On 11/02/2017 09:51 PM, Anthony Clayden wrote:
I'm curious what the full signature would look like. Here's my guess:
fun natJoin [ t1' :: {Type} ] [ t1_2 :: {Type} ] [ t2' :: {Type} ]
[ t1' ~ t1_2 ] [ t1' ~ t2' ] [ t1_2 ~ t2' ]
( t1 : $( t1' ++ t1_2 ) ) ( t2 : $( t1_2 ++ t2' ) )
= ??
One possibility is:
t1 ++ (t2 --- t1_2)
It's not clear to me what result type you expect, though.
And how would I invoke it? With those three `~` constraints, does that need
natJoin ! ! ! r1 r2
And can Ur figure out the rest?
Disjointness proofs are implicit by default, so just
natJoin r1 r2
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