He seemed astonished when I showed him one line of Perl that demonstrated recursive descent parsing.

Recursive descent parsing in one line of Perl; I'd like to see that?

Admittedly, it is a basic example, although powerful in its implications.

print "good string\n" if $_~~ /^({(?:[^{}]++|(?1))*+})/;
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It tests for proper nesting of brackets, anchored to the beginning of the line. You can try it out:

perl -ne 'print "good string\n" if $_~~ /^({(?:[^{}]++|(?1))*+})/;'
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You can do that like this:

C:\test>perl -nE"my$t; /{/&&++$t or /}/&&--$t for split''; say $t ? $t
+ : 'good string'"
{}
good string
{}}
-1
{{}}
good string
{{}{}}
good string
{{}{}}}
-1
{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{}}}}}}}}}}}}}}}}}}}}}}}}}}}}}
11
{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{}}}}}}}}}}}}}}}}}}}}}}}}}}
14
{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}
+}}}}
6
{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}
+}}}}}}}}}}
good string
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But I wouldn't call it RDP :)

The problem with doing RDP with regex is that you have to match the entire stream with one (possibly (hopefully :) composite) regex. Which is fine for yes/no booleans, but it makes both debugging the regex and reporting where and why parsing errors occur extremely messy if not impossible.

---

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

RIP Neil Armstrong

I think that he was being polite to you ...