Re: Default module header `module Main where`

2017-05-19 Thread Mario Blažević 

On 19/05/17 07:12 PM, Francesco Ariis wrote:

On Fri, May 19, 2017 at 06:32:30PM -0400, Joachim Breitner wrote:

I thought about this. But I fear that this will require a language
extension or flag, and then the developers (quite rightly) say that it
does not pull its weight of supporting both variants, and it gets lost.
But maybe I should give it a shot if they accept it.

Indeed this strikes me as a not a good extension to have: every extension
further fragments the ecosystem and is yet another thing to care about if
you are reading someone else's code, etc. - the cost probably outweights
the benefit on this one.

But it seems a good proposal for H2020, as (if it is accepted), the costs
linked with an extension/flag (added complexity, fragmentation of the
community) aren't there.

The "extensions before report modification" is a solid rule, maybe
the committee wants to add an exception for proposals which cannot
realistically be "packaged" (and achieve widespread use) into
extensions?


I feel it's rather ironic that there exists a class of proposals 
that are considered acceptable for Haskell' but too radical for GHC, 
considering that the stands are usually completely opposite.


The obvious way out of this conundrum is to communicate with GHC. 
If the Haskell' committee gives a proposal some sort of conditional 
acceptance status, that should count for something with the GHC HQ. 
After all, they'd presumably have to implement it once it's officially a 
part of the next standard, so implementing it sooner as a proposal is 
not that much more to ask.


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Re: Default module header `module Main where`

2017-05-19 Thread Francesco Ariis 
On Fri, May 19, 2017 at 06:32:30PM -0400, Joachim Breitner wrote:
> I thought about this. But I fear that this will require a language
> extension or flag, and then the developers (quite rightly) say that it
> does not pull its weight of supporting both variants, and it gets lost.
> But maybe I should give it a shot if they accept it.

Indeed this strikes me as a not a good extension to have: every extension
further fragments the ecosystem and is yet another thing to care about if
you are reading someone else's code, etc. - the cost probably outweights
the benefit on this one.

But it seems a good proposal for H2020, as (if it is accepted), the costs
linked with an extension/flag (added complexity, fragmentation of the
community) aren't there.

The "extensions before report modification" is a solid rule, maybe
the committee wants to add an exception for proposals which cannot
realistically be "packaged" (and achieve widespread use) into
extensions?
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Re: Default module header `module Main where`

2017-05-19 Thread Joachim Breitner 
Hi,

I thought about this. But I fear that this will require a language
extension or flag, and then the developers (quite rightly) say that it
does not pull its weight of supporting both variants, and it gets lost.
But maybe I should give it a shot if they accept it.

Joachim

Am Freitag, den 19.05.2017, 17:35 -0400 schrieb Mario Blažević:
> On 2017-05-16 10:18 AM, Joachim Breitner wrote:
> > Hi,
> > 
> > a very small proposal to be considered for Haskell':
> 
>   I like it, but it should probably be a GHC proposal first. I
> don't 
> think Haskell' is supposed to make any change to the standard that 
> hasn't been already implemented and tested. In this particular case,
> GHC 
> HQ might opt to implement your proposal but hide it behind a 
> command-line option, or to enable it by default only in GHCi. There
> are 
> already precedents for this.
> 
> 
> > 
> > Currently, the report states
> > 
> > An abbreviated form of module, consisting only of the module
> > body,
> > is permitted. If this is used, the header is assumed to be
> > ‘module
> > Main(main) where’.
> > 
> > I propose to change that to
> > 
> > An abbreviated form of module, consisting only of the module
> > body,
> > is permitted. If this is used, the header is assumed to be
> > ‘module
> > Main where’.
> > 
> > The rationale is that a main-less main module is still useful, e.g.
> > when you are working a lot in GHCi, and offload a few extensions to
> > a
> > separate file. Currently, tools like hdevtools will complain about
> > a
> > missing main function when editing such a file.
> > 
> > It would also work better with GHC’s -main-is flag, and avoid
> > problems
> > like the one described in https://ghc.haskell.org/trac/ghc/ticket/1
> > 3704
> > 
> > 
> > I don’t see any downsides. When compiling to a binary,
> > implementations
> > are still able to detect that a Main module is not imported by any
> > other module and only the main function is used, and optimize as if
> > only main were exported.
> > 
> > Greetings,
> > Joachim
> > 
> > 
> > 
> > 
> > 
> > ___
> > Haskell-prime mailing list
> > Haskell-prime@haskell.org
> > http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-prime
> > 
> 
> 
-- 
Joachim Breitner
  m...@joachim-breitner.de
  http://www.joachim-breitner.de/


