use strict;
use warnings;
use Data::Dumper;
use threads;


my $slow_matches_b = sub { sleep 1;
                           return unless $_[0];
                           return 1 if $_[0] =~ /b/;
                         };
my $test_strings = [ ('blee','blah','bloo', 'qoo', 'fwee' ) ];

parallel_map($slow_matches_b,$test_strings);


sub serial_map
{
    my $function = shift;
    my $data = shift;
    
    my @results = map { $slow_matches_b->($_) } @$test_strings;
    print Dumper \@results;
}


sub parallel_map
{
    my $function = shift;
    my $data = shift;
    
    #
    #    assign keys to each data element
    #
    my %hash_input;
    for ( 0..( @$data-1) )
    {
        $hash_input{$_} = $$data[$_];
    }

    
    #
    #    run each data element in separate thread
    #
    my @threads;
    for ( keys %hash_input )
    {
        my $t = threads->create( sub { map_element($_, $function, $has
+h_input{$_} ) } );
        push @threads, $t;
    }
    
    
    #
    #    wait for threads to return ( this implementation is bound by 
+slowest thread )
    #
    my %results = map { %{$_->join()}; } @threads;
    print Dumper \%results;
}


sub map_element
{
    my $key = shift;
    my $function = shift;
    my $data = shift;
    
    
    return { $key => $function->($data) };
}
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