--- a/src/Pure/RAW/single_assignment.ML Wed Feb 17 21:51:58 2016 +0100
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,33 +0,0 @@
-(* Title: Pure/RAW/single_assignment.ML
- Author: Makarius
-
-References with single assignment. Unsynchronized!
-*)
-
-signature SINGLE_ASSIGNMENT =
-sig
- type 'a saref
- exception Locked
- val saref: unit -> 'a saref
- val savalue: 'a saref -> 'a option
- val saset: 'a saref * 'a -> unit
-end;
-
-structure SingleAssignment: SINGLE_ASSIGNMENT =
-struct
-
-exception Locked;
-
-abstype 'a saref = SARef of 'a option ref
-with
-
-fun saref () = SARef (ref NONE);
-
-fun savalue (SARef r) = ! r;
-
-fun saset (SARef (r as ref NONE), x) = r := SOME x
- | saset _ = raise Locked;
-
-end;
-
-end;