Pod6 is an easy-to-use markup language. It can be used for writing language documentation, for documenting programs and modules, as well as for other types of document composition.

Every Pod6 document has to begin with =begin pod and end with =end pod. Everything between these two delimiters will be processed and used to generate documentation.

=begin pod
 
A very simple Pod6 document
 
=end pod

Block structure§

A Pod6 document may consist of multiple Pod6 blocks. There are four ways to define a block: delimited, paragraph, abbreviated, and declarator; the first three yield the same result but the fourth differs. You can use whichever form is most convenient for your particular documentation task.

Delimited blocks§

Delimited blocks are bounded by =begin and =end markers, both of which are followed by a valid Raku identifier, which is the typename of the block. Typenames that are entirely lowercase (for example: =begin head1) or entirely uppercase (for example: =begin SYNOPSIS) are reserved. Indentation of the =begin/=end lines is required to be the same to create a valid block; otherwise, an error or unexpected results will occur.

=begin head1
Top Level Heading
=end head1

Configuration information§

After the typename, the rest of the =begin marker line is treated as configuration information for the block. This information is used in different ways by different types of blocks, but is always specified using Raku-ish option pairs. That is, any of:

Where '$e1, $e2, ...' are list elements of type String, Int, Number, or Boolean. Lists may have mixed element types. Note that one-element lists are converted to the type of their element (String, Int, Number, or Boolean). Also note that big integers can be used if required.

For hashes, '$k1, $k2, ...' are keys of type Str and '$v1, $v2, ...' are values of type String, Int, Number, or Boolean.

Strings are delimited by single or double quotes. Whitespace is not significant outside of strings. Hash keys need not be quote-delimited unless they contain significant whitespace. Strings entered inside angle brackets become lists if any whitespace is used inside the angle brackets.

All option keys and values must be constants since Pod6 is a specification language, not a programming language. Specifically, option values cannot be closures. See Synopsis 2 for details of the various Raku pair notations.

The configuration section may be extended over subsequent lines. Each subsequent line must start with an = in the first virtual column, meaning that it must vertically align with the = of the Pod6 Block declaration, and it must be followed by at least one horizontal whitespace character.

For example:

     =for head1 :a-first-line-key<firstvalue> :another-first-line-key<xyz>
     =          :a-second-line-key(42)
     = :a-third-line-key<third>
     Content for the header block

Some of these options have a predetermined value; specifically, :numbered is used to specify that the block item or lines will be numbered.

=for defn :numbered
               We
               Need
               Numbers
 
say $=pod[0].config<numbered>; # OUTPUT: «True␤» 

This configuration option can be abbreviated by a hash mark

=para #
We
Need
Numbers
 
say $=pod[0].config<numbered>; # OUTPUT: «1␤» 

Paragraph blocks§

Paragraph blocks begin by a =for marker and end by the next Pod6 directive or the first blank line. The =for marker is followed by the typename of the block plus, optionally, any configuration data as in the delimited blocks described above.

=for head1
Top Level Heading

Abbreviated blocks§

Abbreviated blocks begin with an = sign, which is followed immediately by the typename of the block. All following data are part of the contents of the block, thus configuration data cannot be specified for an abbreviated block. The block ends at the next Pod6 directive or the first blank line.

=head1 Top level heading 

Declarator blocks§

Declarator blocks differ from the others by not having a specific type, instead they are attached to some source code.

Declarator blocks are introduced by a special comment: either #| or #=, which must be immediately followed by either a space or an opening curly brace. If followed by a space, the block is terminated by the end of line; if followed by one or more opening curly braces, the block is terminated by the matching sequence of closing curly braces.

Blocks starting with #| are attached to the code after them, and blocks starting with #= are attached to the code before them.

Since declarator blocks are attached to source code, they can be used to document classes, roles, subroutines and in general any statement or block.

The WHY method can be used on these classes, roles, subroutines etc. to return the attached Pod6 value.

#| Base class for magicians 
class Magician {
  has Int $.level;
  has Str @.spells;
}
 
#| Fight mechanics 
sub duel(Magician $a, Magician $b) {
}
#= Magicians only, no mortals. 
 
say Magician.WHY; # OUTPUT: «Base class for magicians␤» 
say &duel.WHY.leading; # OUTPUT: «Fight mechanics␤» 
say &duel.WHY.trailing; # OUTPUT: «Magicians only, no mortals.␤» 

These declarations can extend multiple blocks:

#|( This is an example of stringification: 
    * Numbers turn into strings
    * Regexes operate on said strings
    * C<with> topicalizes and places result into $_
)
sub search-in-seq( Int $end, Int $number ) {
    with (^$end).grep( /^$number/ ) {
        .say for $_<>;
    }
}
#=« Uses 
    * topic
    * decont operator
»

By using a matched pair of parenthesis constructs such as () or «» the comments can extend multiple lines. This format will not normally translate to a multi-line display by raku --doc. However, since Rakudo version 2020.01, there is a method to accomplish that, for leading declarator blocks only, by defining a special environment variable: RAKUDO_POD_DECL_BLOCK_USER_FORMAT. When that value is set, running raku with the --doc option should show text from leading declarator blocks in its original format. See the test for the capability in the file S26-documentation/block-leading-user-format.t.

