Significant indentation

[robrix]

Defines >>= over parsers, and demonstrates the use of it for parsing structurally significant indentation, in this case a rose tree of list items.

• Documentation for structurally significant indentation parsing.
• Should there be direct conveniences in support of parsing structurally significant indentation?
• Flesh out the tests’ example to parse text for the list items and store that in the tree.
• Add a Playground which parses (some very minimal subset of) Markdown.
• >>- instead of >>= (a la Runes and swiftz)
  • precedence 150

Fixes #42.
Fixes #50.

/cc @jspahrsummers because of the relevance to Carthage/ogdl-swift#1
/cc @mdiep because of the relevance to Markdown parsing

If this isn’t madness, I don’t know what is.

[robrix]

@jspahrsummers Note that the actual parsing is functioning just fine—the remainder of the work to be done on this branch is documentation/explanatory.

We can point Carthage/ogdl-swift#1 at this branch, or we can just define >>=/bind over parsers there, at your preference. There aren’t any other significant contributions on Madness’ side that I know of yet—although maybe I’ll add some conveniences for parsing significant indentation in light of experience doing it.

[jspahrsummers]

Was this going to become >>-, per @gfontenot's tweets?

[robrix]

Yep, note to-do item at top.

[jspahrsummers]

I think I'd prefer to target this branch, just to minimize code duplication.

[robrix]

I think I'd prefer to target this branch, just to minimize code duplication.

👍