diff --git a/src/haz3lweb/DebugConsole.re b/src/haz3lweb/DebugConsole.re
index 8f7a0b12b0..1d61f460b2 100644
--- a/src/haz3lweb/DebugConsole.re
+++ b/src/haz3lweb/DebugConsole.re
@@ -16,7 +16,7 @@ let print = ({settings, editors, _}: Model.t, key: string): unit => {
     |> Zipper.unselect_and_zip
     |> ((seg: Segment.t(Uuidm.t)) => [%derive.show: Segment.t(Id.t)](seg))
     |> print
-  | "F3" => term |> [%derive.show: UExp.t(list(Id.t))] |> print
+  | "F3" => term |> [%derive.show: UExp.t(IdTag.t)] |> print
   | "F4" => map |> Statics.Map.show |> print
   | "F5" =>
     let env = Editors.get_env_init(~settings, editors);
diff --git a/src/haz3lweb/Editors.re b/src/haz3lweb/Editors.re
index 7b5512fc10..5f3c3ca377 100644
--- a/src/haz3lweb/Editors.re
+++ b/src/haz3lweb/Editors.re
@@ -66,7 +66,7 @@ let perform_action =
 let update_current_editor_statics = settings =>
   update(Editor.update_statics(~settings));
 
-let get_ctx_init = (~settings as _: Settings.t, editors: t): Ctx.t =>
+let get_ctx_init = (~settings as _: Settings.t, editors: t): Ctx.t(IdTag.t) =>
   switch (editors) {
   | Scratch(_)
   | Exercises(_)
diff --git a/src/haz3lweb/view/CtxInspector.re b/src/haz3lweb/view/CtxInspector.re
index 81b3050cc7..46f26c2797 100644
--- a/src/haz3lweb/view/CtxInspector.re
+++ b/src/haz3lweb/view/CtxInspector.re
@@ -5,7 +5,8 @@ open Util.Web;
 let jump_to = entry =>
   UpdateAction.PerformAction(Jump(TileId(Haz3lcore.Ctx.get_id(entry))));
 
-let context_entry_view = (~inject, entry: Haz3lcore.Ctx.entry): Node.t => {
+let context_entry_view =
+    (~inject, entry: Haz3lcore.Ctx.entry(Haz3lcore.IdTag.t)): Node.t => {
   let div_name =
     div(
       ~attrs=[clss(["name"]), Attr.on_click(_ => inject(jump_to(entry)))],
@@ -33,7 +34,7 @@ let context_entry_view = (~inject, entry: Haz3lcore.Ctx.entry): Node.t => {
   };
 };
 
-let ctx_view = (~inject, ctx: Haz3lcore.Ctx.t): Node.t =>
+let ctx_view = (~inject, ctx: Haz3lcore.Ctx.t(Haz3lcore.IdTag.t)): Node.t =>
   div(
     ~attrs=[clss(["context-entries"])],
     List.map(
diff --git a/src/haz3lweb/view/ExplainThis.re b/src/haz3lweb/view/ExplainThis.re
index 40fc6f1b45..87d555721d 100644
--- a/src/haz3lweb/view/ExplainThis.re
+++ b/src/haz3lweb/view/ExplainThis.re
@@ -392,7 +392,7 @@ let example_view =
     ];
 };
 
-let rec bypass_parens_and_annot_pat = (pat: Pat.t) => {
+let rec bypass_parens_and_annot_pat = (pat: Pat.t(IdTag.t)) => {
   switch (pat.term) {
   | Parens(p)
   | Cast(p, _, _) => bypass_parens_and_annot_pat(p)
@@ -400,21 +400,21 @@ let rec bypass_parens_and_annot_pat = (pat: Pat.t) => {
   };
 };
 
-let rec bypass_parens_pat = (pat: Pat.t) => {
+let rec bypass_parens_pat = (pat: Pat.t(IdTag.t)) => {
   switch (pat.term) {
   | Parens(p) => bypass_parens_pat(p)
   | _ => pat
   };
 };
 
-let rec bypass_parens_exp = (exp: Exp.t(list(Id.t))) => {
+let rec bypass_parens_exp = (exp: Exp.t(IdTag.t)) => {
   switch (exp.term) {
   | Parens(e) => bypass_parens_exp(e)
   | _ => exp
   };
 };
 
