diff --git a/CHANGES.md b/CHANGES.md
index 43ca8902..319a9a29 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -6,9 +6,9 @@ Requires Menhir 20211230 and OCaml 4.08 or above.
   - Change the pipeline completely to make unit relocation unnecessary. Current
     phases are (roughly):
     1. `Ast.program` —[`RecoverStructure`]—> `Ast.Structured.program`
-    2. `Ast.Structured.program` —[`Scope`,`Quotation`,`Macro`]—> `Scoped.program`
+    2. `Ast.Structured.program` —[`Scope`,`Quotation`,`Macro`]—> `Scoped.program` (aka `API.Compile.scoped_program`)
     3. `Scoped.program` —[`Flatten`]—> `Flat.program`
-    4. `Flat.program` —[`Check`]—> `CheckedFlat.program` (aka `compilation_unit`)
+    4. `Flat.program` —[`Check`]—> `CheckedFlat.program` (aka `API.Compile.compilation_unit`)
     5. `CheckedFlat.program` —[`Spill`,`ToDbl`]—> `Assembled.program`
 
     Steps 4 and 5 operate on a base, that is an `Assembled.program` being
diff --git a/elpi_REPL.ml b/elpi_REPL.ml
index 6ffa0da2..47c43ffa 100644
--- a/elpi_REPL.ml
+++ b/elpi_REPL.ml
@@ -69,7 +69,6 @@ let usage =
   "\t-parse-term parses a term from standard input and prints it\n" ^ 
   "\t-print-ast prints files as parsed, then exit\n" ^ 
   "\t-print prints files after most compilation passes, then exit\n" ^ 
-  "\t-print-passes prints intermediate data during compilation, then exit\n" ^
   "\t-print-units prints compilation units data, then exit\n"
 ;;
 
@@ -103,7 +102,6 @@ let _ =
     | "-exec" :: goal :: rest ->  batch := true; exec := goal; eat_options rest
     | "-print" :: rest -> print_lprolog := true; eat_options rest
     | "-print-ast" :: rest -> print_ast := true; eat_options rest
-    | "-print-passes" :: rest -> print_passes := true; eat_options rest
     | "-print-units" :: rest -> print_units := true; eat_options rest
     | "-parse-term" :: rest -> parse_term := true; eat_options rest
     | "-document-builtins" :: rest -> doc_builtins := true; eat_options rest
@@ -129,7 +127,6 @@ let _ =
   let paths = tjpath @ installpath @ [execpath] @ !extra_paths in
   let flags = {
       API.Compile.defined_variables = !vars;
-      API.Compile.print_passes = !print_passes;
       API.Compile.print_units = !print_units;
   } in
   if !doc_infix then begin
diff --git a/src/API.ml b/src/API.ml
index dce553e8..3fb87fcc 100644
--- a/src/API.ml
+++ b/src/API.ml
@@ -163,6 +163,7 @@ module Compile = struct
   type program = Compiler.program
   type query = Compiler.query
   type executable = ED.executable
+  type scoped_program = Compiler.scoped_program
   type compilation_unit = Compiler.checked_compilation_unit
   type compilation_unit_signature = Compiler.checked_compilation_unit_signature
   exception CompileError = Compiler_data.CompileError
@@ -183,13 +184,14 @@ module Compile = struct
 
   type flags = Compiler.flags = {
     defined_variables : StrSet.t;
-    print_passes : bool;
     print_units : bool;
   }
   let default_flags = Compiler.default_flags
   let optimize = Compiler.optimize_query
+  let scope ?(flags=Compiler.default_flags) ~elpi:{ Setup.header } a =
+    Compiler.scoped_of_ast ~flags ~header a
   let unit ?(flags=Compiler.default_flags) ~elpi:{ Setup.header } ~base ?builtins x =
-    Compiler.unit_of_ast ~flags ~header ?builtins x |> Compiler.check_unit ~base
+    Compiler.unit_of_scoped ~flags ~header ?builtins x |> Compiler.check_unit ~base
 
