moving Traversable and Foldable to Prelude (Was: Control.Monad proposal: Add whenJust)

[Andreas Abel]

Maybe instead of fiddling with the current Prelude (which might break 
backwards compatibility), we should design a new prelude which is not 
automatically loaded but contains roughly the current prelude (with the 
list functions generalized to collections) plus the "modern" type class 
stack: Functor, Applicative, Monad, Foldable, Traversable, Monoid etc.

I am willing to write

   {-# LANGUAGE NoImplicitPrelude #-}
   import Base

if I get a decent, "modern" standard set of functions that could be 
considered as the base vocabulary of modern Haskell programmers...

I just do not want to think about the democratic process involved in 
this design...

Cheers,
Andreas

On 20.05.13 9:35 AM, Henning Thielemann wrote:
>
> On Sun, 19 May 2013, Anthony Cowley wrote:
>
>> I think this issue may be too big to rely on mailing list +1s. Is
>> there any precedent for having a web-based
>> poll of some sort? We often get more engagement in debates on IRC and
>> /r/haskell than the mailing list, so
>> let's not let the choice of forum drive the result.
>
> I also consider the proposal to be a pretty big thing. I am not sure
> that all people who are affected are aware of this discussion,
> especially since it happens under the subject "add whenJust". Changing
> the Prelude was only done for 'catch' as far as I remember. Moving
> Traversable and Foldable to Prelude is for me a precedent. It has more
> implications: I think it must also go into the Haskell 201x
> specification. It would mean that Traversable and Foldable are
> immediately in scope in every module. And what is the long-term goal?
> Shall Prelude contain all classes, that generalize Prelude's types?
> Applicative? Category? Monoid? MonadPlus? Semigroup? If you think this
> out, you may want not to do the first step in this direction.
>
> The reason for the proposal is really only to save writing some "import"
> statements for people who prefer the unqualified import style, right? I
> still think it is much simpler to achieve this by putting more effort in
> alternative Prelude projects.
>
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-- 
Andreas Abel  <><      Du bist der geliebte Mensch.

Theoretical Computer Science, University of Munich
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andreas.abel at ifi.lmu.de
http://www2.tcs.ifi.lmu.de/~abel/