It will be a problem if you are running under strict. However, if the caller sets up $c as a package variable it will work.

sub map_triples(&@) {
  my $f = shift;
  my @res;

  no strict 'refs';
  my $caller = caller;
  local(*{$caller."::a"}) = \my $a;
  local(*{$caller."::b"}) = \my $b;
  local(*{$caller."::c"}) = \my $c;

  push @res, $f->($a,$b,$c) while ($a, $b, $c) = splice @_, 0, 3;
  return @res;
}

use 5.010;
use warnings;
use strict;
our $c;

say for map_triples { $a + $b + $c } 1..12;
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