Line comments misidentified

[tfausak]

Line comments in Haskell are complicated. They're made up of at least two hyphens in a row. Sounds easy enough. But they can't form a valid lexeme. In other words, --- is a comment, but <--- and ---> aren't. Purple Yolk doesn't currently handle this correctly:

I'm curious to see how GitHub's syntax highlighter handles this:

are these comments?
--    yes
--|   no
|--   no
---   yes
---|  shouldn't be
|---  shouldn't be

[tfausak]

Oops, I meant to link the report: https://www.haskell.org/onlinereport/haskell2010/haskellch2.html#x7-170002.3

An ordinary comment begins with a sequence of two or more consecutive dashes (e.g. --) and extends to the following newline. The sequence of dashes must not form part of a legal lexeme. For example, “-->” or “|--” do not begin a comment, because both of these are legal lexemes; however “--foo” does start a comment.

[tfausak]

https://github.com/tfausak/purple-yolk/blob/3041fe83de5f63e2e2a37fb4e792e332cbc3ad6e/grammars/haskell-grammar.json#L56-L59