feat: expose mini-cc compatible API in Term

src/smt/Mini_cc.ml

@@ -1,9 +1,9 @@
  
 module H = CCHash
 
-type ('f, 't) view = ('f, 't) Mini_cc_intf.view =
+type ('f, 't, 'ts) view = ('f, 't, 'ts) Mini_cc_intf.view =
   | Bool of bool
-  | App of 'f * 't list
+  | App of 'f * 'ts
   | If of 't * 't * 't
 
 type res = Mini_cc_intf.res =
@@ -29,7 +29,7 @@ module Make(A: ARG) = struct
     mutable n_root: node;
   }
 
-  type signature = (fun_, node) view
+  type signature = (fun_, node, node list) view
 
   module Node = struct
     type t = node
@@ -106,8 +106,8 @@ module Make(A: ARG) = struct
 
   let sub_ t k : unit =
     match T.view t with
-    | Bool _ | App (_, []) -> ()
-    | App (_, l) -> List.iter k l
+    | Bool _ -> ()
+    | App (_, args) -> args k
     | If(a,b,c) -> k a; k b; k c
 
   let rec add_t (self:t) (t:term) : node =
@@ -166,8 +166,10 @@ module Make(A: ARG) = struct
         Sig_tbl.add self.sig_tbl s n
     in
     match T.view n.n_t with
-    | Bool _ | App (_, []) -> ()
-    | App (f, l) -> aux @@ App (f, List.map (find_t_ self) l)
+    | Bool _ -> ()
+    | App (f, args) ->
+      let args = args |> Sequence.map (find_t_ self) |> Sequence.to_list in
+      aux @@ App (f, args)
     | If (a,b,c) -> aux @@ If(find_t_ self a, find_t_ self b, find_t_ self c)
 
   (* merge the two classes *)

src/smt/Mini_cc.mli

@@ -1,9 +1,9 @@
 
 (** {1 Mini congruence closure} *)
 
-type ('f, 't) view = ('f, 't) Mini_cc_intf.view =
+type ('f, 't, 'ts) view = ('f, 't, 'ts) Mini_cc_intf.view =
   | Bool of bool
-  | App of 'f * 't list
+  | App of 'f * 'ts
   | If of 't * 't * 't
 
 type res = Mini_cc_intf.res =

src/smt/Mini_cc_intf.ml

@@ -1,9 +1,13 @@
 
-type ('f, 't) view =
+type ('f, 't, 'ts) view =
   | Bool of bool
-  | App of 'f * 't list
+  | App of 'f * 'ts
   | If of 't * 't * 't
 
+(* TODO: also HO app, Eq, Distinct cases?
+   -> then API that just adds boolean terms and does the right thing in case of
+   Eq/Distinct *)
+
 type res =
   | Sat
   | Unsat
@@ -20,8 +24,10 @@ module type ARG = sig
     type t
     val equal : t -> t -> bool
     val hash : t -> int
-    val view : t -> (Fun.t, t) view
     val pp : t Fmt.printer
+
+    (** View the term through the lens of the congruence closure *)
+    val view : t -> (Fun.t, t, t Sequence.t) view
   end
 end
 

src/smt/Term.ml

@@ -86,6 +86,13 @@ let[@inline] is_const t = match view t with
   | App_cst (_, a) -> IArray.is_empty a
   | _ -> false
 
+let cc_view (t:t) =
+  let module C = Mini_cc in
+  match view t with
+  | Bool b -> C.Bool b
+  | App_cst (f,args) -> C.App (f, IArray.to_seq args)
+  | If (a,b,c) -> C.If (a,b,c)
+
 module As_key = struct
     type t = term
     let compare = compare
@@ -113,3 +120,4 @@ let as_cst_undef (t:term): (cst * Ty.Fun.t) option =
   | _ -> None
 
 let pp = Solver_types.pp_term
+

src/smt/Term.mli

@@ -49,6 +49,8 @@ val is_true : t -> bool
 val is_false : t -> bool
 val is_const : t -> bool
 
+val cc_view : t -> (cst,t,t Sequence.t) Mini_cc.view
+
 (* return [Some] iff the term is an undefined constant *)
 val as_cst_undef : t -> (cst * Ty.Fun.t) option