On Sun, Feb 05, 2012 at 03:02:35PM +0100, Ralf Hemmecke wrote:
>> But here is a small example:
>> the below package DChar1 uses dropWhile and span of the package
>> DList1.
>> For dropWhile, the comiler insists on adding $ DList1(Character)
>> (otherwise reports of a certain error).
>
> [snip]
>
>> )abbrev package DCHAR1 DChar1
>> DChar1() : with
>> foo : List Character -> Product(List Character, List Character)
>> ==
>> add
>> foo(xs : List Character) :
>> Product(List Character, List Character) ==
>>
>> xs0 := dropWhile(x +-> x = space, xs) $ DList1(Character)
>> -- $ cannot be omitted
>> span(x +-> not digit?(x), xs0)
>
> If you remove the line starting with xs0 and replace xs0 by xs in the
> next line, the compiler also insists on adding $DList1(Character) for
> span.
>
> Obviously, using $DList1(Character) for package calling dropWhile means
> to import the functions from DList1(Character).
>
> So your function foo would also work if you introduce
>
> import DList1(Character)
>
> just before the line "xs0 := ...".
>
> I'm not sure, however, whether I like that package calling should import
> all other functions from that package. I tend to dislike it and consider
> it a compiler bug.
Is there a way to import only a couple of chosen items from a package?
I Haskell, we write, for example,
import Foo (A(..), T(..), foo)
to import from the _module_ Foo a class (category) A, a data type T,
and a function foo. Only these three items will be imported
(+ all the class instances defined in Foo for the data type T)
(I guess, a messy job to correctly implement all this in the compiler,
even writing it in Haskell).
Generally, it would be natural to have a similar possibility in Spad
(I do not know, may be it has such).
Regards,
------
Sergei
[email protected]
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