   let extend ?(flags=Compiler.default_flags) ~base u = Compiler.append_unit ~flags ~base u
   let signature u = Compiler.signature_of_checked_compilation_unit u
diff --git a/src/API.mli b/src/API.mli
index 76981160..013a0d12 100644
--- a/src/API.mli
+++ b/src/API.mli
@@ -241,8 +241,6 @@ module Compile : sig
   type flags = {
     (* variables used in conditional compilation, that is :if clauses *)
     defined_variables : StrSet.t;
-    (* debug: print intermediate data during the compilation phase *)
-    print_passes : bool;
     (* debug: print compilation units *)
     print_units : bool;
   }
@@ -267,8 +265,8 @@ module Compile : sig
    *)
   val program : ?flags:flags -> elpi:Setup.elpi -> Ast.program list -> program
 
-  (* separate compilation API: units are marshalable and closed w.r.t.
-     the host application (eg quotations are desugared).
+  (* separate compilation API: scoped_programs and units are marshalable and
+     closed w.r.t. the host application (eg quotations are desugared).
 
      Note:
      - macros and shorten directives part of a unit are not visible in other
@@ -278,10 +276,13 @@ module Compile : sig
      - types, type abbreviations and mode declarations from the  units are
        merged at assembly time
 *)
+  type scoped_program
+  val scope : ?flags:flags -> elpi:Setup.elpi -> Ast.program -> scoped_program
+  
   type compilation_unit
   type compilation_unit_signature
   val empty_base : elpi:Setup.elpi -> program
-  val unit : ?flags:flags -> elpi:Setup.elpi -> base:program -> ?builtins:Setup.builtins list -> Ast.program -> compilation_unit
+  val unit : ?flags:flags -> elpi:Setup.elpi -> base:program -> ?builtins:Setup.builtins list -> scoped_program -> compilation_unit
   val extend : ?flags:flags -> base:program -> compilation_unit -> program
 
   (* only adds the types/modes from the compilation unit, not its code *)
diff --git a/src/compiler/compiler.ml b/src/compiler/compiler.ml
index 01a83b67..8e61b6ed 100644
--- a/src/compiler/compiler.ml
+++ b/src/compiler/compiler.ml
@@ -16,14 +16,12 @@ let error = Compiler_data.error
 
 type flags = {
   defined_variables : StrSet.t;
-  print_passes : bool;
   print_units : bool;
 }
 [@@deriving show]
 
 let default_flags = {
   defined_variables = StrSet.empty;
-  print_passes = false;
   print_units = false;
 }
 
@@ -375,6 +373,12 @@ type program = {
 
 end
 
+type scoped_program = {
+  version : string;
+  code : Scoped.program;
+}
+[@@deriving show]
+
 type unchecked_compilation_unit = {
   version : string;
   code : Flat.program;
@@ -780,7 +784,7 @@ let get_mtm, set_mtm, drop_mtm, update_mtm =
 
 module Scope_Quotation_Macro : sig
 
-  val run : State.t -> toplevel_macros:macro_declaration -> Ast.Structured.program -> State.t * Scoped.program
+  val run : State.t -> toplevel_macros:macro_declaration -> Ast.Structured.program -> Scoped.program
   val check_duplicate_mode : F.t -> (mode * Loc.t) -> (mode * Loc.t) F.Map.t -> unit
   val scope_loc_term : state:State.t -> Ast.Term.t -> ScopedTerm.t
 
@@ -1059,7 +1063,7 @@ end = struct
       let body = scope_loc_term ~state:(set_mtm state { empty_mtm with macros = m }) body in
       F.Map.add name (body,loc) am, F.Map.add name (body,loc) m
 
-  let run state ~toplevel_macros p : State.t * Scoped.program =
+  let run state ~toplevel_macros p : Scoped.program =
 
     let rec compile_program omacros state { Ast.Structured.macros; kinds; types; type_abbrevs; modes; body } =
       let toplevel_macros, active_macros = List.fold_left (compile_macro state) (F.Map.empty,omacros) macros in
@@ -1071,62 +1075,62 @@ end = struct
       let defs_k = defs_of_map kinds in
       let defs_t = defs_of_map types in
       let defs_ta = defs_of_assoclist type_abbrevs in
-      let state, kinds, types, type_abbrevs, modes, defs_b, body =
+      let kinds, types, type_abbrevs, modes, defs_b, body =
         compile_body active_macros kinds types type_abbrevs modes F.Set.empty state body in
       let symbols = F.Set.(union (union (union (union defs_k defs_m) defs_t) defs_b) defs_ta) in
-      (state : State.t), toplevel_macros,
+      toplevel_macros,
       { Scoped.types; kinds; type_abbrevs; modes; body; symbols }
 
