NAME

       MARC::MIR::Tutorial - Tutorial for MARC::MIR DSL

   the DSL
       to make things more readable and less error prone, we also add a DSL. Every keywords of
       this DSL works the same way. FIXME : explain.

       also, iso2709_records_of is an helper that stream the records of an ISO2709 formatted
       file.

   some examples
       the perfect boilerplate

           use autodie;
           use Modern::Perl;
           use Perlude;
           use MARC::MIR;

       print all the ids of the records (assuming the id is in 001, the common case)

           now    { say record_id from_iso2709 } iso2709_records_of "biblio.marc";

       or

           marawk { say $ID } "biblio.marc";

       remove every 9.. fields

           now {
               $_ = from_iso2709;
               with_fields { @$_ = grep { (tag) !~ /^9/ } @$_ };
               print to_iso2709;
           } iso2709_records_of "biblio.marc";

       every 856$q must be jpeg

           now {
               $_ = from_iso2709;
               map_fields {
                   tag eq '856' and map_subfields {
                       (tag) eq 'z' and with_value { $_ = 'jpeg' }
                   }
               }
               with_fields { @$_ = grep_fields { (tag) !~ /^9/ } @$_ };
           } iso2709_records_of "biblio.marc";

       or

           marawk { map_values { $_ = 'jpeg' } [qw< 856 z >] } "biblio.marc"

       collect every 856$z by id

           use Modern::Perl;
           use YAML;
           use MARC::MIR;

           my %seen;
           marawk {
               map_values { push @{ $seen{$ID} }, $_ } [qw< 856 z >]
           } "data/*.RAW";
           say YAML::Dump \%seen;

   marawk
       # TODO: