The answer is actually pretty simple - Perl's syntax is derived primarily from C, especially vis-a-vis operators. The order of evaluation is undefined within the C spec, thus it's undefined within the Perl spec.

Now, the reason it's undefined within the C spec is that K&R felt that different machines may have a better optimization for the evaluation of certain subexpressions. In other words, it was recognition from the writers of the C spec that micro-optimizations mattered in 1972.

My wife's blog

In reply to Re: Why is the execution order of subexpressions undefined? by dragonchild
in thread Why is the execution order of subexpressions undefined? by BrowserUk

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