Parentheses are different from |..|, since you can arbitrarily nest them without ambiguity.

((( no )ambiguity)here)
()( no )ambiguity(here)
|||some|ambiguity|here|
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It looks like you've realized this yourself. It's cute how now you seem to be advocating the two-character (| .. |) instead of your original suggestion. Was your original suggestion dumb?

If you think a programming language should correspond 1-to-1 to mathematical notation, you're going to be disappointed as soon as you get past 8th grade algebra. How do you suggest I code my double-integral or infinite summation? Mathematical notation uses integral signs and a capital sigma. Perl doesn't, so is it dumb? The point is that Perl is a programming language, not a symbolic math calculator.