For what it's worth, I've taken, for reasons including the tricky handling
in dynamic things, I've taken to defining "unions" in the Thrift or
Protocol Buffer style.  Instead of "union(A,B,C,D)", I do
"struct(union(null, A) a, union(null, B) b, union(null, C) c, union(null,
D) d").  Note that this implies certain storage inefficiencies.  I'm doing
this in RPC-land, which the extra few bytes aren't bothering me.

On Thu, Jun 5, 2014 at 11:00 AM, Grant Overby (groverby) <[EMAIL PROTECTED]
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