Here's a somewhat more efficient splicer that is almost as fast as the shifter function:

sub s2 {
  my @r2;
  while (@_) {
    push @r2, [ splice @_, 0, 2 ];
  }
  return \@r2;
}
[download]

This is faster than splicer() because it doesn't have the overhead of assigning the chunks to a temporary array.

By removing the overhead of entering a block on each iteration, it'll be even faster:

sub s2 {
  my @r2;
  push @r2, [ splice @_, 0, 2 ] while @_;
  return \@r2;
}
[download]

As fast as the unaltered shifter() to be precise (but of course shifter() would still win if it were altered in the same way).

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