| 1 | (* Copyright (C) 1999-2005 Henry Cejtin, Matthew Fluet, Suresh |
| 2 | * Jagannathan, and Stephen Weeks. |
| 3 | * |
| 4 | * MLton is released under a BSD-style license. |
| 5 | * See the file MLton-LICENSE for details. |
| 6 | *) |
| 7 | |
| 8 | structure FixedPoint: FIXED_POINT = |
| 9 | struct |
| 10 | |
| 11 | fun fix{start, step, equals} = |
| 12 | let |
| 13 | fun loop s = |
| 14 | let val s' = step s |
| 15 | in if equals(s, s') |
| 16 | then s |
| 17 | else loop s' |
| 18 | end |
| 19 | in loop start |
| 20 | end |
| 21 | |
| 22 | fun fix' (f: (unit -> unit) -> unit) = |
| 23 | let |
| 24 | fun loop() = |
| 25 | let val changed = ref false |
| 26 | in f(fn () => changed := true); |
| 27 | if !changed |
| 28 | then loop() |
| 29 | else () |
| 30 | end |
| 31 | in loop() |
| 32 | end |
| 33 | |
| 34 | |
| 35 | end |