NAME

       MIR::MARC - Intermediate Representation

   DESCRIPTION
       MARC::MIR is not a library, it's a specification for in-memory representation of a MARC
       record with simplcity in mind. The current module comes with a set of helpers to
       manipulate it (i call it MARC::MIR DSL).

       The DSL itself is designed to  be used the more natural way possible. Here are some basic
       exemples (combined with Perlude).

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

           # marcdump

           now {say for_humans from_iso2709} iso2709_records_of 'source.mrc'

           # report the IDs of the 10 first records of the file

           now {
               any_fields {
                   tag eq '001' and say value
               } from_iso2709
           } take 10, iso2709_records_of 'echantillon_ecparis.raw';

           # or

           now {
               $_ = from_iso2709;
               any_fields {
                   tag eq '001' and say value
               }
           } take 10, iso2709_records_of 'echantillon_ecparis.raw';

       Some other modules and documentations are worth to read.

   NAME
       MARC::MIR::Template - is a description format to import/export a MIR from/to a
       datastructures that fits modern formats like JSON or XML (shipped separately).

   NAME
       MARC::MIR::Tutorial - gives basic exemples of use of the MARC::MIR DSL described below.

WARNINGS

       t/* is empty and the API may change (i even i think it's quiet stable on the basics). i
       think the doc is up to date and the stability of MARC::MIR.

       Anyway: waiting for the tests, MARC::MIR runs daily on linux stations (perl 5.12 to 5.17)
       on large amount of data. It is as faster and easier to use than older libraries and is
       designed to get the data back from iso files, no matter the quality of the serialization
       dictionary so for one shot scripts, i'm now more confident in MARC::MIR than i ever was in
       MARC::Record, for example.

MOTIVATION

       I dealt with lot of MARC records in the past (mainly from/to iso2709 files) and was really
       annoyed by the state of art:

       ISO2709 was a clever format when it was invented (more than 40 years ago! older than FTP
       or even UNIX) but the world has changed a so drastic way most of the IT crowd, bred to
       modern serialization formats (YAML, JSON, XML) are clueless when it comes to magnetic
       tapes friendly serializations. Librarians haven't got it since recently.

       As a result, IT people just flee libraries and reinvent information sciences from scratch
       with modern tools fitting the modern interconnected world when librarians are left with
       the rest of us, dead bored programmers using old school tools and bad designed modules
       with painfull OO approach. I don't blame anyone: it's just the way the things gone.

       But if you come back to the roots: A MARC record is a very simple structure so they must
       be simple to manulate. MARC::MIR is an attempt to get the simplicity back.

SPECIFICATION

       so MIR is just an array of array (see man perllol) with very simple rules:

           record       = [ header, [fields] ]
           fields       = controlfield | datafield
           controlfield = [tag,string]
           datafield    = [tag,[subfields],indicators]
           indicators   = [ ind1, ind2 ] # can be represented as a 2 chars fields
           subfields    = [tag,string]

       note that tags are always at the index 0, data always at 1.

       All the indexes that are not used by the spec can be used to store instructions for
       middleware and serializer purposes. there is no convention there.

   Examples
       A MIR control field is a tag and a value.

           [ '001', '1231313145' ]

       A MIR data field

           [ $tag, [@subfield] ]
           [ $tag, [@subfield], "  " ]
           [ $tag, [@subfield], [' ',' '] ]

       A MIR record

           [ '01972cam0a2200541   450' =>
               [ [ '001' => '2344564564' ] # this is the ID
               ,   [ '856'
                   , [ [ q => "jpeg" ]
                     , [ z => "cover from original version" ]
                     , [ u => "http://localhost/img/" ]
                     ]
                   ]
               ]
           ]

DSL

       the use of $_ and thd "(_)" prototype is idiomatic: almost every subs are written to be
       used a very natural way (my hope is librians to write some code).  So we prefer to write

           say for_humans from_iso2709

       than a more pythonic way

           say( for_humans( from_iso2709( $_ )))

   map_*, with_*, any_*, grep_*
       # TODO: maybe an array there ?

   tag, value, indicators
   ISO2709 handling
       # TODO: from|to_iso2709

   CIB handling
       # TODO: from|to_iso2709

Authors

           * Marc Chantreux (eiro) marcc(at)cpan.org
           * You? https://github.com/eiro/p5-marc-mir

KNOWN BUGS

       feedbacks are very welcome. the only known bugs are

            * with_fields needs $_
            * map_datafields can't work
            * *_values? must crash on references