Am Dienstag, 31. Mai 2005 14:05 schrieben Sie:

On Tue, 31 May 2005, Daniel Fischer wrote: (snip)

...

The module Set has undergone major changes - look at the code and admire, if you have it. Formerly sets were implemented as 'FiniteMap's, now as size-balanced trees. Formerly there was a function called 'mapSet', now

(snip)

I'm puzzled: wasn't the FiniteMap version also some form of size-balanced tree?

-- Mark

Indeed, I have looked at the sources and found out that now the implementations of 'Set' and 'Map' are basically the same. Presumably the new implementation of size-balanced trees is (much?) more efficient than the old one from 'FiniteMap'. Cheers, Daniel

On 31-May-2005, Daniel Fischer wrote:

Am Freitag, 27. Mai 2005 02:06 schrieb Shiqi Cao:

...

I tried to port some code from ghc 6.2 to ghc 6.4, but I got the following error

PrelExts.lhs:41:25: Ambiguous occurrence `map' It could refer to either `GHC.Base.map', imported from Data.List at PrelExts.lhs:11:0-15 or `Data.Set.map', imported from Data.Set at PrelExts.lhs:10:0-14

The following is the first part of the code

module PrelExts where

import Data.FiniteMap import Data.Set import Data.List import IO

There is no problem under ghc 6.2. What should I do? ... To solve your problem, use import controls, for example

import Data.Set hiding (map) import qualified Data.Set as Set

will do fine.

That code only compiles with ghc 6.4, and won't compile with ghc 6.2: you'll get an error for the "hiding (map)" part, because in 6.2 Data.Set does not contain a "map" function. If you want code that compiles with both 6.2 and 6.4 and does not give any warnings with "ghc -Wall", then I think you'll need to use qualified imports, i.e. just the second line above. -- Fergus J. Henderson | "I have always known that the pursuit Galois Connections, Inc. | of excellence is a lethal habit" Phone: +1 503 626 6616 | -- the last words of T. S. Garp.