basis-library/util/natural.sml

   1 (* Copyright (C) 1999-2006 Henry Cejtin, Matthew Fluet, Suresh
   2  *    Jagannathan, and Stephen Weeks.
   3  * Copyright (C) 1997-2000 NEC Research Institute.
   4  *
   5  * MLton is released under a BSD-style license.
   6  * See the file MLton-LICENSE for details.
   7  *)
   8
   9 structure Natural =
  10    struct
  11       fun foldStartStop (start, stop, b, f) =
  12          if start > stop
  13             then raise Subscript
  14          else
  15             let
  16                fun loop (i, b) =
  17                   if i >= stop then b
  18                   else loop (i + 1, f (i, b))
  19             in loop (start, b)
  20             end
  21
  22       fun foreachStartStop (start, stop, f) =
  23          foldStartStop (start, stop, (), fn (i, ()) => f i)
  24
  25       fun foreach (n, f) = foreachStartStop (0, n, f)
  26    end