#
# This software is Copyright 2005 by Elsevier Inc.  You may use it
# under the terms of the license at http://perl.plover.com/hop/LICENSE.txt .
#



###
### memoize-normalize
###

## Chapter 3 section 7

sub memoize {
  my ($func, $keygen) = @_;
  my %cache;
  my $stub = sub {
    my $key = $keygen ? $keygen->(@_) : join ',', @_;
    $cache{$key} = $func->(@_) unless exists $cache{$key};
    return $cache{$key};
  };
  return $stub;
}