Block types§

Pod6 offers a wide range of standard block types.

Headings§

Headings can be defined using =headN, where N is greater than zero (e.g., =head1, =head2, …).

=head1 A top level heading 
 
=head2 A second level heading 
 
=head3 A third level heading 

Ordinary paragraphs§

An ordinary paragraph consists of text that is to be formatted into a document at the current level of nesting, with whitespace squeezed, lines filled, and any special inline mark-up applied.

Ordinary paragraphs consist of one or more consecutive lines of text, each of which starts with a non-whitespace character. The paragraph is terminated by the first blank line or block directive.

For example:

=head1 This is a heading block 
 
This is an ordinary paragraph.
Its text  will   be     squeezed     and
short lines filled. It is terminated by
the first blank line.
 
This is another ordinary paragraph.
Its     text    will  also be squeezed and
short lines filled. It is terminated by
the trailing directive on the next line.
 
=head2 This is another heading block 
 
This is yet another ordinary paragraph,
at the first virtual column set by the
previous directive

Ordinary paragraphs do not require an explicit marker or delimiters.

Alternatively, there is also an explicit =para marker that can be used to explicitly mark a paragraph.

=para
This is an ordinary paragraph.
Its text  will   be     squeezed     and
short lines filled.

In addition, the longer =begin para and =end para form can be used.

For example:

=begin para
This is an ordinary paragraph.
Its text  will   be     squeezed     and
short lines filled.
 
This is still part of the same paragraph,
which continues until an...
=end para

As demonstrated by the previous example, within a delimited =begin para and =end para block, any blank lines are preserved.

Code blocks§

Code blocks are used to specify source code, which should be rendered without re-justification, without whitespace-squeezing, and without recognizing any inline formatting codes. Typically these blocks are used to show examples of code, mark-up, or other textual specifications, and are rendered using a fixed-width font.

A code block may be implicitly specified as one or more lines of text, each of which starts with a whitespace character. The implicit code block is then terminated by a blank line.

For example:

This ordinary paragraph introduces a code block:
 
    my $name = 'John Doe';
    say $name;

Code blocks can also be explicitly defined by enclosing them in =begin code and =end code

    =begin code
    my $name = 'John Doe';
    say $name;
    =end code

I/O blocks§

Pod6 provides blocks for specifying the input and output of programs.

The =input block is used to specify pre-formatted keyboard input, which should be rendered without re-justification or squeezing of whitespace.

The =output block is used to specify pre-formatted terminal or file output, which should also be rendered without re-justification or whitespace-squeezing.

Lists§

Unordered lists§

Lists in Pod6 are specified as a series of =item blocks.

For example:

The three suspects are:
 
=item  Happy 
=item  Sleepy 
=item  Grumpy 

The three suspects are:

• Happy

• Sleepy

• Grumpy

Definition lists§

Lists that define terms or commands use =defn, equivalent to the DL lists in HTML

=defn Happy 
When you're not blue.
 
=defn Blue 
When you're not happy.

will be rendered as

Happy

When you're not blue.

Blue

When you're not happy.

Multi-level lists§

Lists may be multi-level, with items at each level specified using the =item1, =item2, =item3, etc. blocks.

Note that =item is just an abbreviation for =item1.

For example:

=item1  Animal 
=item2     Vertebrate 
=item2     Invertebrate 
 
=item1  Phase 
=item2     Solid 
=item2     Liquid 
=item2     Gas 

• Animal

• Vertebrate

• Invertebrate

• Phase

• Solid

• Liquid

• Gas

Multi-paragraph lists§

Using the delimited form of the =item block (=begin item and =end item), we can specify items that contain multiple paragraphs.

For example:

Let's consider two common proverbs:
 
=begin item
I<The rain in Spain falls mainly on the plain.>
 
This is a common myth and an unconscionable slur on the Spanish
people, the majority of whom are extremely attractive.
=end item
 
=begin item
I<The early bird gets the worm.>
 
In deciding whether to become an early riser, it is worth
considering whether you would actually enjoy annelids
for breakfast.
=end item
 
As you can see, folk wisdom is often of dubious value.

