Markdown Extra Spec: Parsing Section

John MacFarlane jgm at
Fri May 16 01:37:19 EDT 2008

> And I was under the impression that you had given me a nearly complete

> cheatsheet of the PEG grammar in that previous email. What does $, ->>,

> <++>, and ## mean?

Sorry, these are not standard PEG symbols, but they are used in the
Haskell PEG library I'm using (Frisby). If you look at the source code
of Markdown.hs, you'll find a table correlating Frisby notation with
standard PEG notation:

The only symbol not explained there is '$'. '$' is a standard Haskell sign
for function application; basically it's just a way to write things with
fewer parentheses. So, for example,

newRule $ blah blah blah

is the same as

newRule (blah blah blah)


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