`a` is a String that always match to these regexp because `ExplicitLink:a` is created by `"{#{l}}[#{s}]"`.

[ioquatix]

          `a` is a String that always match to these regexp because `ExplicitLink:a` is created by `"{#{l}}[#{s}]"`.

Perhaps it could be more simple if ExplicitLink returns structured data

  ExplicitLink =  Label:l "(" @Sp Source:s Spnl Title @Sp ")"
-                 { "{#{l}}[#{s}]" } # returns string, need to parse this string again...
+                 { { label: l, source: s } } # can return hash

(need to change Link = ExplicitLink | ReferenceLink | AutoLink to return a string if ExplicitLink returns hash)

Originally posted by @tompng in #1320 (comment)

[ioquatix]

@tompng as per our discussion, I've pulled this out into a follow-up action.

Let me know if there is anything I can do here to help. It sounds like you have a strong opinion about how to refactor this, so I'm happy to defer to you.