     and compile_body macros kinds types type_abbrevs (modes : (mode * Loc.t) F.Map.t) (defs : F.Set.t) state = function
-      | [] -> state, kinds, types, type_abbrevs, modes, defs, []
+      | [] -> kinds, types, type_abbrevs, modes, defs, []
       | Clauses cl :: rest ->
           let compiled_cl = List.map (compile_clause state macros) cl in
           let defs = F.Set.union defs (global_hd_symbols_of_clauses compiled_cl) in
-          let state, kinds, types, type_abbrevs, modes, defs, compiled_rest =
+          let kinds, types, type_abbrevs, modes, defs, compiled_rest =
             compile_body macros kinds types type_abbrevs modes defs state rest in
           let compiled_rest =
             match compiled_rest with
             | Scoped.Clauses l :: rest -> Scoped.Clauses (compiled_cl @ l) :: rest
             | rest -> Scoped.Clauses compiled_cl :: rest in
-          state, kinds, types, type_abbrevs, modes, defs, compiled_rest
+          kinds, types, type_abbrevs, modes, defs, compiled_rest
       | Namespace (prefix, p) :: rest ->
           let prefix = F.show prefix in
-          let state, _, p = compile_program macros state p in
-          let state, kinds, types, type_abbrevs, modes, defs, compiled_rest =
+          let _, p = compile_program macros state p in
+          let kinds, types, type_abbrevs, modes, defs, compiled_rest =
             compile_body macros kinds types type_abbrevs modes defs state rest in
           let symbols = prepend [prefix] p.Scoped.symbols in
-          state, kinds, types, type_abbrevs, modes, F.Set.union defs symbols,
+          kinds, types, type_abbrevs, modes, F.Set.union defs symbols,
           Scoped.Namespace(prefix, p) :: compiled_rest
       | Shorten(shorthands,p) :: rest ->
           let shorts = List.fold_left (fun s { Ast.Structured.short_name } ->
             F.Set.add short_name s) F.Set.empty shorthands in
-          let state, _, p = compile_program macros state p in
-          let state, kinds, types, type_abbrevs, modes, defs, compiled_rest =
+          let _, p = compile_program macros state p in
+          let kinds, types, type_abbrevs, modes, defs, compiled_rest =
             compile_body macros kinds types type_abbrevs modes defs state rest in
-          state, kinds, types, type_abbrevs, modes,
+          kinds, types, type_abbrevs, modes,
           F.Set.union defs (F.Set.diff p.Scoped.symbols shorts),
           Scoped.Shorten(shorthands, p) :: compiled_rest
       | Constraints ({ctx_filter; clique; rules}, p) :: rest ->
           (* XXX missing check for nested constraints *)
           let rules = List.map (compile_chr_rule state macros) rules in
-          let state, _, p = compile_program macros state p in
-          let state, kinds, types, type_abbrevs, modes, defs, compiled_rest =
+          let _, p = compile_program macros state p in
+          let kinds, types, type_abbrevs, modes, defs, compiled_rest =
             compile_body macros kinds types type_abbrevs modes defs state rest in
-          state, kinds, types, type_abbrevs, modes,
+          kinds, types, type_abbrevs, modes,
           F.Set.union defs p.Scoped.symbols,
           Scoped.Constraints({ctx_filter; clique; rules},p) :: compiled_rest
       | Accumulated p :: rest ->
-          let state, _, p = compile_program macros state p in
-          let state, kinds, types, type_abbrevs, modes, defs, compiled_rest =
+          let _, p = compile_program macros state p in
+          let kinds, types, type_abbrevs, modes, defs, compiled_rest =
             compile_body macros kinds types type_abbrevs modes defs state rest in
-          state, kinds, types, type_abbrevs, modes,
+          kinds, types, type_abbrevs, modes,
           F.Set.union defs p.Scoped.symbols,
           Scoped.Accumulated p :: compiled_rest
   
