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diff --git a/narrative.md b/narrative.md deleted file mode 100644 index 7390662..0000000 --- a/narrative.md +++ /dev/null @@ -1,140 +0,0 @@ ---- -title: CommonMark -... - -CommonMark is a [specification of Markdown -syntax](http://jgm.github.io/stmd/spec.html), together with -BSD3-licensed implementations in C and JavaScript. The source -for the spec and the two implementations can be found in [this -repository](http://github.com/jgm/stmd). - -The C implementation provides both a library and a standalone program -`cmark` that converts Markdown to HTML. It is written in standard C99 -and has no library dependencies. - -The JavaScript implementation is a single JavaScript file, with no -dependencies. [Try it now!](http://jgm.github.io/stmd/js/) - -[The spec](http://jgm.github.io/stmd/spec.html) contains over 400 -embedded examples which serve as conformance tests. (The source contains -a perl script that will run the tests against any Markdown program.) - -The spec is written from the point of view of the human writer, not the -computer reader. It is not an algorithm—an English translation of a -computer program—but a declarative description of what counts as a block -quote, a code block, and each of the other structural elements that can -make up a Markdown document. For the most part, the spec limits itself -to the basic elements described in John Gruber’s [canonical syntax -description](http://daringfireball.net/projects/markdown/syntax), -eschewing extensions like footnotes and definition lists. It is -important to get the core right before considering such things. - -Because Gruber’s syntax description leaves many aspects of the syntax -undetermined, writing a precise spec requires making a large number of -decisions, many of them somewhat arbitrary. In making them, I have -appealed to existing conventions and considerations of simplicity, -readability, expressive power, and consistency. I have tried to ensure -that “normal” documents in the many incompatible existing -implementations of Markdown will render, as far as possible, as their -authors intended. And I have tried to make the rules for different -elements work together harmoniously. In places where different decisions -could have been made (for example, the rules governing list -indentation), I have explained the rationale for my choices. In a few -cases, I have departed slightly from the canonical syntax description, -in ways that I think further the goals of Markdown as stated in that -description. - -There are only a few places where this spec says things that contradict -the canonical syntax description: - -- It [allows all punctuation symbols to be - backslash-escaped](http://jgm.github.io/stmd/spec.html#backslash-escapes), - not just the symbols with special meanings in Markdown. I found - that it was just too hard to remember which symbols could be - escaped. - -- It introduces an [alternative syntax for hard line - breaks](http://jgm.github.io/stmd/spec.html#hard-line-breaks), a - backslash at the end of the line, supplementing the - two-spaces-at-the-end-of-line rule. This is motivated by persistent - complaints about the “invisible” nature of the two-space rule. - -- Link syntax has been made a bit more predictable (in a - backwards-compatible way). For example, `Markdown.pl` allows single - quotes around a title in inline links, but not in reference links. - This kind of difference is really hard for users to remember, so the - spec [allows single quotes in both - contexts](http://jgm.github.io/stmd/spec.html#links). - -- The rule for HTML blocks differs, though in most real cases it - shouldn't make a difference. (See - [here](http://jgm.github.io/stmd/spec.html#html-blocks) for - details.) The spec's proposal makes it easy to include Markdown - inside HTML block-level tags, if you want to, but also allows you to - exclude this. It is also makes parsing much easier, avoiding - expensive backtracking. - -- It does not collapse adjacent bird-track blocks into a single - blockquote: - - > this is two - - > blockquotes - - > this is a single - > - > blockquote with two paragraphs - -- Rules for content in lists differ in a few respects, though (as with - HTML blocks), most lists in existing documents should render as - intended. There is some discussion of the choice points and - differences [here](http://jgm.github.io/stmd/spec.html#motivation). - I think that the spec's proposal does better than any existing - implementation in rendering lists the way a human writer or reader - would intuitively understand them. (I could give numerous examples - of perfectly natural looking lists that nearly every existing - implementation flubs up.) - -- The spec stipulates that two blank lines break out of all list - contexts. This is an attempt to deal with issues that often come up - when someone wants to have two adjacent lists, or a list followed by - an indented code block. - -- Changing bullet characters, or changing from bullets to numbers or - vice versa, starts a new list. I think that is almost always going - to be the writer's intent. - -- The number that begins an ordered list item may be followed by - either `.` or `)`. Changing the delimiter style starts a new - list. - -- The start number of an ordered list is significant. - -- [Fenced code blocks](http://jgm.github.io/stmd/spec.html#fenced-code-blocks) are supported, delimited by either - backticks (` ``` `) or tildes (` ~~~ `). - -In all of this, I have been guided by eight years experience writing -Markdown implementations in several languages, including the first -Markdown parser not based on regular expression substitutions -([pandoc](http://github.com/jgm/pandoc)) and the first Markdown parsers -based on PEG grammars -([peg-markdown](http://github.com/jgm/peg-markdown), -[lunamark](http://github.com/jgm/lunamark)). Maintaining these projects -and responding to years of user feedback have given me a good sense of -the complexities involved in parsing Markdown, and of the various design -decisions that can be made. I have also explored differences between -Markdown implementations extensively using [babelmark -2](http://johnmacfarlane.net/babelmark2/). In the early phases of -working out the spec, I benefited greatly from collaboration with David -Greenspan, and from extensive discussions with a group of industrial -users of Markdown, including Jeff Atwood, Vincent Marti, and Neil -Williams. - -### Contributing - -There is a [forum for discussing -CommonMark](http://talk.commonmark.org); you should use it instead of -github issues for questions and possibly open-ended discussions. -Use the [github issue tracker](http://github.com/jgm/stmd/issues) -only for simple, clear, actionable issues. - |