[Swift-devel] Functionality request: best effort execution

[Ben Clifford]

One way of putting in ambiguity here is something like the AMB(iguous) 
operator, which looks very similar to Karajan's race behaviour.

   a AMB b evaluates to either a or b but its not defined which and so the 
     runtime can pick which.

That has no particular preference for a result, though in Tibi's use case 
one of the results is probably preferred.

You could change the semantics so that it returns a unless a fails in 
which case it evaluates and returns b, unless b fails in which case the 
expression fails to evaluate.

Both of the above descriptions can be extended to more than two operands 
in a natural way.

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