[Haskell-beginners] List syntax

[Christian Maeder]

In fact there is no ambiguity (but ghc does not bother to resolve this).

No legal expression can start with a (qualified) symbol like ".", so 
since you used square brackets rather than round ones (to make a 
section) the resolution could be unique (by accepting an otherwise 
illegal source).

C.

Am 27.07.2012 17:01, schrieb Lyndon Maydwell:
> On Fri, Jul 27, 2012 at 10:52 PM, Stayvoid <stayvoid at gmail.com> wrote:
>> Thanks.
>>
>> P.S. I think that you should send your answer to the list to show the
>> others that this issue is solved.
>
>
> Ah, I thought I replied to all. Well, here is my reply for the record :-)
>
>
> Here's what I'm describing in a GHCi session:
>
>>   λ [LT..GT]
>>
>> <interactive>:2:2:
>>      Failed to load interface for `LT'
>>      Use -v to see a list of the files searched for.
>>
>> <interactive>:2:2:
>>      A section must be enclosed in parentheses thus: (LT.. GT)
>
> I'm assuming that this was the error that you encountered when you
> tried to use the syntax [LT..GT].
>
> In my example I used a renamed module, but this also makes sense for a
> module imported the usual way. I renamed the module so you could see
> directly how an ambiguity could occur for 'LT'.
>
> If you import a module you can rename it by using the 'as' keyword, in
> this case, 'LT'. There is now an ambiguity between 'LT' = "less than"
> and 'LT' = "Data.List".
>
>>   λ import qualified Data.List as LT
>>
>>   λ :i LT.map
>> map :: (a -> b) -> [a] -> [b]         -- Defined in `GHC.Base'
>
> Here is a demonstration of the renamed module in action.
>
>>   λ :i LT..
>>
>> Top level:
>>      Failed to load interface for `LT'
>>      Use -v to see a list of the files searched for.
>
> And here is what I think is causing your error to be thrown - The
> symbol '.' is being searched for in module LT in the same manner that
> 'map' was in the previous example, now given that there is no LT
> module, it is failing.
>
> This ambiguity might seem annoying, but it's not too bad since you can
> just put some spaces in to resolve it.
>
> _______________________________________________
> Beginners mailing list
> Beginners at haskell.org
> http://www.haskell.org/mailman/listinfo/beginners
>