use strict;
use warnings;
use feature 'say';

use Math::GSL qw/ :all /;
use Math::GSL::Permutation qw/ :all /;

{ 
my $p = gsl_permutation_calloc( 5 );

say join '', map { gsl_permutation_get( $p, $_ )} 0 .. 4;
gsl_permutation_next( $p );
say join '', map { gsl_permutation_get( $p, $_ )} 0 .. 4;

my $f = gsl_fopen( 'gsl_test', 'w' );
gsl_permutation_fwrite( $f, $p );
gsl_fclose( $f );

gsl_permutation_free( $p );
}

say "\n...and next day..\n";

{ 
my $p = gsl_permutation_calloc( 5 );

my $f = gsl_fopen( 'gsl_test', 'r' );
gsl_permutation_fread( $f, $p );
gsl_fclose( $f );

say join '', map { gsl_permutation_get( $p, $_ )} 0 .. 4; # one repeat from yesterday
gsl_permutation_next( $p );
say join '', map { gsl_permutation_get( $p, $_ )} 0 .. 4; # etc...

gsl_permutation_free( $p );
}

__END__

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...and next day..

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