Comments.

src/DomainParser.purs

@@ -19,14 +19,21 @@ import Parsing (Parser, fail, runParser)
 import Parsing.String.Basic (alphaNum, letter)
 import Parsing.String (char, string, eof)
 
--- From RFC 1035: <domain> ::= <subdomain> | " "
+-- | From RFC 1035: <domain> ::= <subdomain> | " "
+-- |
+-- | Accepting an optional '.' at the end of the subdomain doesn't conform
+-- | to the (prefered) syntax of a domain as described in RFC 1035.
+-- | However, this last '.' character should be acceptable in most applications,
+-- | specially when an "absolute" name (example.com.) has to be differenciated from a "relative" name (www).
+-- |
+-- | PS: both "absolute" and "relative" are from filesystem's terminology,
+-- | but I assume the reader to be more familiar with file-systems than DNS terminology.
 domain :: Parser String String
 domain = PC.try (string " ") <|> sub_eof
 
 sub_eof :: Parser String String
 sub_eof = do
   sub <- subdomain
-  -- TODO: non standard (RFC 1035).
   PC.optional (char '.')
   eof
   if S.length sub > 255