Demo syntax and syntax-markdown extensions #65

[jmatsushita]

And building on #65 here's a demo of the syntax modules (for now pinned to github commits). It would be great if you could take a look at

• https://github.com/iilab/rasa-ext-syntax/commit/20bbd32d703537d86d01f1291bef1a722523e7a2
• https://github.com/iilab/rasa-ext-syntax-markdown/commit/9e326a8ffef5f18c7cf00f1df47d442b8857306d

before I make the jump to submit my first packages on hackage?

The idea is that a syntax extension implements

type Lexer a = Y.YiString -> Tokens a
type Styler a = TokenRange a -> BufAction (Span CrdRange Style)
type Mapper = [Extension]
data Syntax a = Syntax String Mapper (Lexer a) (Styler a)

for instance:

markdown :: Mapper -> Syntax MarkdownToken
markdown mapper = Syntax "Markdown" mapper lexer styler

Which then allows to add extensions like so:

main :: IO ()
main = rasa $ do
  ...
  syntax [markdown [Extension ".md"]]

[ChrisPenner]

I just changed the base branch to be your other feature to clean up the diff while we review it; we'll switch it back to master when we merge 👍