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Today's Topics:
1. Re: Config data (Rein Henrichs)
2. Re: Config data (Sumit Sahrawat, Maths & Computing, IIT (BHU))
----------------------------------------------------------------------
Message: 1
Date: Sat, 06 Jun 2015 20:14:50 +0000
From: Rein Henrichs <[email protected]>
To: [email protected], The Haskell-Beginners Mailing
List - Discussion of primarily beginner-level topics related to
Haskell <[email protected]>, mike h <[email protected]>
Subject: Re: [Haskell-beginners] Config data
Message-ID:
<CAJp6G8x3ty13u+0N9vR8bnZKs-7jM63+XtXyZ6FUY=x9qtz...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Can we please not suggest "not recommended" solutions (that most of us
probably wouldn't use) without at least providing a recommended alternative?
You can parse the config file into a record and then either pass it as an
argument wherever it is needed or use Reader (or ReaderT) to make it more
implicit.
On Sat, Jun 6, 2015 at 12:16 PM Sumit Sahrawat, Maths & Computing, IIT
(BHU) <[email protected]> wrote:
> Yeah, sorry I missed the last line on my first read.
>
> The link I gave you also explains how to achieve the same functionality as
> global variables without using them.
> The unsafePerformIO hack works, but for small modules it's much more
> helpful to do it safely.
>
> On 7 June 2015 at 00:37, mike h <[email protected]> wrote:
>
>> Global state is an option - thanks. Didn't think Haskell allowed this.
>>
>> Having three modules may be more logical but doesn't it just put the same
>> problem into the new module?
>>
>> Thanks
>>
>>
>>
>> On Saturday, 6 June 2015, 19:43, Mike Houghton <
>> [email protected]> wrote:
>>
>>
>> Hi,
>>
>> I?ve haskell files parser.hs and email.hs
>> email.hs is a module imported into parser and parser has the main.
>>
>> email has various passwords and server names needed to connect and send
>> email. I want to have those details in a config file and read it in at
>> start - using say config module. I?m ok with this part but the
>> practicality of doing it eludes me...
>>
>> It seems to me that email module can either get the config details itself
>> or be told them by parser. If email wants to get them how would it do this?
>> It does not have a main that gets run so can?t load a config file.(can it
>> ??)
>>
>> However parser can load the config in its main and then tell mail what
>> the values are but how would mail save them?
>>
>> Of course I could chanage the signatures of the email send/receive
>> functions in mail to take the connection details but that seems wrong.
>>
>> Thanks
>>
>> Mike
>>
>>
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>
>
> --
> Regards
>
> Sumit Sahrawat
> _______________________________________________
> Beginners mailing list
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>
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Message: 2
Date: Sun, 7 Jun 2015 01:52:14 +0530
From: "Sumit Sahrawat, Maths & Computing, IIT (BHU)"
<[email protected]>
To: Rein Henrichs <[email protected]>
Cc: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] Config data
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On 7 June 2015 at 01:44, Rein Henrichs <[email protected]> wrote:
> Can we please not suggest "not recommended" solutions (that most of us
> probably wouldn't use) without at least providing a recommended alternative?
>
I wholeheartedly agree. I mentioned that it is not recommended, and gave a
link where that point was stressed much better than I could hope to do.
A global variable turns out be the most accessible and easy solution, and
it provides a good playground to experiment with trying to replace them
with something else.
--
Regards
Sumit Sahrawat
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