     in
-    let state, toplevel_macros, pbody = compile_program toplevel_macros state p in
+    let toplevel_macros, pbody = compile_program toplevel_macros state p in
     (* Printf.eprintf "run: %d\n%!" (F.Map.cardinal toplevel_macros); *)
-    state, { Scoped.pbody; toplevel_macros }
+    { Scoped.pbody; toplevel_macros }
 
 end
 
@@ -2005,32 +2009,19 @@ end
   API
  ****************************************************************************)
 
-(* Compiler passes *)
-let unit_or_header_of_ast { print_passes } s ~toplevel_macros ~builtins p =
-
-  if print_passes then
-    Format.eprintf "== AST ================@\n@[<v 0>%a@]@\n"
-      Ast.Program.pp p;
-
+let scope s ~toplevel_macros p : scoped_program =
   let p = RecoverStructure.run s p in
+  let p = Scope_Quotation_Macro.run ~toplevel_macros s p in
+  {
+    version = "%%VERSION_NUM%%";
+    code = p;
+  }
 
-  if print_passes then
-    Format.eprintf "== Ast.Structured ================@\n@[<v 0>%a@]@\n"
-      Ast.Structured.pp_program p;
-
-  let s, p = Scope_Quotation_Macro.run ~toplevel_macros s p in
-
-  if print_passes then
-    Format.eprintf "== Scoped ================@\n@[<v 0>%a@]@\n"
-      Scoped.pp_program p;
-
-  let p = Flatten.run s p in
-
-  if print_passes then
-    Format.eprintf "== Flat ================@\n@[<v 0>%a@]@\n"
-      Flat.pp_program p;
-
-  s, {
+(* Compiler passes *)
+let unit_or_header_of_scoped s ~builtins (p : scoped_program) : unchecked_compilation_unit =
+  assert ("%%VERSION_NUM%%" = p.version);
+  let p = Flatten.run s p.code in
+  {
     version = "%%VERSION_NUM%%";
     code = { p with builtins };
   }
@@ -2047,12 +2038,6 @@ let assemble_unit ~flags ~header:(s,base) units : program =
 
   let s, p = Assemble.extend flags s base units in
 
-  let { print_passes } = flags in
-
-  if print_passes then
-    Format.eprintf "== Assembled ================@\n@[<v 0>%a@]@\n"
-      Assembled.pp_program p;
-
  s, p
 ;;
 
@@ -2084,7 +2069,8 @@ let header_of_ast ~flags ~parser:p state_descriptor quotation_descriptor hoas_de
     List.map (fun (_,decl) -> decl |> List.filter_map (function
       | Data.BuiltInPredicate.MLCode (p,_) -> Some p
       | _ -> None)) builtins in
-  let state, u = unit_or_header_of_ast ~toplevel_macros:F.Map.empty flags state ~builtins ast in
+  let scoped_ast = scope ~toplevel_macros:F.Map.empty state ast in
+  let u = unit_or_header_of_scoped state ~builtins scoped_ast in
   print_unit flags u;
   let base = Assembled.empty () in
   let u = Check.check state ~base u in
@@ -2098,54 +2084,33 @@ let check_unit ~base:(st,base) u = Check.check st ~base u
 
 let empty_base ~header:b = b
 
-let unit_of_ast ~flags ~header:(s, u) ?(builtins=[]) p : unchecked_compilation_unit =
-  (* Printf.eprintf "unit_of_ast: %d\n%!" (F.Map.cardinal u.Assembled.toplevel_macros); *)
+let scoped_of_ast ~flags:_ ~header:(s,u) p =
+  scope ~toplevel_macros:u.Assembled.signature.toplevel_macros s p
+
+let unit_of_scoped ~flags ~header:(s, u) ?(builtins=[]) p : unchecked_compilation_unit =
   let builtins =
     List.flatten @@
     List.map (fun (_,decl) -> decl |> List.filter_map (function
       | Data.BuiltInPredicate.MLCode (p,_) -> Some p
       | _ -> error "Only BuiltInPredicate.MLCode allowed in units")) builtins in
-  let _, u = unit_or_header_of_ast flags s ~toplevel_macros:u.Assembled.signature.toplevel_macros ~builtins p in
+  let u = unit_or_header_of_scoped s ~builtins p in
   print_unit flags u;
   u
 
