Re: Compiler writers will love this language

ericmuttta@email.com (Eric) wrote:


[snip]


>I have often wondered how specifying evaluation order impacts
>implementation. The arguments I have heard for it are:
>
>- it allows consistency between different compilers hence allowing
>code portability between compilers
>
>- it allows one to take advantage of evaluation order in expressions
>
>The second one sounds dubious at first but thinking about it, we
>always rely on our code executing from top to bottom and write the
>code so its dependant on that execution order. So then, is it
>unresonable to specify that evaluation order is left-to-right (or
>vice-versa)? If so, what are the arguments for leaving the order
>undefined? (I have heard something related to efficiency and register
>allocation during procedure invocations, but no explanation was
>given).


          Reversing that, you can take advantage of evaluation order. It
might be possible to optimise out constants by reordering evaluation:


                    #define OFFSET1 5
                    #define OFFSET2 15
                    ...
                    ... someint + OFFSET1 + OFFSET2 ...


          The natural order for most programmers appears to be variable
followed by constant(s).


[snipped previous]


Sincerely,


Gene Wirchenko

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