From: Enrico Tassi <enrico.tassi@inria.fr>
Date: Thu, 30 Aug 2007 16:24:31 +0000 (+0000)
Subject: bugfix in computation of src and tgt for coercions with arity > 0
X-Git-Tag: 0.4.95@7852~237
X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=commitdiff_plain;h=2b867cf85544ca5464b261910cc15d3a3a0aefe5;p=helm.git

bugfix in computation of src and tgt for coercions with arity > 0
---

diff --git a/components/library/librarySync.ml b/components/library/librarySync.ml
index cbc45e6a9..5897d62ba 100644
--- a/components/library/librarySync.ml
+++ b/components/library/librarySync.ml
@@ -259,18 +259,19 @@ let add_coercion ~add_composites refinement_toolkit uri arity saturations
   in
   let src_carr, tgt_carr = 
     let get_classes arity saturations l = 
-      let rec aux target = function
-         0,0,tgt::src::_ when target = None -> src,Some (`Class tgt)
-       | 0,0,src::_ when target <> None -> src,target
-       | 0,saturations,tgt::tl when target = None ->
-          aux (Some (`Class tgt)) (0,saturations,tl)
-       | 0,saturations,_::tl ->
-          aux target (0,saturations - 1,tl)
-       | arity,saturations,_::tl ->
-          aux (Some `Funclass) (arity - 1, saturations, tl)
-       | _,_,_ -> assert false
+      (* this is the ackerman's function revisited *)
+      let rec aux = function
+         0,0,None,tgt::src::_ -> src,Some (`Class tgt)
+       | 0,0,target,src::_ -> src,target
+       | 0,saturations,None,tgt::tl -> aux (0,saturations,Some (`Class tgt),tl)
+       | 0,saturations,target,_::tl -> aux (0,saturations - 1,target,tl)
+       | arity,saturations,None,_::tl -> 
+            aux (arity, saturations, Some `Funclass, tl)
+       | arity,saturations,target,_::tl -> 
+            aux (arity - 1, saturations, target, tl)
+       | _ -> assert false
       in
-       aux None (arity,saturations,List.rev l)
+       aux (arity,saturations,None,List.rev l)
     in
     let types = spine2list coer_ty in
     let src,tgt = get_classes arity saturations types in