Renders as:

Let's consider two common proverbs:

• The rain in Spain falls mainly on the plain.

  This is a common myth and an unconscionable slur on the Spanish people, the majority of whom are extremely attractive.

• The early bird gets the worm.

  In deciding whether to become an early riser, it is worth considering whether you would actually enjoy annelids for breakfast.

As you can see, folk wisdom is often of dubious value.

Tables§

Check out this page for documentation related to Tables

Pod6 comments§

Pod6 comments are comments that Pod6 renderers ignore.

Comments are useful for metadocumentation (documenting the documentation). Single-line comments use the =comment marker:

=comment Add more here about the algorithm 

For multi-line comments, use a delimited comment block:

=begin comment
This comment is
multi-line.
=end comment

You can also use implicit block:

=comment
This comment is
multi-line.
 
B<this> is visible

Semantic blocks§

All uppercase block typenames are reserved for specifying standard documentation, publishing, source components, or meta-information.

=NAME
=AUTHOR
=VERSION
=TITLE
=SUBTITLE

Formatting codes§

Formatting codes provide a way to add inline mark-up to a piece of text.

All Pod6 formatting codes consist of a single capital letter followed immediately by a set of single or double angle brackets; Unicode double angle brackets may be used.

Formatting codes may nest other formatting codes.

The following codes are available: B, C, E, I, K, L, N, P, R, T, U, V, X, and Z.

Bold§

To format a text in bold enclose it in B< >

Raku is B<awesome>

Raku is awesome

Italic§

To format a text in italic enclose it in I< >

Raku is I<awesome>

Raku is awesome

Underlined§

To underline a text enclose it in U< >

Raku is U<awesome>

Code§

To flag text as code and treat it verbatim enclose it in C< >

C<my $var = 1; say $var;>

my $var = 1; say $var;

Links§

To create a link enclose it in L< >:

Raku homepage L<https://raku.org>

Raku homepage https://raku.org

An optional vertical bar can be used to separate the label from the target.

L<Raku homepage|https://raku.org>

Raku homepage

Relative URLs are relative to the base of the project, so in this repository, for example, we can link to another page in the language folder. Here we use an optional fragment to link to a heading:

L<Structure|/language/about#Structure>

Structure

One can also specify a link to a fragment in the current document:

L<Comments|#Comments>

Comments

Finally, in addition to URL-style links (e.g. L<Some reference|path/to/filename>), module-style notation (L<Some reference|path::to::filename>) also works.

Placement links§

This code is not implemented in Pod::To::HTML, but is partially implemented in Pod::To::BigPage.

A second kind of link — the P<> or placement link — works in the opposite direction. Instead of directing focus out to another document, it allows you to assimilate the contents of another document into your own.

In other words, the P<> formatting code takes a URI and (where possible) inserts the contents of the corresponding document inline in place of the code itself.

P<> codes are handy for breaking out standard elements of your documentation set into reusable components that can then be incorporated directly into multiple documents. For example:

=COPYRIGHT
P<file:/shared/docs/std_copyright.pod>
 
=DISCLAIMER
P<http://www.MegaGigaTeraPetaCorp.com/std/disclaimer.txt>

might produce:

If a renderer cannot find or access the external data source for a placement link, it must issue a warning and render the URI directly in some form, possibly as an outwards link. For example:

You can use any of the following URI forms (see Links) in a placement link.

Comments§

A comment is text that is never rendered.

To create a comment enclose it in Z< >

Raku is awesome Z<Of course it is!>

Raku is awesome

Notes§

Notes are rendered as footnotes.

To create a note enclose it in N< >

Raku is multi-paradigmatic N<Supporting Procedural, Object Oriented, and Functional programming>

Keyboard input§

To flag text as keyboard input enclose it in K< >

Enter your name K<John Doe>

Replaceable§

The R<> formatting code specifies that the contained text is a replaceable item, a placeholder, or a metasyntactic variable. It is used to indicate a component of a syntax or specification that should eventually be replaced by an actual value. For example:

The basic C<ln> command is: C<ln> R<source_file> R<target_file>

or:

Then enter your details at the prompt:
 
=for input
    Name: R<your surname>
      ID: R<your employee number>
    Pass: R<your 36-letter password>

Terminal output§

To flag text as terminal output enclose it in T< >

Hello T<John Doe>

Unicode§

To include Unicode code points or HTML5 character references in a Pod6 document, enclose them in E< >

E< > can enclose a number, which is treated as the decimal Unicode value for the desired code point. It can also enclose explicit binary, octal, decimal, or hexadecimal numbers using the Raku notations for explicitly based numbers.

It can also enclose a Unicode code point name.

Raku makes considerable use of the E<laquo> and E<raquo> characters.
 
