Beefy Boxes and Bandwidth Generously Provided by pair Networks
Welcome to the Monastery

Comment on

( #3333=superdoc: print w/ replies, xml ) Need Help??
Actually Perl 6 is even harder to (statically) parse than Perl 5, because it is much easier to change the syntax.

You can, for example, introduce new operators very easily:

multi sub prefix:<foo> (Str $a) { return $a eq "foo" ?? "bar" !! "foo"; }

This will define an unary prefix operator that takes one string as an argument. When somebody writes

foo "foo";

You can't know if that's a method call or a call to an operator. You'd think it makes no difference - but wait until precedence comes into the play:

BEGIN { eval " multi * prefix:<foo> (Str $a) is tighter(&infix:<~>) { return $a eq 'foo' ?? 'bar' !! 'foo'; "; } # and later in the code: foo "fo" ~ "o";

If that foo parsed as a sub call the precedence is lower than that of the concatenation ~, and the other way round if it's parsed as an operator.

This is quite a complicated example, but there are much easier ones with "real" macros. (But since no implemenation really implements macros by now, I don't really know much about them).

In reply to Re^3: Perl Cannot Be Parsed: A Formal Proof by moritz
in thread Perl Cannot Be Parsed: A Formal Proof by Jeffrey Kegler

Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":

  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.
  • Log In?

    What's my password?
    Create A New User
    and the web crawler heard nothing...

    How do I use this? | Other CB clients
    Other Users?
    Others examining the Monastery: (7)
    As of 2015-11-29 03:02 GMT
    Find Nodes?
      Voting Booth?

      What would be the most significant thing to happen if a rope (or wire) tied the Earth and the Moon together?

      Results (746 votes), past polls