raise (UnificationFailure (sprintf
"Error trying to unify %s with %s: the algorithm tried to check whether the two substitutions are convertible; if they are not, it tried to unify the two substitutions. No restriction was attempted."
(CicMetaSubst.ppterm subst t1) (CicMetaSubst.ppterm subst t2)))
- | (C.Meta (n,l), C.Meta (m,_)) when n>m ->
+ | (C.Meta (n,_), C.Meta (m,_)) when n>m ->
fo_unif_subst subst context metasenv t2 t1
| (C.Meta (n,l), t)
| (t, C.Meta (n,l)) ->
+ let swap =
+ match t1,t2 with
+ C.Meta (n,_), C.Meta (m,_) when n < m -> false
+ | _, C.Meta _ -> false
+ | _,_ -> true
+ in
+ let lower = fun x y -> if swap then y else x in
+ let upper = fun x y -> if swap then x else y in
+ let fo_unif_subst_ordered subst context metasenv m1 m2 =
+ fo_unif_subst subst context metasenv (lower m1 m2) (upper m1 m2)
+ in
let subst'',metasenv' =
try
let oldt = (List.assoc n subst) in
let lifted_oldt = S.lift_meta l oldt in
- fo_unif_subst subst context metasenv lifted_oldt t
+ fo_unif_subst_ordered subst context metasenv t lifted_oldt
with Not_found ->
let t',metasenv',subst' =
try
(CicMetaSubst.MetaSubstFailure msg)-> raise(UnificationFailure msg)
| (CicMetaSubst.Uncertain msg) -> raise (Uncertain msg)
in
- (n, t')::subst', metasenv'
+ (n, t')::subst', metasenv'
in
let (_,_,meta_type) = CicUtil.lookup_meta n metasenv' in
(try
let tyt =
type_of_aux' metasenv' subst'' context t
in
- fo_unif_subst subst'' context metasenv' (S.lift_meta l meta_type) tyt
+ fo_unif_subst subst'' context metasenv' tyt (S.lift_meta l meta_type)
with AssertFailure _ ->
(* TODO huge hack!!!!
* we keep on unifying/refining in the hope that the problem will be