1Swim(3) User Contributed Perl Documentation Swim(3)
2<<<cpan-head>>>
6
8 > swim --to=pod doc/MyModule.swim > MyModule.pod
9 my $pod = Swim->new(file => "doc/MyModule.swim")->to_pod;
11
13 Swim is a plain text markup language that converts to many formats:
14 • HTML
16 • Rich - Lots of classes and annotations
18 • Sparse - Just the tags and content
20 • Custom - HTML the way you want it
22 • MarkDown
24 • GitHub Flavored Markdown
26 • Pod
28 • Formatted Plain Text
30 • LaTeX
32 • DocBook
34 • Manpage
36 • AsciiDoc
38 • MediaWiki
40 The Swim framework is easily extensible, so adding new outputs is easy.
42 What Makes Swim Different
44 There are already a lot of text-to-html languages in the world. How is
45 Swim different?
46 Here are a few points:
48 • Very rich capabilities:
50 Swim aims to be a feature superset of the other markups since it
52 converts to all of them.
53 Most of the other markups don't support things like multiple
55 paragraphs in a bullet point (like you are reading right now!).
56 • Simple, consistent markup:
58 Even though Swim intends to be very rich, it will use a simple set
60 of syntax idioms to accomplish its tasks. One of my favorite
61 sayings comes from Larry Wall of Perl fame: "Make simple things
62 simple and hard things possible". Swim does just that (hopefully
63 without looking too much like Perl ;).
64 • Extensible:
66 Swim is easy to extend at many levels. You can add new backend
68 formats. You can also define your own markup syntaxes. You can even
69 define sections that parse using a different syntax grammar. For
70 instance, you could inline a markdown section like this:
71 <<< markdown
73 This is [Markdown](http://daringfireball.net/projects/markdown/) text.
74 >>>
75 • Multiple Implementations:
77 Swim is written using the Pegex parser framework. This provides 2
79 very powerful concepts. Firstly, that Swim language is defined in a
80 very simple PEG topdown grammar. That means it is easy to grok,
81 maintain and extend. Second, Pegex parsers work in many languages.
82 That means that you can use Pegex natively in languages like Ruby,
83 JavaScript, Perl, Python and many others.
84 • Comments and blank lines:
86 Most markups don't support comments and eat extra blank lines.
88 These things are useful. Swim not only supports comments, they are
89 part of the data model. ie They get rendered as HTML (or comments
90 in other target languages that support comments). Swim also support
91 throwaway comments, for times when you want to hide part of a
92 document.
93 Syntax Concepts
95 Before diving into the actual markup syntax, let's discuss the concepts
96 that drive the decisions that Swim makes.
97 Most documents are just plain language using letters and numbers and a
99 few punctuation chars like comma, dash, apostrophe, parentheses and
100 colon. Also endings: period, exclamation point and question mark. We
101 leave those alone (at least in the normal prose context).
102 This leaves a bunch of punctuation characters that we can do special
104 things with. Namely: "@#$%^&*_=+|/~[]<>{}". Sometimes context matters.
105 For instance it is very rare for a prose line to start with a period,
106 so we can use that as a markup.
107 The important thing in all this is that we be able to reverse the
109 meaning for edge cases. ie We need a way to make markup characters be
110 viewed as regular characters. Swim uses a backslash before a character
111 to make it not be seen as markup. For instance this text "*not bold*"
112 is not bold because it was written like this: "\*not bold\*".
113 Swim has a document model that views things as blocks and phrases. This
115 is very similar to HTML's DIV and SPAN concepts. Swim views a document
116 as a sequence of top level blocks. Blocks are further subdivided into
117 either a sequence of blocks or a sequence of phrases. Phrases can only
118 be subdivided into more phrases.
119 Consider this example document:
121 A paragraph *is* a block. It gets divided into phrases like 'pure text' and
123 *bold text*. A bold phrase can be divided: *all bold /some italic/*.
124 * Lists are blocks.
126 * Each item is a block.
127 * A sublist is a block.
128 * The text within in contains *phrases*.
129 Common blocks and phrases have an implicit (DWIM) syntax, that reads
131 very natural. For instance a paragraph is just left justified text that
132 is terminated by a blank line. There is also an explicit syntax for
133 blocks and phrases. Every implicit syntax can be written explicitly.
134 For instance, here is an implicit syntax example followed by its
135 explicit equivalent:
136 A paragraph with some *bold text* in it.
138 <<< para
140 A paragraph with some <bold bold text> in it.
141 >>>
142 Two Space Indent
144 Swim uses a 2 space indentation and it is very instrumental to its
146 design. It allows for a very nice and natural embedding of blocks
147 within blocks. Consider this list:
148 * Point one has
150 text on 2 lines
151 * Subpoint a
152 * Point two
153 A paragraph for point 2 followed by some preformatted text:
155 # Code example
156 * Point three
157 As you can see, 2 space indent is very natural here and allows for
159 putting blocks inside blocks in a way that is not available in most
160 markups.
161 Swim Syntax
163 There are 4 sets of syntax to define: block/implicit, phrase/implicit,
164 block/explicit and phrase/explicit. There are also escaping mechanisms.
165 Block/Implicit Syntaxes
167 A paragraph is a contiguous set of plain text lines. It is terminated
169 by a blank line or by another block syntax at that level.
170 To be continued
172 <<<cpan-tail>>>
174perl v5.36.0 2022-07-22 Swim(3)