Mostly unique

Peter Schachte pets at
Mon Dec 7 14:12:06 AEDT 1998

Is there a difference between mostly unique input and unique input?
As far as I can see, a promise not to copy a pointer to any part of a
term should not depend on how many solutions that predicate has, so I
would argue there isn't a difference.  The problem with multiple
solutions comes up when one wants to destructively modify something,
which requires both deadness and uniqueness.

This then raises the question: is there a useful difference between
the unique and mostly unique insts?  I'm not as sure about this, but I
don't see this difference either.  If there isn't a meaningful
difference, I think it would be a good thing to remove that
distinction from the language.

Peter Schachte                | PL/1, "the fatal disease", belongs more to
mailto:pets at       | the problem set than to the solution set. |     -- E. W. Dijkstra 
PGP: finger pets at | 

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