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Jon Fairbairn | 1 Oct 2009 17:25
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Re: Proposal (Trac ticket #3524): Add mfilter to Control.Monad

Jon Fairbairn <jon.fairbairn <at> cl.cam.ac.uk> writes:

> Following on from the discussion of #3453, I propose the addition of
> mfilter to Control.Monad. It's just List.filter for any MonadPlus. 

[...]

> Time limit for discussion: 1 October.

That looks like nem. con. to me.  Please can someone commit it?

--

-- 
Jón Fairbairn                                 Jon.Fairbairn <at> cl.cam.ac.uk
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Spencer Janssen | 2 Oct 2009 04:36
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Re: darcs patch: haskell-x11: add and export the list of cursors

On Tue, Sep 15, 2009 at 09:15:45AM -0700, Don Stewart wrote:
> Applied:
> 
>     http://darcs.haskell.org/X11/
> 
> We can do a release if you do some testing :)

Builds for me, the new module seems to work correctly.  Let's get it released.

Cheers,
Spencer Janssen
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Don Stewart | 5 Oct 2009 02:31
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Hackage timeout

Hey all,

Hackage timed out for me today during an upload. Looks like the index
didn't regenerate. I imagine this gets fixed on the next succesful
upload.

-- Don
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Bas van Dijk | 5 Oct 2009 09:27
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Re: Add instance IsString ShowS where fromString = showString

On Sun, Sep 27, 2009 at 10:51 PM, Bas van Dijk <v.dijk.bas <at> gmail.com> wrote:
> Hello,
>
> It would be really nice to use OverloadedStrings when constructing a
> ShowS, for example in a definition of showsPrec in an instance for
> Show.
>
> The patch attached in the ticket[3544] adds the necessary instance to
> base/GHC/Show.lhs:
>
> instance IsString ShowS where
>    fromString = showString
>
> Note that this does require TypeSynonymInstances.
>
> Discussion period 2 weeks.
>
> regards,
>
> Bas
>
> [3544] http://hackage.haskell.org/trac/ghc/ticket/3544
>

Just a reminder for this proposal. One week has passed and one to go.

Any comments, +1 or -1?

regards,
(Continue reading)

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Nicolas Pouillard | 5 Oct 2009 11:23
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Re: Add instance IsString ShowS where fromString = showString

Excerpts from Bas van Dijk's message of Mon Oct 05 09:27:07 +0200 2009:
> On Sun, Sep 27, 2009 at 10:51 PM, Bas van Dijk <v.dijk.bas <at> gmail.com> wrote:
> > Hello,
> >
> > It would be really nice to use OverloadedStrings when constructing a
> > ShowS, for example in a definition of showsPrec in an instance for
> > Show.
> >
> > The patch attached in the ticket[3544] adds the necessary instance to
> > base/GHC/Show.lhs:
> >
> > instance IsString ShowS where
> >    fromString = showString
> >
> > Note that this does require TypeSynonymInstances.
> >
> > Discussion period 2 weeks.
> >
> > regards,
> >
> > Bas
> >
> > [3544] http://hackage.haskell.org/trac/ghc/ticket/3544
> >
> 
> Just a reminder for this proposal. One week has passed and one to go.
> 
> Any comments, +1 or -1?

+1
(Continue reading)

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Sittampalam, Ganesh | 5 Oct 2009 11:42

RE: Add instance IsString ShowS where fromString = showString

Bas van Dijk wrote:
> Hello,
> 
> It would be really nice to use OverloadedStrings when constructing a
> ShowS, for example in a definition of showsPrec in an instance for
> Show.  
> 
> The patch attached in the ticket[3544] adds the necessary instance to
> base/GHC/Show.lhs:
> 
> instance IsString ShowS where
>     fromString = showString
> 
> Note that this does require TypeSynonymInstances.

-1 : I don't think it's appropriate to use a type synonym instance in a
standard library.

A concrete example of the problems this would cause is that it would
interfere with any generic function instance for IsString, e.g.

instance IsString b => IsString (a -> b) where
    fromString = const . fromString

I am not suggesting that such an instance is generally useful, but
people who wanted to use it in their own private code would be
obstructed from doing so by an instance for (String -> String).

Cheers,
(Continue reading)

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Duncan Coutts | 5 Oct 2009 11:20

Re: Hackage timeout

On Sun, 2009-10-04 at 17:31 -0700, Don Stewart wrote:
> Hey all,
> 
> Hackage timed out for me today during an upload. Looks like the index
> didn't regenerate. I imagine this gets fixed on the next succesful
> upload.

Did the same for me yesterday.

Duncan
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Ross Paterson | 5 Oct 2009 13:32
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Re: Add instance IsString ShowS where fromString = showString

On Sun, Sep 27, 2009 at 10:51:04PM +0200, Bas van Dijk wrote:
> It would be really nice to use OverloadedStrings when constructing a
> ShowS, for example in a definition of showsPrec in an instance for
> Show.
> 
> The patch attached in the ticket[3544] adds the necessary instance to
> base/GHC/Show.lhs:
> 
> instance IsString ShowS where
>     fromString = showString
> 
> Note that this does require TypeSynonymInstances.

and also FlexibleInstances.  I think that's a problem, as Ganesh outlined.
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Duncan Coutts | 5 Oct 2009 12:47

RE: Add instance IsString ShowS where fromString = showString

On Mon, 2009-10-05 at 10:42 +0100, Sittampalam, Ganesh wrote:
> Bas van Dijk wrote:
> > Hello,
> > 
> > It would be really nice to use OverloadedStrings when constructing a
> > ShowS, for example in a definition of showsPrec in an instance for
> > Show.  
> > 
> > The patch attached in the ticket[3544] adds the necessary instance to
> > base/GHC/Show.lhs:
> > 
> > instance IsString ShowS where
> >     fromString = showString
> > 
> > Note that this does require TypeSynonymInstances.
> 
> -1 : I don't think it's appropriate to use a type synonym instance in a
> standard library.

Strictly speaking it's not the type synonym that is worrying, it's the
need for flexible instances which then leads on to needing overlapping
and incoherent instances.

http://www.haskell.org/ghc/docs/latest/html/users_guide/type-class-extensions.html#instance-rules

> A concrete example of the problems this would cause is that it would
> interfere with any generic function instance for IsString, e.g.
> 
> instance IsString b => IsString (a -> b) where
>     fromString = const . fromString
(Continue reading)

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Lennart Augustsson | 5 Oct 2009 14:17
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Re: Add instance IsString ShowS where fromString = showString

-1

What Ganesh said.

On Mon, Oct 5, 2009 at 1:32 PM, Ross Paterson <ross <at> soi.city.ac.uk> wrote:
> On Sun, Sep 27, 2009 at 10:51:04PM +0200, Bas van Dijk wrote:
>> It would be really nice to use OverloadedStrings when constructing a
>> ShowS, for example in a definition of showsPrec in an instance for
>> Show.
>>
>> The patch attached in the ticket[3544] adds the necessary instance to
>> base/GHC/Show.lhs:
>>
>> instance IsString ShowS where
>>     fromString = showString
>>
>> Note that this does require TypeSynonymInstances.
>
> and also FlexibleInstances.  I think that's a problem, as Ganesh outlined.
> _______________________________________________
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Gmane