Beefy Boxes and Bandwidth Generously Provided by pair Networks
good chemistry is complicated,
and a little bit messy -LW

Comment on

( #3333=superdoc: print w/replies, xml ) Need Help??

is rather extravagant ... would produce the same result. Am I missing something?

Not really, although, a clarity argument could be made

map is mostly used for generating lists, so sometimes it feels like the wrong tool for counting ( is the use of map in a void context deprecated ? , What's wrong with using grep or map in a void context? )

tobyink improves clarity by generating a list of counts and adding/summing them (makes an array of matches, scalar array is count), map made a list, feels good :)

you rely on generating a list of matches ( m//g) , and that map in scalar context returns a count

Is there a performance advantage? Penalty? Was map-in-scalar as expensive as map-in-void (before perlv5.8.1)?
It doesn't really matter as the reason for using map over foreach is clarity/brevity/tradition. The basic intent echoed in all the manuals and books, map for transforming lists, grep for filtering lists, foreach(for) for counting (iterating).

Compare the "three"

my @dipept = qw( AABBCC AABBAA ); use v5.12; use List::Util qw(sum); my $count1 = sum map { scalar(my @r = /AA/g) } @dipept; my $count2 = scalar map { /AA/g } @dipept; my $count3 = 0; $count3 += /AA/g for @dipept; my $count5 = 0; map { $count5 += /AA/g } @dipept; my $count6 = 0; grep { $count6 += /AA/g } @dipept;

If you're thinking in terms of map and grep, thinking perlishly, then you write it like it makes the most sense to you, feels most natural, reads instantly and effortlessly (reads like breathing), needs no thought ...

so what you're missing, is tobyink's brains

In reply to Re^3: Using grep in a scalar context (brains) by Anonymous Monk
in thread Using grep in a scalar context by newbie1991

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 all is quiet...

    How do I use this? | Other CB clients
    Other Users?
    Others studying the Monastery: (4)
    As of 2018-03-21 02:07 GMT
    Find Nodes?
      Voting Booth?
      When I think of a mole I think of:

      Results (263 votes). Check out past polls.