[Haskell-beginners] what is a qualified type?

[Antoine Latter]

On Thu, Aug 9, 2012 at 10:42 PM, Christopher Howard
<christopher.howard at frigidcode.com> wrote:
> On 08/09/2012 06:54 PM, Antoine Latter wrote:
>> On Thu, Aug 9, 2012 at 9:56 PM, Christopher Howard
>> <christopher.howard at frigidcode.com> 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
>
>
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