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Today's Topics:
1. what is a qualified type? (Christopher Howard)
2. Re: what is a qualified type? (Antoine Latter)
3. Re: what is a qualified type? (Kiki Sugiaman)
4. Re: what is a qualified type? (Christopher Howard)
5. Re: what is a qualified type? (Antoine Latter)
----------------------------------------------------------------------
Message: 1
Date: Thu, 09 Aug 2012 18:56:14 -0800
From: Christopher Howard <[email protected]>
Subject: [Haskell-beginners] what is a qualified type?
To: Haskell Beginners <[email protected]>
Message-ID: <[email protected]>
Content-Type: text/plain; charset="iso-8859-1"
In short, what is a qualified type and how is it used? (Any examples
would be appreciated.)
I feel somewhat embarrassed asking, as I used to know. I dropped Haskell
a while ago and am just now picking it up again, and unfortunately I
have forgotten many concepts.
If someone could point me to the appropriate tutorial that might be
enough. For some reason, all my StartPage searches are only bringing me
to documents that assume I already understand qualified types, or to
books I can't afford to buy.
--
frigidcode.com
indicium.us
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Message: 2
Date: Thu, 9 Aug 2012 21:54:11 -0500
From: Antoine Latter <[email protected]>
Subject: Re: [Haskell-beginners] what is a qualified type?
To: Christopher Howard <[email protected]>
Cc: Haskell Beginners <[email protected]>
Message-ID:
<cakjsnqgsqk_pjl5eqd8-n77_wk9n6+aatc+volbdnsn2+eu...@mail.gmail.com>
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On Thu, Aug 9, 2012 at 9:56 PM, Christopher Howard
<[email protected]> wrote:
> In short, what is a qualified type and how is it used? (Any examples
> would be appreciated.)
>
In what context are you seeing the term used?
Antoine
------------------------------
Message: 3
Date: Thu, 09 Aug 2012 22:26:24 -0500
From: Kiki Sugiaman <[email protected]>
Subject: Re: [Haskell-beginners] what is a qualified type?
To: [email protected]
Message-ID: <[email protected]>
Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
Are you talking about "import qualified" by any chance?
If so, this link explains the concept really well:
http://learnyouahaskell.com/modules
Good luck
On 08/09/2012 09:56 PM, Christopher Howard wrote:
> In short, what is a qualified type and how is it used? (Any examples
> would be appreciated.)
>
> I feel somewhat embarrassed asking, as I used to know. I dropped Haskell
> a while ago and am just now picking it up again, and unfortunately I
> have forgotten many concepts.
>
> If someone could point me to the appropriate tutorial that might be
> enough. For some reason, all my StartPage searches are only bringing me
> to documents that assume I already understand qualified types, or to
> books I can't afford to buy.
>
>
>
> _______________________________________________
> Beginners mailing list
> [email protected]
> http://www.haskell.org/mailman/listinfo/beginners
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Message: 4
Date: Thu, 09 Aug 2012 19:42:40 -0800
From: Christopher Howard <[email protected]>
Subject: Re: [Haskell-beginners] what is a qualified type?
To: Haskell Beginners <[email protected]>
Message-ID: <[email protected]>
Content-Type: text/plain; charset="utf-8"
On 08/09/2012 06:54 PM, Antoine Latter wrote:
> On Thu, Aug 9, 2012 at 9:56 PM, Christopher Howard
> <[email protected]> wrote:
>
> In what context are you seeing the term used?
>
> Antoine
>
I'm pulling the term vaguely from memory. The idea had something to do,
I think, with a type that has no other purpose than to qualify another
type, and somehow makes the programming more safe. I'm not referring to
qualified module imports, as someone suggested.
In my mind it is associated with "safe constructors" (another concept I
am relearning) but I'm not sure if the two concepts are actually related.
I know there is a book called "Qualified Types: Theory and Practice" by
Mark Jones <http://web.cecs.pdx.edu/~mpj/pubs/thesis.html> but I haven't
read it.
--
frigidcode.com
indicium.us
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Message: 5
Date: Thu, 9 Aug 2012 22:41:19 -0500
From: Antoine Latter <[email protected]>
Subject: Re: [Haskell-beginners] what is a qualified type?
To: Christopher Howard <[email protected]>
Cc: Haskell Beginners <[email protected]>
Message-ID:
<CAKjSnQEmyWRFFZSqvFEM64rGTn0zm0o3mcVawQySVp=y2u6...@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
On Thu, Aug 9, 2012 at 10:42 PM, Christopher Howard
<[email protected]> wrote:
> On 08/09/2012 06:54 PM, Antoine Latter wrote:
>> On Thu, Aug 9, 2012 at 9:56 PM, Christopher Howard
>> <[email protected]> wrote:
>>
>> In what context are you seeing the term used?
>>
>> Antoine
>>
>
> I'm pulling the term vaguely from memory. The idea had something to do,
> I think, with a type that has no other purpose than to qualify another
> type, and somehow makes the programming more safe. I'm not referring to
> qualified module imports, as someone suggested.
>
Perhaps you're thinking of phantom types? They can be used like that.
http://www.haskell.org/haskellwiki/Phantom_type
> In my mind it is associated with "safe constructors" (another concept I
> am relearning) but I'm not sure if the two concepts are actually related.
>
> I know there is a book called "Qualified Types: Theory and Practice" by
> Mark Jones <http://web.cecs.pdx.edu/~mpj/pubs/thesis.html> but I haven't
> read it.
>
> --
> frigidcode.com
> indicium.us
>
>
> _______________________________________________
> Beginners mailing list
> [email protected]
> http://www.haskell.org/mailman/listinfo/beginners
>
------------------------------
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