NAME

    Swim - See What I Mean?!

VERSION

    This document describes Swim version 0.1.37. ";

SYNOPSIS

        > swim --to=pod doc/MyModule.swim > MyModule.pod
    
        my $pod = Swim->new->(file => "doc/MyModule.swim")->to_pod;

DESCRIPTION

    Swim is a plain text markup language that converts to many formats:

      * HTML

	* Rich - Lots of classes and annotations

	* Sparse - Just the tags and content

	* Custom - HTML the way you want it

      * MarkDown

	* GitHub Flavored Markdown

      * Pod

      * Formatted Plain Text

      * LaTeX

      * DocBook

      * Manpage

      * AsciiDoc

      * MediaWiki

    The Swim framework is easily extensible, so adding new outputs is easy.

 What Makes Swim Different

    There are already a lot of text-to-html languages in the world. How is
    Swim different?

    Here are a few points:

      * Very rich capabilities:

      Swim aims to be a feature superset of the other markups since it
      converts to all of them.

      Most of the other markups don't support things like multiple
      paragraphs in a bullet point (like you are reading right now!).

      * Simple, consistent markup:

      Even though Swim intends to be very rich, it will use a simple set of
      syntax idioms to accomplish its tasks. One of my favorite sayings
      comes from Larry Wall of Perl fame: "Make simple things simple and
      hard things possible". Swim does just that (hopefully without looking
      too much like Perl ;).

      * Extensible:

      Swim is easy to extend at many levels. You can add new backend
      formats. You can also define your own markup syntaxes. You can even
      define sections that parse using a different syntax grammar. For
      instance, you could inline a markdown section like this:

          <<< markdown
          This is [Markdown](http://daringfireball.net/projects/markdown/) text.
          >>>

      * Multiple Implementations:

      Swim is written using the Pegex parser framework. This provides 2
      very powerful concepts. Firstly, that Swim language is defined in a
      very simple PEG topdown grammar. That means it is easy to grok,
      maintain and extend. Second, Pegex parsers work in many languages.
      That means that you can use Pegex natively in languages like Ruby,
      JavaScript, Perl, Python and many others.

      * Comments and blank lines:

      Most markups don't support comments and eat extra blank lines. These
      things are useful. Swim not only supports comments, they are part of
      the data model. ie They get rendered as HTML (or comments in other
      target languages that support comments). Swim also support throwaway
      comments, for times when you want to hide part of a document.

 Syntax Concepts

    Before diving into the actual markup syntax, let's discuss the concepts
    that drive the decisions that Swim makes.

    Most documents are just plain language using letters and numbers and a
    few punctuation chars like comma, dash, apostrophe, parentheses and
    colon. Also endings: period, exclamation point and question mark. We
    leave those alone (at least in the normal prose context).

    This leaves a bunch of punctuation characters that we can do special
    things with. Namely: @#$%^&*_=+|/~[]<>{}. Sometimes context matters.
    For instance it is very rare for a prose line to start with a period,
    so we can use that as a markup.

    The important thing in all this is that we be able to reverse the
    meaning for edge cases. ie We need a way to make markup characters be
    viewed as regular characters. Swim uses a backslash before a character
    to make it not be seen as markup. For instance this text "*not bold*"
    is not bold because it was written like this: "\*not bold\*".

    Swim has a document model that views things as blocks and phrases. This
    is very similar to HTML's DIV and SPAN concepts. Swim views a document
    as a sequence of top level blocks. Blocks are further subdivided into
    either a sequence of blocks or a sequence of phrases. Phrases can only
    be subdivided into more phrases.

    Consider this example document:

        A paragraph *is* a block. It gets divided into phrases like 'pure text' and
        *bold text*. A bold phrase can be divided: *all bold /some italic/*.
    
        * Lists are blocks.
        * Each item is a block.
          * A sublist is a block.
          * The text within in contains *phrases*.

    Common blocks and phrases have an implicit (DWIM) syntax, that reads
    very natural. For instance a paragraph is just left justified text that
    is terminated by a blank line. There is also an explicit syntax for
    blocks and phrases. Every implicit syntax can be written explicitly.
    For instance, here is an implicit syntax example followed by its
    explicit equivalent:

        A paragraph with some *bold text* in it.
    
        <<< para
        A paragraph with some <bold bold text> in it.
        >>>

  Two Space Indent

    Swim uses a 2 space indentation and it is very instrumental to its
    design. It allows for a very nice and natural embedding of blocks
    within blocks. Consider this list:

        * Point one has
          text on 2 lines
          * Subpoint a
        * Point two
    
          A paragraph for point 2 followed by some preformatted text:
            # Code example
        * Point three

    As you can see, 2 space indent is very natural here and allows for
    putting blocks inside blocks in a way that is not available in most
    markups.

 Swim Syntax

    There are 4 sets of syntax to define: block/implicit, phrase/implicit,
    block/explicit and phrase/explicit. There are also escaping mechanisms.

  Block/Implicit Syntaxes

    A paragraph is a contiguous set of plain text lines. It is terminated
    by a blank line or by another block syntax at that level.

    To be continued

AUTHOR

    Ingy döt Net <ingy@cpan.org>

COPYRIGHT AND LICENSE

    Copyright 2014-2015. Ingy döt Net.

    This program is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself.

    See http://www.perl.com/perl/misc/Artistic.html

