21 Jun
2008
21 Jun
'08
9:51 a.m.
Jamie Brandon wrote:
Why not just use
class (Ord k, GMap map k) => OrderedGMap map k where
Most of the maps I will be implementing will respect the ordering that would be derived by GHC, regardless of the actual Ord instance. There is no way, in general, to derive a trie that respects an existing Ord instance but I still want to expose the bytewise ordering in the trie.
Well, you could use a newtype for the key, when necessary. But does that suffer from 1. the risk of accidentally not using a newtype? 2. is it an inconvenience to the users of the map? I can't tell... Is it a bad idea to require an Ord context even if you don't use it? It could supply a default method... but would surely confuse people like (1) above. -Isaac