-let rec bypass_parens_typ = (typ: Typ.t) => {
+let rec bypass_parens_typ = (typ: Typ.t(IdTag.t)) => {
   switch (typ.term) {
   | Parens(t) => bypass_parens_typ(t)
   | _ => typ
@@ -532,7 +532,7 @@ let get_doc =
     let rec get_message_exp =
             (term)
             : (list(Node.t), (list(Node.t), ColorSteps.t), list(Node.t)) =>
-      switch ((term: Exp.term(list(Id.t)))) {
+      switch ((term: Exp.term(IdTag.t))) {
       | Exp.Invalid(_) => simple("Not a valid expression")
       | DynamicErrorHole(_)
       | FailedCast(_)
@@ -542,8 +542,8 @@ let get_doc =
       | EmptyHole => get_message(HoleExp.empty_hole_exps)
       | MultiHole(_children) => get_message(HoleExp.multi_hole_exps)
       | TyAlias(ty_pat, ty_def, _body) =>
-        let tpat_id = List.nth(ty_pat.ids, 0);
-        let def_id = List.nth(ty_def.ids, 0);
+        let tpat_id = List.nth(ty_pat.annotation.ids, 0);
+        let def_id = List.nth(ty_def.annotation.ids, 0);
         get_message(
           ~colorings=
             TyAliasExp.tyalias_base_exp_coloring_ids(~tpat_id, ~def_id),
@@ -578,8 +578,8 @@ let get_doc =
         )
       | TypFun(tpat, body, _) =>
         let basic = group_id => {
-          let tpat_id = List.nth(tpat.ids, 0);
-          let body_id = List.nth(body.ids, 0);
+          let tpat_id = List.nth(tpat.annotation.ids, 0);
+          let body_id = List.nth(body.annotation.ids, 0);
           get_message(
             ~colorings=
               FunctionExp.function_exp_coloring_ids(
@@ -602,8 +602,8 @@ let get_doc =
         basic(TypFunctionExp.type_functions_basic);
       | Fun(pat, body, _, _) =>
         let basic = group_id => {
-          let pat_id = List.nth(pat.ids, 0);
-          let body_id = List.nth(body.ids, 0);
+          let pat_id = List.nth(pat.annotation.ids, 0);
+          let body_id = List.nth(body.annotation.ids, 0);
           get_message(
             ~colorings=
               FunctionExp.function_exp_coloring_ids(~pat_id, ~body_id),
@@ -620,8 +620,8 @@ let get_doc =
           );
         };
         let pat = bypass_parens_and_annot_pat(pat);
-        let pat_id = List.nth(pat.ids, 0);
-        let body_id = List.nth(body.ids, 0);
+        let pat_id = List.nth(pat.annotation.ids, 0);
+        let body_id = List.nth(body.annotation.ids, 0);
         switch (pat.term) {
         | EmptyHole =>
           if (FunctionExp.function_empty_hole_exp.id
@@ -864,8 +864,8 @@ let get_doc =
         | Cons(hd, tl) =>
           if (FunctionExp.function_cons_exp.id
               == get_specificity_level(FunctionExp.functions_cons)) {
-            let hd_id = List.nth(hd.ids, 0);
-            let tl_id = List.nth(tl.ids, 0);
+            let hd_id = List.nth(hd.annotation.ids, 0);
+            let tl_id = List.nth(tl.annotation.ids, 0);
             get_message(
               ~colorings=
                 FunctionExp.function_cons_exp_coloring_ids(
@@ -910,8 +910,8 @@ let get_doc =
             basic(FunctionExp.functions_var);
           }
         | Tuple(elements) =>
-          let pat_id = List.nth(pat.ids, 0);
-          let body_id = List.nth(body.ids, 0);
+          let pat_id = List.nth(pat.annotation.ids, 0);
+          let body_id = List.nth(body.annotation.ids, 0);
           let basic_tuple = group_id => {
             get_message(
               ~colorings=
@@ -938,8 +938,10 @@ let get_doc =
           | 2 =>
             let doc_id = get_specificity_level(FunctionExp.functions_tuple2);
             if (FunctionExp.function_tuple2_exp.id == doc_id) {
-              let pat1_id = List.nth(List.nth(elements, 0).ids, 0);
-              let pat2_id = List.nth(List.nth(elements, 1).ids, 0);
+              let pat1_id =
+                List.nth(List.nth(elements, 0).annotation.ids, 0);
+              let pat2_id =
+                List.nth(List.nth(elements, 1).annotation.ids, 0);
               get_message(
                 ~colorings=
                   FunctionExp.function_tuple2_exp_coloring_ids(
@@ -967,9 +969,12 @@ let get_doc =
           | 3 =>
             let doc_id = get_specificity_level(FunctionExp.functions_tuple3);
             if (FunctionExp.function_tuple3_exp.id == doc_id) {
-              let pat1_id = List.nth(List.nth(elements, 0).ids, 0);
-              let pat2_id = List.nth(List.nth(elements, 1).ids, 0);
-              let pat3_id = List.nth(List.nth(elements, 2).ids, 0);
+              let pat1_id =
+                List.nth(List.nth(elements, 0).annotation.ids, 0);
+              let pat2_id =
+                List.nth(List.nth(elements, 1).annotation.ids, 0);
+              let pat3_id =
+                List.nth(List.nth(elements, 2).annotation.ids, 0);
               get_message(
                 ~colorings=
                   FunctionExp.function_tuple3_exp_coloring_ids(
@@ -1007,8 +1012,8 @@ let get_doc =
         | Ap(con, arg) =>
           if (FunctionExp.function_ap_exp.id
               == get_specificity_level(FunctionExp.functions_ap)) {
-            let con_id = List.nth(con.ids, 0);
-            let arg_id = List.nth(arg.ids, 0);
+            let con_id = List.nth(con.annotation.ids, 0);
+            let arg_id = List.nth(arg.annotation.ids, 0);
             get_message(
               ~colorings=
                 FunctionExp.function_ap_exp_coloring_ids(
@@ -1034,8 +1039,8 @@ let get_doc =
