replies be >>>> limited strictly to +1/-1. >>> >>> I think there are 4 things it has been suiggested that we might do: >>> * Generalise Prelude.mapM etc >> >> +1 >> >>> * Remove Prelude.mapM etc >> >> -1 >> >>> * Add more monomorphic variants to Prelude (e.g. whenJust) >> >> 0 >> >>> * Nothing >> >> -1 >> >> Tom >> >> _______________________________________________ >> Libraries mailing list >> Libraries(a)haskell.org >> http://www.haskell.org/mailman/listinfo/libraries

2 1

Re: Burning bridges
by Gabriel Gonzalez 22 May '13

22 May '13

Alright, you guys convinced me: +1 for generalization -1 for removal -1 for adding more monomorphic stuff to Prelude -1 for doing nothing

2 1

Votes for generalizing mapM &c.
by Casey McCann 22 May '13

22 May '13

On Wed, May 22, 2013 at 8:12 AM, Ian Lynagh <ian(a)well-typed.com> wrote: > On Wed, May 22, 2013 at 11:49:29AM +0800, John Lato wrote: >> >> I suggest that we start a poll for a single, concrete proposal. If the >> poll forum is by email or similar, I further suggest that replies be >> limited strictly to +1/-1. Here are the current totals by my count, ignoring any 0s: > * Generalise Prelude.mapM etc +13 / -0 > * Remove Prelude.mapM etc +1 / -11 > * Add more monomorphic variants to Prelude (e.g. whenJust) +0 / -12 > * Nothing +0 / -13 - C.

2 1

Re: Burning bridges
by Gershom B 22 May '13

22 May '13

+1 Generalize Prelude -1 Remove from Prelude -1 Add more monomorphic stuff -1 Do nothing

1 0

HP 2013.2 - RC3 installers for OS X
by Mark Lentczner 21 May '13

21 May '13

The Mac OS X RC3 installers are up: Haskell Platform 2013.2.0.0 32bit rc3.signed.pkg<http://www.ozonehouse.com/mark/platform/Haskell%20Platform%202013.2.0.0%203…> Haskell Platform 2013.2.0.0 64bit rc3.signed.pkg<http://www.ozonehouse.com/mark/platform/Haskell%20Platform%202013.2.0.0%206…> Only difference in these from RC2 is that the missing documentation for network, random, and primitive has been restored. These will be the final, barring any catastrophic issue. — Mark 15dd8762c9800308cb7cfdd16ea1a8e74988e06a Haskell Platform 2013.2.0.0 32bit rc3.signed.pkg 89e6fb747816af69acabc5c04cee103257855614 Haskell Platform 2013.2.0.0 64bit rc3.signed.pkg

1 0

Re: foldable flexible bridges (putting foldable+traversable in prelude) Re: Burning bridges
by Oren Ben-Kiki 21 May '13

21 May '13

On Tue, May 21, 2013 at 3:20 PM, Oliver Charles <ollie(a)ocharles.org.uk> wrote: > As a Haskell beginner I actually found in confusing that once I'd learnt > the prelude functions I had to learn more functions again to get to the > generalised functions. I would have rather been taught the general > functions in the specific frame of lists, and then show why the type > signature is more general than one for lists > > - ocharles > Hear hear! I am unclear why beginners can't be taught the same way as today, but only giving examples where the data types are normal lists, and then in a more advanced chapter saying "actually, mapM (or whatever) works on more data types...". That said, if 100% backward compatibility is an issue (isn't it always? :-), perhaps having a *standard* "no training wheels" prelude would solve the problem? Assuming it was trivial to switch to it in the cabal package file and not in the sources themselves. I know there is a whole bunch of prelude replacements, but that's the problem - there is a whole bunch of them. As SPJ pointed out, the "burning bridges" phrase was about switching to new libraries, not to a new language/compiler. Would it be a "flexible bridge" if there was an official community effort to create a standard prelude 2.0 file? Oren.

1 0

Apologies
by Gabriel Gonzalez 21 May '13

21 May '13

I want to apologize to wren (and everybody else). I was tired and overreacted when the discussion started veering into making more breaking changes. I don't mind the Foldable changes too much. My main concerns are: * loss of monomorphism makes teaching more difficult * They can be generalized in other useful ways However, I don't consider those concerns show-stoppers.

3 5