On Wed, Apr 13, 2011 at 2:49 AM, Andreas Rossberg <rossb...@mpi-sws.org> wrote: > On Apr 13, 2011, at 01:49, Michael Norrish wrote: >> >> Poly 5.3 rejects >> >> datatype foo = bar of string >> >> fun f x = let >> val bar as y = 3 >> in >> bar + x >> end >> >> MLton 20091212~svn accepts it. >> >> Who's right? > > Mlton, although this is arguably a design bug of the language.
I was going to conclude that Poly/ML is right. I don't see why rule (43) applies to the "bar as y" pattern; it is not the case that "bar \notin Dom(C)" (because "bar" is in scope) and it is not the case that "is of C(vid) = v" (because "bar" has constructor status). MLton omits those two antecedents in its implementation of "as"-pattern elaboration. (Similarly, HaMLet omits them.) On the other hand, "val rec bar as y = fn() => 3" would allow changing the identifier status of "bar" (rule (26) and comment). _______________________________________________ polyml mailing list polyml@inf.ed.ac.uk http://lists.inf.ed.ac.uk/mailman/listinfo/polyml
