YAMD

Indentation-based markup language that compiles to HTML via Ruby codegen.

Syntax

Structure is defined by indentation (tabs). Lines at a given indent level belong to the enclosing directive.

Directives (line-start only)

Syntax	Description
#% <ruby code>	Metadata / Ruby statement. e.g. #% meta "date", "2025 01 01"
#! <expr>	Block wrapper. Evaluates expr as a Ruby method call, content is passed as a block. e.g. #! tag('h1')
#$ <expr>	Raw block. Like #! but inner lines are passed as a raw string (no YAMD parsing). Used for code blocks. e.g. #$ code
#.	List item. Must appear inside a #! list(...) block

Inline constructs

Syntax	Description
#`...`	Inline code
#{expr}	Ruby expression interpolation (result converted to string)
#(expr)	Inline math (AsciiMath, rendered to MathML)
#name(args)	Method call. e.g. #link("url")
#name(args)#{ content }#	Method call with content block. e.g. #link("url")#{ click here }#
##	Escaped literal #
}#	Closes a #{ content block

Comments

Lines matching # followed by nothing or a space (i.e. # or # ...) are comments and are skipped.

Available renderer methods

These are defined by HTMLRenderer in exe/yamd:

Method	Usage
tag(name, **attrs)	HTML element. #! tag('h2')
list(numbering)	List. numbering: "-" (ul), "1", "a", "A", "i", "I" (ol). Dot-separated for nested: "-.1"
link(url)	Anchor tag. #link("https://example.com")#{ text }#
code(lang: Lang::DEFAULT)	Code block (used via #$). Optional lang: for highlighting rules
meta(name, value)	HTML <meta> tag. Used via #%
inline_code(text)	Inline <code>. Used via #`...`
inline_math(text)	AsciiMath to MathML. Used via #(...)

Example

#% meta "date", "2025 01 01"

#! tag('h1')
	Title

Paragraph text with #`inline code` and #link("https://example.com")#{ a link }#.

#! list('-')
	#. First item
	#. Second item with sub-content
		#$ code
			x = 1