But in this production, there're only 3 elements on the right hand side, and I don't see what $4 refers to...

Ok, here is more guessing, if we're talking about GRAMPROG  remember stmtseq and 


remember: /* NULL */ /* start a full lexical scope */
{ $$ = block_start(TRUE); }
;

stmtseq : /* NULL */
{ $$ = (OP*)NULL; }
| stmtseq fullstmt
{ $$ = op_append_list(OP_LINESEQ, $1, $2);
PL_pad_reset_pending = TRUE;
if ($1 && $2)
PL_hints |= HINT_BLOCK_SCOPE;
}
;

[download]
then surely $$ = op_append_list(OP_LINESEQ, $1, $2); becomes $2, $3, $4, right?

:)

In reply to Re^3: Where does $4 come from here? by Anonymous Monk
in thread Where does $4 come from here? by PerlOnTheWay

Title:
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, details, 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, summary, 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.