Any reason the libaries don't define:
class HasNull a where null::a->Bool
class HasEmpty a where empty::a
I find that I sometimes switch between using lists, sets, or tables as
my collection type and the forced import qualifification for generic
collection operations seems annoying.
-Alex-
On Thu, 2 Jun 2005, Robert van Herk wrote:
6. My module applies Data.Set.null (s :: Set a),
and null (xs :: [a]).
Why ghc reports of the clash with GHC.List.null ?
Is GHC.List same as old List library module?
Should I write
import GHC.List (genericLength, null)
instead of import List (genericLength)
?
As the documentation reads:
This module is intended to be imported qualified, to avoid name clashes with
Prelude
<http://www.haskell.org/ghc/docs/latest/html/libraries/base/Prelude.html>
functions. eg.
import Data.Set as Set
So, you should write:
import qualified Data./x/ as /y/
Now, no name clashes will occur. However, you will have to write /y/.null to
access null in /x/, for example:
import qualified Data.Set as Set
if (Set.null ...) then ... else ...
Regards,
Robert
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