[MLton-user] Re: [polyml] Order of evaluation of arguments to a
jeremy at rsise.anu.edu.au
Thu Aug 18 17:30:11 PDT 2011
I recall reading somewhere (can't find it now) that Moscow ML is
incorrect, but that it was done deliberately for efficiency reasons, the
thinking being that it would be unlikely to be an issue in practice.
That is (as I recall), in f x1 x2 x3 (f not an application)
it will evaluate _all_ the arguments before evaluating _any_ of the
Peter - is this correct ?
Ivan Tomac wrote:
> Is the following code supposed to print 1 followed by 2 or 2 followed by 1?
> val _ = (fn () => (print "1\n"; fn x => x)) () (print "2\n"; ())
> In SML/NJ, MLton and PolyML it does the former, while in Moscow ML it
> does the latter. Is this specified somewhere in the standard? I
> noticed equivalent code in OCaml behaves the way Moscow ML does which
> is not very surprising seeing how Moscow ML was based on Caml Light.
> Could this be a bug in Moscow ML?
> The following code works the same in all 4 SML compilers (but
> different in OCaml):
> val _ = (print "1\n"; 1) + (print "2\n"; 2)
> It seems to me like SML/NJ, MLton and PolyML evaluate all function
> arguments left to right, OCaml evaluates them right to left, and
> Moscow ML seems inconsistent.
> polyml mailing list
> polyml at inf.ed.ac.uk
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