18 Nov
2011
18 Nov
'11
11:10 a.m.
On Fri, Nov 18, 2011 at 1:58 AM, Roman Leshchinskiy
Johan Tibell wrote:
map (\ v -> undefined) == undefined mapKeys (\ k -> undefined) == undefined
Not really related to the question but I don't really understand how these properties can possibly hold. Shouldn't it be:
map (\v -> undefined) x = undefined
And even then, does this really hold for empty maps?
It doesn't hold. It needs the side condition that the map is initially empty. I wonder if there's any function in the API that'd let me express this property (of HOFs) that doesn't require a side condition. I don't think so e.g. insertWith (\old new -> undefined) k v m has a side condition that k is in the map. -- Johan