src/Pure/library.ML

   val random: unit -> real
   val random_range: int -> int -> int
   val one_of: 'a list -> 'a
   val frequency: (int * 'a) list -> 'a
 
-  (*current directory*)
-  val cd: string -> unit
-  val pwd: unit -> string
-
   (*misc*)
   val divide_and_conquer: ('a -> 'a list * ('b list -> 'b)) -> 'a -> 'b
   val partition_eq: ('a * 'a -> bool) -> 'a list -> 'a list list
   val partition_list: (int -> 'a -> bool) -> int -> int -> 'a list -> 'a list list
   val gensym: string -> string

       if n <= k then x else pick (n - k) xs
   in pick (random_range 1 sum) xs end;
 
 
 
-(** current directory **)
-
-val cd = OS.FileSys.chDir;
-val pwd = OS.FileSys.getDir;
-
-
-
 (** misc **)
 
 fun divide_and_conquer decomp x =
   let val (ys, recomb) = decomp x
   in recomb (map (divide_and_conquer decomp) ys) end;