Hi Tom,
: Hi Marc.
:
: The Haskell type system can't express a polymorphic natural join.
I can understand that.
: Even the Trex extension to Hugs doesn't quite manage it. That's why
: I'm keen on a further extension: symmetric record catenation. :-)
What I need (and I hacked a quick and dirty version)
is something with the following functionality:
data Table variable value = Table [variable] [[value]]
naturalJoin :: (Ord a,Ord b) =>
Table a b -> Table a b -> Table a b
projection :: (Ord a,Ord b) =>
Table a b -> [a] -> Table a b
: Also, the attached message may be relevant.
Thanks!
[...]
Regards,
Marc van Dongen
