On Tue, 24 May 2005, Ross Paterson wrote:
On Mon, May 23, 2005 at 10:22:38PM +0200, Benjamin Franksen wrote:
A agree completely. Almost all of the functions in Data.Seq have the same name and type signature (modulo the data type) and provide the same functionality as the corresponding ones for lists (in the Prelude). A type class Sequence to capture these common features would be great. It would also mean we can import module Sequence unqualified. A problem is that the names conflict with the ones from the Prelude, so that this style can only be used when hiding all the list stuff from Prelude.
This can't be fixed by adding a new class. We can't change the type of Prelude.length, and that includes generalizing it. The only alterative to hiding/qualification is to give our functions different names.
What is so bad about qualification? Although it might be cumbersome for everyday functions like 'map' and infix operators it's good style for any other functions. With qualification a user module would look like import qualified SomeGoodNameForASequenceClassModule as GenSeq import qualified Data.Sequence as Seq filterEven :: GenSeq.C s => s Int -> s Int filterEven = GenSeq.filter even filterEven' :: Seq.T Int -> Seq.T Int filterEven' = GenSeq.filter even