Data.Map.deleteAt broken with index 0

[guest]

Take a look at this ghci session:

Prelude> :m Data.Map
Prelude Data.Map> Data.Map.deleteAt 0 (Data.Map.fromList [(0::Int, 0::Int), (1,1), (2, 2), (3, 3)])
fromList []
Prelude Data.Map> Data.Map.elemAt 0 (Data.Map.fromList [(0::Int, 0::Int), (1,1), (2, 2), (3, 3)])
(0,0)

In other words, deleteAt with index 0 deletes *everything* in the map, not just the first element in it.

Prelude Data.Map> Data.Map.deleteAt 1 (Data.Map.fromList [(0::Int, 0::Int), (1,1), (2, 2), (3, 3)])
fromList [(0,0),(2,2),(3,3)]

That appears to work as it should. It seems that there is something wrong with an index of 0.

[guest]

it looks like updateAt also has this problem.

[guest]

It's not just index 0, that's just an easy way to replicate it.

Step through the indices and you'll find quite a few wrong results.

[igloo]

Thanks for the report.

This works in the HEAD for me. It sounds like another example of  http://haskell.org/pipermail/libraries/2007-July/007785.html