 let append_unit ~flags ~base:(s,p) unit : program =
-  let s, p = Assemble.extend flags s p unit in
-  let { print_passes } = flags in
-
-  if print_passes then
-    Format.eprintf "== Assembled ================@\n@[<v 0>%a@]@\n"
-     Assembled.pp_program p;
-
-  s, p
+  Assemble.extend flags s p unit
 
 let append_unit_signature ~flags ~base:(s,p) unit : program =
-  let s, p = Assemble.extend_signature s p unit in
-  let { print_passes } = flags in
-
-  if print_passes then
-    Format.eprintf "== Assembled ================@\n@[<v 0>%a@]@\n"
-      Assembled.pp_program p;
-
-  s, p
+  Assemble.extend_signature s p unit
   
 let program_of_ast ~flags ~header:((st, base) as header : State.t * Assembled.program) p : program =
-  let u = unit_of_ast ~flags ~header p in
+  let p = scoped_of_ast ~flags ~header p in
+  let u = unit_of_scoped ~flags ~header p in
   let u = Check.check st ~base u in
   assemble_unit ~flags ~header u
 
 let total_type_checking_time { WithMain.total_type_checking_time = x } = x
 
-(* let uvbodies_of_assignments assignments =
-  (* Clients may add spurious args that, not occurring in the query,
-     are not turned into uvars *)
-   let assignments = assignments |> StrMap.filter (fun _ -> function
-     | UVar _ | AppUVar _ -> true
-     | _ -> false) in
-   State.end_goal_compilation (StrMap.map (function
-     | UVar(b,_,_) | AppUVar(b,_,_) -> b
-     | _ -> assert false) assignments) *)
-
 let pp fmt ub =
   R.Pp.uppterm 0 [] ~argsdepth:0 [||] fmt (D.mkUVar ub 0 0)
   
diff --git a/src/compiler/compiler.mli b/src/compiler/compiler.mli
index bb557df9..be48a847 100644
--- a/src/compiler/compiler.mli
+++ b/src/compiler/compiler.mli
@@ -11,7 +11,6 @@ open Data
 
 type flags = {
   defined_variables : StrSet.t;
-  print_passes : bool; (* debug *)
   print_units : bool; (* debug *)
 }
 val default_flags : flags
@@ -24,10 +23,13 @@ val header_of_ast : flags:flags -> parser:(module Parse.Parser) -> State.descrip
 type program
 val program_of_ast : flags:flags -> header:header -> Ast.Program.t -> program
 
+type scoped_program
+val scoped_of_ast : flags:flags -> header:header -> Ast.Program.t -> scoped_program
+
 type checked_compilation_unit
 type unchecked_compilation_unit
 val empty_base : header:header -> program
-val unit_of_ast : flags:flags -> header:header -> ?builtins:builtins list -> Ast.Program.t -> unchecked_compilation_unit
+val unit_of_scoped : flags:flags -> header:header -> ?builtins:builtins list -> scoped_program -> unchecked_compilation_unit
 val append_unit : flags:flags -> base:program -> checked_compilation_unit -> program
 val check_unit : base:program -> unchecked_compilation_unit -> checked_compilation_unit
 
diff --git a/tests/sources/sepcomp_template.ml b/tests/sources/sepcomp_template.ml
index b5b73c1d..74aa93c5 100644
--- a/tests/sources/sepcomp_template.ml
+++ b/tests/sources/sepcomp_template.ml
@@ -6,8 +6,9 @@ let init () =
 let cc ~elpi ~flags ~base i u =
   let u =
     Compile.unit ~elpi ~flags ~base
+     (Compile.scope ~elpi ~flags
       (Parse.program_from ~elpi ~loc:(Ast.Loc.initial (Printf.sprintf "<u%d>" i))
-        (Lexing.from_string u)) in
+        (Lexing.from_string u))) in
   Compile.extend ~flags ~base u, u