         | Constructor(v, _) =>
           if (FunctionExp.function_ctr_exp.id
               == get_specificity_level(FunctionExp.functions_ctr)) {
-            let pat_id = List.nth(pat.ids, 0);
-            let body_id = List.nth(body.ids, 0);
+            let pat_id = List.nth(pat.annotation.ids, 0);
+            let body_id = List.nth(body.annotation.ids, 0);
             get_message(
               ~colorings=
                 FunctionExp.function_ctr_exp_coloring_ids(~pat_id, ~body_id),
@@ -1076,8 +1081,8 @@ let get_doc =
         | 2 =>
           if (TupleExp.tuple_exp_size2.id
               == get_specificity_level(TupleExp.tuples2)) {
-            let exp1_id = List.nth(List.nth(terms, 0).ids, 0);
-            let exp2_id = List.nth(List.nth(terms, 1).ids, 0);
+            let exp1_id = List.nth(List.nth(terms, 0).annotation.ids, 0);
+            let exp2_id = List.nth(List.nth(terms, 1).annotation.ids, 0);
             get_message(
               ~colorings=
                 TupleExp.tuple_exp_size2_coloring_ids(~exp1_id, ~exp2_id),
@@ -1098,9 +1103,9 @@ let get_doc =
         | 3 =>
           if (TupleExp.tuple_exp_size3.id
               == get_specificity_level(TupleExp.tuples3)) {
-            let exp1_id = List.nth(List.nth(terms, 0).ids, 0);
-            let exp2_id = List.nth(List.nth(terms, 1).ids, 0);
-            let exp3_id = List.nth(List.nth(terms, 2).ids, 0);
+            let exp1_id = List.nth(List.nth(terms, 0).annotation.ids, 0);
+            let exp2_id = List.nth(List.nth(terms, 1).annotation.ids, 0);
+            let exp3_id = List.nth(List.nth(terms, 2).annotation.ids, 0);
             get_message(
               ~colorings=
                 TupleExp.tuple_exp_size3_coloring_ids(
@@ -1128,9 +1133,9 @@ let get_doc =
       | Var(n) => get_message(TerminalExp.var_exps(n))
       | Let(pat, def, body) =>
         let pat = bypass_parens_and_annot_pat(pat);
-        let pat_id = List.nth(pat.ids, 0);
-        let def_id = List.nth(def.ids, 0);
-        let body_id = List.nth(body.ids, 0);
+        let pat_id = List.nth(pat.annotation.ids, 0);
+        let def_id = List.nth(def.annotation.ids, 0);
+        let body_id = List.nth(body.annotation.ids, 0);
         let basic = group_id => {
           get_message(
             ~colorings=LetExp.let_base_exp_coloring_ids(~pat_id, ~def_id),
@@ -1387,8 +1392,8 @@ let get_doc =
         | Cons(hd, tl) =>
           if (LetExp.let_cons_exp.id
               == get_specificity_level(LetExp.lets_cons)) {
-            let hd_id = List.nth(hd.ids, 0);
-            let tl_id = List.nth(tl.ids, 0);
+            let hd_id = List.nth(hd.annotation.ids, 0);
+            let tl_id = List.nth(tl.annotation.ids, 0);
             get_message(
               ~colorings=
                 LetExp.let_cons_exp_coloring_ids(~hd_id, ~tl_id, ~def_id),
@@ -1450,8 +1455,10 @@ let get_doc =
           | 2 =>
             let doc_id = get_specificity_level(LetExp.lets_tuple2);
             if (LetExp.let_tuple2_exp.id == doc_id) {
-              let pat1_id = List.nth(List.nth(elements, 0).ids, 0);
-              let pat2_id = List.nth(List.nth(elements, 1).ids, 0);
+              let pat1_id =
+                List.nth(List.nth(elements, 0).annotation.ids, 0);
+              let pat2_id =
+                List.nth(List.nth(elements, 1).annotation.ids, 0);
               get_message(
                 ~colorings=
                   LetExp.let_tuple2_exp_coloring_ids(
@@ -1480,9 +1487,12 @@ let get_doc =
             let doc_id = get_specificity_level(LetExp.lets_tuple3);
             // TODO Syntactic form can go off page - so can examples - but can scroll, just can't see bottom scroll bar
             if (LetExp.let_tuple3_exp.id == doc_id) {
-              let pat1_id = List.nth(List.nth(elements, 0).ids, 0);
-              let pat2_id = List.nth(List.nth(elements, 1).ids, 0);
-              let pat3_id = List.nth(List.nth(elements, 2).ids, 0);
+              let pat1_id =
+                List.nth(List.nth(elements, 0).annotation.ids, 0);
+              let pat2_id =
+                List.nth(List.nth(elements, 1).annotation.ids, 0);
+              let pat3_id =
+                List.nth(List.nth(elements, 2).annotation.ids, 0);
               get_message(
                 ~colorings=
                   LetExp.let_tuple3_exp_coloring_ids(
@@ -1519,8 +1529,8 @@ let get_doc =
           };
         | Ap(con, arg) =>
           if (LetExp.let_ap_exp.id == get_specificity_level(LetExp.lets_ap)) {
-            let con_id = List.nth(con.ids, 0);
-            let arg_id = List.nth(arg.ids, 0);
+            let con_id = List.nth(con.annotation.ids, 0);
+            let arg_id = List.nth(arg.annotation.ids, 0);
             get_message(
               ~colorings=
                 LetExp.let_ap_exp_coloring_ids(~con_id, ~arg_id, ~def_id),
@@ -1580,8 +1590,8 @@ let get_doc =
           ),
         )
       | TypAp(f, typ) =>
-        let f_id = List.nth(f.ids, 0);
-        let typ_id = List.nth(typ.ids, 0);
+        let f_id = List.nth(f.annotation.ids, 0);
+        let typ_id = List.nth(typ.annotation.ids, 0);
         let basic = (group, format, coloring_ids) => {
           get_message(
             ~colorings=coloring_ids(~f_id, ~typ_id),
@@ -1601,8 +1611,8 @@ let get_doc =
         );
 
