1Swim(3) User Contributed Perl Documentation Swim(3)
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6 Swim - See What I Mean?!
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9 This document describes Swim version 0.1.46.
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12 > swim --to=pod doc/MyModule.swim > MyModule.pod
13 my $pod = Swim->new(file => "doc/MyModule.swim")->to_pod;
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17 Swim is a plain text markup language that converts to many formats:
18 · HTML
20 · Rich - Lots of classes and annotations
22 · Sparse - Just the tags and content
24 · Custom - HTML the way you want it
26 · MarkDown
28 · GitHub Flavored Markdown
30 · Pod
32 · Formatted Plain Text
34 · LaTeX
36 · DocBook
38 · Manpage
40 · AsciiDoc
42 · MediaWiki
44 The Swim framework is easily extensible, so adding new outputs is easy.
46 What Makes Swim Different
48 There are already a lot of text-to-html languages in the world. How is
49 Swim different?
50 Here are a few points:
52 · Very rich capabilities:
54 Swim aims to be a feature superset of the other markups since it
56 converts to all of them.
57 Most of the other markups don't support things like multiple
59 paragraphs in a bullet point (like you are reading right now!).
60 · Simple, consistent markup:
62 Even though Swim intends to be very rich, it will use a simple set
64 of syntax idioms to accomplish its tasks. One of my favorite
65 sayings comes from Larry Wall of Perl fame: "Make simple things
66 simple and hard things possible". Swim does just that (hopefully
67 without looking too much like Perl ;).
68 · Extensible:
70 Swim is easy to extend at many levels. You can add new backend
72 formats. You can also define your own markup syntaxes. You can even
73 define sections that parse using a different syntax grammar. For
74 instance, you could inline a markdown section like this:
75 <<< markdown
77 This is [Markdown](http://daringfireball.net/projects/markdown/) text.
78 >>>
79 · Multiple Implementations:
81 Swim is written using the Pegex parser framework. This provides 2
83 very powerful concepts. Firstly, that Swim language is defined in a
84 very simple PEG topdown grammar. That means it is easy to grok,
85 maintain and extend. Second, Pegex parsers work in many languages.
86 That means that you can use Pegex natively in languages like Ruby,
87 JavaScript, Perl, Python and many others.
88 · Comments and blank lines:
90 Most markups don't support comments and eat extra blank lines.
92 These things are useful. Swim not only supports comments, they are
93 part of the data model. ie They get rendered as HTML (or comments
94 in other target languages that support comments). Swim also support
95 throwaway comments, for times when you want to hide part of a
96 document.
97 Syntax Concepts
99 Before diving into the actual markup syntax, let's discuss the concepts
100 that drive the decisions that Swim makes.
101 Most documents are just plain language using letters and numbers and a
103 few punctuation chars like comma, dash, apostrophe, parentheses and
104 colon. Also endings: period, exclamation point and question mark. We
105 leave those alone (at least in the normal prose context).
106 This leaves a bunch of punctuation characters that we can do special
108 things with. Namely: "@#$%^&*_=+|/~[]<>{}". Sometimes context matters.
109 For instance it is very rare for a prose line to start with a period,
110 so we can use that as a markup.
111 The important thing in all this is that we be able to reverse the
113 meaning for edge cases. ie We need a way to make markup characters be
114 viewed as regular characters. Swim uses a backslash before a character
115 to make it not be seen as markup. For instance this text "*not bold*"
116 is not bold because it was written like this: "\*not bold\*".
117 Swim has a document model that views things as blocks and phrases. This
119 is very similar to HTML's DIV and SPAN concepts. Swim views a document
120 as a sequence of top level blocks. Blocks are further subdivided into
121 either a sequence of blocks or a sequence of phrases. Phrases can only
122 be subdivided into more phrases.
123 Consider this example document:
125 A paragraph *is* a block. It gets divided into phrases like 'pure text' and
127 *bold text*. A bold phrase can be divided: *all bold /some italic/*.
128 * Lists are blocks.
130 * Each item is a block.
131 * A sublist is a block.
132 * The text within in contains *phrases*.
133 Common blocks and phrases have an implicit (DWIM) syntax, that reads
135 very natural. For instance a paragraph is just left justified text that
136 is terminated by a blank line. There is also an explicit syntax for
137 blocks and phrases. Every implicit syntax can be written explicitly.
138 For instance, here is an implicit syntax example followed by its
139 explicit equivalent:
140 A paragraph with some *bold text* in it.
142 <<< para
144 A paragraph with some <bold bold text> in it.
145 >>>
146 Two Space Indent
148 Swim uses a 2 space indentation and it is very instrumental to its
150 design. It allows for a very nice and natural embedding of blocks
151 within blocks. Consider this list:
152 * Point one has
154 text on 2 lines
155 * Subpoint a
156 * Point two
157 A paragraph for point 2 followed by some preformatted text:
159 # Code example
160 * Point three
161 As you can see, 2 space indent is very natural here and allows for
163 putting blocks inside blocks in a way that is not available in most
164 markups.
165 Swim Syntax
167 There are 4 sets of syntax to define: block/implicit, phrase/implicit,
168 block/explicit and phrase/explicit. There are also escaping mechanisms.
169 Block/Implicit Syntaxes
171 A paragraph is a contiguous set of plain text lines. It is terminated
173 by a blank line or by another block syntax at that level.
174 To be continued
176
178 Ingy döt Net <ingy@cpan.org>
179
181 Copyright 2014-2017. Ingy döt Net.
182 This program is free software; you can redistribute it and/or modify it
184 under the same terms as Perl itself.
185 See <http://www.perl.com/perl/misc/Artistic.html>
187perl v5.28.1 2017-02-12 Swim(3)