Raku makes considerable use of the E<171> and E<187> characters.
 
Raku makes considerable use of the E<0b10101011> and E<0b10111011> characters.
 
Raku makes considerable use of the E<0o253> and E<0o273> characters.
 
Raku makes considerable use of the E<0d171> and E<0d187> characters.
 
Raku makes considerable use of the E<0xAB> and E<0xBB> characters.
 
Raku makes considerable use of the E<LEFT-POINTING DOUBLE ANGLE QUOTATION MARK> and E<RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK> characters.

Raku makes considerable use of the « and » characters.

You can also provide multiple code points in a ; separated list, such as:

Raku makes considerable use of E<171;nbsp;raquo>.

Raku makes considerable use of « ».

Verbatim text§

This code is not implemented by Pod::To::HTML, but is implemented in Pod::To::BigPage.

The V<> formatting code treats its entire contents as being verbatim, disregarding every apparent formatting code within it. For example:

The B<V<V<>>> formatting code disarms other codes
such as V<I<>, C<>, B<>, and M<>.>

Note, however that the V<> code only changes the way its contents are parsed, not the way they are rendered. That is, the contents are still wrapped and formatted like plain text, and the effects of any formatting codes surrounding the V<> code are still applied to its contents. For example the previous example is rendered as:

Indexing terms§

Anything enclosed in an X<> code is an index entry. The contents of the code are both formatted into the document and used as the (case-insensitive) index entry:

An X<array> is an ordered list of scalars indexed by number,
starting with 0. A X<hash> is an unordered collection of scalar
values indexed by their associated string key.

You can specify an index entry in which the indexed text and the index entry are different, by separating the two with a vertical bar:

An X<array|arrays> is an ordered list of scalars indexed by number,
starting with 0. A X<hash|hashes> is an unordered collection of
scalar values indexed by their associated string key.

In the two-part form, the index entry comes after the bar and is case-sensitive.

You can specify hierarchical index entries by separating indexing levels with commas:

An X<array|arrays, definition of> is an ordered list of scalars
indexed by number, starting with 0. A X<hash|hashes, definition of>
is an unordered collection of scalar values indexed by their
associated string key.

You can specify two or more entries for a single indexed text, by separating the entries with semicolons:

A X<hash|hashes, definition of; associative arrays>
is an unordered collection of scalar values indexed by their
associated string key.

The indexed text can be empty, creating a "zero-width" index entry:

X<|puns, deliberate>This is called the "Orcish Maneuver"
because you "OR" the "cache".

Rendering Pod§

HTML§

In order to generate HTML from Pod, you need the Pod::To::HTML module.

If it is not already installed, install it by running the following command: zef install Pod::To::HTML

Once installed, run the following command in the terminal:

raku --doc=HTML input.rakudoc > output.html

Markdown§

In order to generate Markdown from Pod, you need the Pod::To::Markdown module.

If it is not already installed, install it by running the following command: zef install Pod::To::Markdown

Once installed, run the following command in the terminal:

raku --doc=Markdown input.rakudoc > output.md

Text§

In order to generate text from Pod, you can use the default Pod::To::Text module.

Using the terminal, run the following command:

raku --doc=Text input.rakudoc > output.txt

You can omit the =Text portion:

raku --doc input.rakudoc > output.txt

You can even embed Pod6 directly in your program and add the traditional Unix command line "--man" option to your program with a multi MAIN subroutine like this:

multi MAIN(Bool :$man) {
    run $*EXECUTABLE, '--doc', $*PROGRAM;
}

Now myprogram --man will output your Pod6 rendered as a man page.

Accessing Pod§

In order to access Pod6 documentation from within a Raku program the special = twigil, as documented in the variables section, must be used.

The = twigil provides the introspection over the Pod6 structure, providing a Pod::Block tree root from which it is possible to access the whole structure of the Pod6 document.

As an example, the following piece of code introspects its own Pod6 documentation:

=begin pod
 
=head1 This is a head1 title 
 
This is a paragraph.
 
=head2 Subsection 
 
Here some text for the subsection.
 
=end pod
 
for $=pod -> $pod-item {
    for $pod-item.contents -> $pod-block {
      $pod-block.raku.say;
    }
}

producing the following output:

Pod::Heading.new(level => 1, config => {}, contents => [Pod::Block::Para.new(config => {}, contents => ["This is a head1 title"])]);
Pod::Block::Para.new(config => {}, contents => ["This is a paragraph."]);
Pod::Heading.new(level => 2, config => {}, contents => [Pod::Block::Para.new(config => {}, contents => ["Subsection"])]);
Pod::Block::Para.new(config => {}, contents => ["Here some text for the subsection."]);