Nice work on a mind-bending puzzle. I refactored it some to combine base cases and whatnot and came up with this probably-too-dense version: 
sub my_make_change {
  my $amount = shift;
  my $coin = shift || -1;
  return(
    map {
       my $n = $_;
       map [ [ $n, $coin ], @$_ ],
           ($n*$coin == $amount
            ? []
            : my_make_change( $amount - $n*$coin, @_ ));
    } (0..$amount/$coin)
  );
}

[download]
The output includes zeroes for any denominations on the left, which coincidentally makes the output tidier (or undesirably verbose, depending on your viewpoint).
Caution: Contents may have been coded under pressure.

In reply to Re: How many ways to make change? by Roy Johnson
in thread How many ways to make change? by tlm

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