This is not the usual kind of computer science you might have learned in a compiler course, because it's the other way around: you have the text first, and then you write the grammar that fits the text, not the other way around.
grammarString : String grammarString = """ start <- <char+> {action} char <- [a-z] """
This is a string containing a PEG (Parsing Expression Grammar) rule. It defines a simple grammar with two rules: start and char.
`start` expects one or more lowercase letters (specified by `<char+>`) and applies an action `{action}`.
`char` matches a single lowercase letter.
~
See AboutUs Getting Started blog post announcing the open-sourcing of this technology. github 
To get started with Elm PEG Parser, you first need to define a PEG Grammar using the Grammar type.
PEGN: Parsing Expression Grammar Notation site by Robert S. Muhlestein
MainSpec.elm test case code
and Render Them as Anchors [⇒ MiniLatex: a Parser-Renderer for … ⇐ Render Wiki Link]
We intend to 'abuse' the multiComment parser page (Context: Whitespace) to Parse Wiki-Style Links.
DOT FROM lambda-browsing