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Re: Default module header `module Main where`

2017-05-19 Thread Carter Schonwald 
as a guideline what you say is true, and at least in this case as the
motivation is user focused it should be validated thusly :)

On Fri, May 19, 2017 at 5:35 PM, Mario Blažević  wrote:

> On 2017-05-16 10:18 AM, Joachim Breitner wrote:
>
>> Hi,
>>
>> a very small proposal to be considered for Haskell':
>>
>
> I like it, but it should probably be a GHC proposal first. I don't
> think Haskell' is supposed to make any change to the standard that hasn't
> been already implemented and tested. In this particular case, GHC HQ might
> opt to implement your proposal but hide it behind a command-line option, or
> to enable it by default only in GHCi. There are already precedents for this.
>
>
>
>> Currently, the report states
>>
>> An abbreviated form of module, consisting only of the module body,
>> is permitted. If this is used, the header is assumed to be ‘module
>> Main(main) where’.
>>
>> I propose to change that to
>>
>> An abbreviated form of module, consisting only of the module body,
>> is permitted. If this is used, the header is assumed to be ‘module
>> Main where’.
>>
>> The rationale is that a main-less main module is still useful, e.g.
>> when you are working a lot in GHCi, and offload a few extensions to a
>> separate file. Currently, tools like hdevtools will complain about a
>> missing main function when editing such a file.
>>
>> It would also work better with GHC’s -main-is flag, and avoid problems
>> like the one described in https://ghc.haskell.org/trac/ghc/ticket/13704
>>
>>
>> I don’t see any downsides. When compiling to a binary, implementations
>> are still able to detect that a Main module is not imported by any
>> other module and only the main function is used, and optimize as if
>> only main were exported.
>>
>> Greetings,
>> Joachim
>>
>>
>>
>>
>>
>> ___
>> Haskell-prime mailing list
>> Haskell-prime@haskell.org
>> http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-prime
>>
>>
>
> --
> Mario Blazevic
> mblaze...@stilo.com
> Stilo International
>
> This message, including any attachments, is for the sole use of the
> intended recipient(s) and may contain confidential and privileged
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> recipient(s) please contact the sender by reply email and destroy
> all copies of the original message and any attachments.
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Re: Default module header `module Main where`

2017-05-19 Thread Mario Blažević 

On 2017-05-16 10:18 AM, Joachim Breitner wrote:

Hi,

a very small proposal to be considered for Haskell':


	I like it, but it should probably be a GHC proposal first. I don't 
think Haskell' is supposed to make any change to the standard that 
hasn't been already implemented and tested. In this particular case, GHC 
HQ might opt to implement your proposal but hide it behind a 
command-line option, or to enable it by default only in GHCi. There are 
already precedents for this.





Currently, the report states

An abbreviated form of module, consisting only of the module body,
is permitted. If this is used, the header is assumed to be ‘module
Main(main) where’.

I propose to change that to

An abbreviated form of module, consisting only of the module body,
is permitted. If this is used, the header is assumed to be ‘module
Main where’.

The rationale is that a main-less main module is still useful, e.g.
when you are working a lot in GHCi, and offload a few extensions to a
separate file. Currently, tools like hdevtools will complain about a
missing main function when editing such a file.

It would also work better with GHC’s -main-is flag, and avoid problems
like the one described in https://ghc.haskell.org/trac/ghc/ticket/13704


I don’t see any downsides. When compiling to a binary, implementations
are still able to detect that a Main module is not imported by any
other module and only the main function is used, and optimize as if
only main were exported.

Greetings,
Joachim





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--
Mario Blazevic
mblaze...@stilo.com
Stilo International

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