Thats what you want? 
my $sq = sub { $_[0]**2 };
my $id = sub { $_[0] };
 
sub sum {
  my ($a,$b,$func) =@_;
  $func //= $id;
  my $sum;
  $sum += $func->($_)  for ($a..$b);
  return $sum;
}
 
sub sum_sq{ sum($_[0],$_[1],$sq)}
 
$,=",";
print sum(3,5),sum_sq(3,5);        # 12,50

[download]

I skipped the &next sub for integer stepping, but shouldn't be to difficult with a while loop checking $a<$b.

(UPDATE: I'm puzzled... if "&next" is necessary to get the next element of an iterator one must also provide a &cmp for checking $a<$b in the loop-condition)

Better avoid Lisp-recursion in Perl, when you can use "real" loops, we don't automatically optimize them to loops like Lisp does.

Cheers Rolf

In reply to Re: PERLISP meditations by LanX
in thread PERLISP meditations by protist

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.