src/Pure/General/lazy_seq.ML

 exception Empty
 
 fun getItem (Seq s) = force s
 fun make f = Seq (delay f)
 
-fun null s = is_some (getItem s)
+fun null s = isSome (getItem s)
 
 local
     fun F n NONE = n
       | F n (SOME(_,s)) = F (n+1) (getItem s)
 in

 	      | SOME(x,xs) => SOME(x,make (fn () => copy xs))
     in
 	make (fn () => copy (f x))
     end
 
-fun EVERY fs = foldr THEN (fs, succeed)
-fun FIRST fs = foldr ORELSE (fs, fail)
+fun EVERY fs = Library.foldr THEN (fs, succeed)
+fun FIRST fs = Library.foldr ORELSE (fs, fail)
 
 fun TRY f x =
     make (fn () =>
 	     case getItem (f x) of
 		 NONE => SOME(x,Seq (value NONE))