src/Pure/Thy/bibtex.scala

     def is_open: Boolean =
       kind == Token.Kind.KEYWORD && (source == "{" || source == "(")
   }
 
   case class Chunk(kind: String, tokens: List[Token]) {
-    val source = tokens.map(_.source).mkString
+    val source: String = tokens.map(_.source).mkString
 
     private val content: Option[List[Token]] =
       tokens match {
         case Token(Token.Kind.KEYWORD, "@") :: body if body.nonEmpty =>
           (body.init.filterNot(_.is_ignored), body.last) match {

   case class Item_Start(kind: String) extends Line_Context
   case class Item_Open(kind: String, end: String) extends Line_Context
   case class Item(kind: String, end: String, delim: Delimited) extends Line_Context
 
   case class Delimited(quoted: Boolean, depth: Int)
-  val Closed = Delimited(false, 0)
+  val Closed: Delimited = Delimited(false, 0)
 
   private def token(kind: Token.Kind.Value)(source: String): Token = Token(kind, source)
   private def keyword(source: String): Token = Token(Token.Kind.KEYWORD, source)
 
 

     private def delimited_depth(delim: Delimited): Parser[(String, Delimited)] =
       new Parser[(String, Delimited)] {
         require(if (delim.quoted) delim.depth > 0 else delim.depth >= 0,
           "bad delimiter depth")
 
-        def apply(in: Input) = {
+        def apply(in: Input): ParseResult[(String, Delimited)] = {
           val start = in.offset
           val end = in.source.length
 
           var i = start
           var q = delim.quoted

     private val identifier =
       """[\x21-\x7f&&[^"#%'(),={}0-9]][\x21-\x7f&&[^"#%'(),={}]]*""".r
 
     private val ident = identifier ^^ token(Token.Kind.IDENT)
 
-    val other_token = "[=#,]".r ^^ keyword | (nat | (ident | space))
+    val other_token: Parser[Token] = "[=#,]".r ^^ keyword | (nat | (ident | space))
 
 
     /* body */
 
     private val body =