Re: Unary operator after binary operator: legal or not? => Compiler Error

["Charles Lindsey" <chl@clerew.man.ac.uk>]

In <wccy7gwa7sh.fsf@shell01.TheWorld.com> Robert A Duff <bobduff@shell01.TheWorld.com> writes:

>"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:

>> On Tue, 31 Jul 2007 11:05:05 -0400, Robert A Duff wrote:
>>
>>> If there's a bug, it's a bug in the language definition.  ;-)
>>
>> But not in this place. There should be user-defined subtypes, which would
>> eliminate any need in tricks like defining nonsensical "+", just in order
>> to have a shortest possible name for the conversion, which otherwise should
>> be automatic.

>Agreed.

>But don't you think:

>    X * -3

>ought to be legal (no user-defined operators in sight)?

Interestingly, that example works in ALGOL 68, which generally speaking is
as pernickety a language as you are likely to get.

--x works too. Essentially, all the monadic operators have a higher
preference than the dyadic ones.

The only case where this turns out to be a little odd is

   -2^2
which is to be contrasted with the effect of
   x-2^2
and even there it is only the method of parsing that changes. The result
is actually the same.

(INT x = 2
;print((x*-3, --x,-2^2,x-2^2))
)
 

which prints

STARTING ...
         -6          +2          +4          -2
 ... AND YET ANOTHER ALGOL68 PROGRAM RUNS TO COMPLETION
 CPU  0.17



>- Bob
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