       | Ap(Forward, x, arg) =>
-        let x_id = List.nth(x.ids, 0);
-        let arg_id = List.nth(arg.ids, 0);
+        let x_id = List.nth(x.annotation.ids, 0);
+        let arg_id = List.nth(arg.annotation.ids, 0);
         let basic = (group, format, coloring_ids) => {
           get_message(
             ~colorings=coloring_ids(~x_id, ~arg_id),
@@ -1636,11 +1646,11 @@ let get_doc =
           )
         };
       | DeferredAp(x, args) =>
-        let x_id = List.nth(x.ids, 0);
+        let x_id = List.nth(x.annotation.ids, 0);
         let supplied_id = Id.mk();
         let deferred_id = {
           let deferral = List.find(Exp.is_deferral, args);
-          List.nth(deferral.ids, 0);
+          List.nth(deferral.annotation.ids, 0);
         };
         switch (mode) {
         | MessageContent(_) =>
@@ -1663,8 +1673,8 @@ let get_doc =
           let color_fn = List.nth(ColorSteps.child_colors, 0);
           let color_supplied = List.nth(ColorSteps.child_colors, 1);
           let color_deferred = List.nth(ColorSteps.child_colors, 2);
-          let add = (mapping, arg: Exp.t(list(Id.t))) => {
-            let arg_id = List.nth(arg.ids, 0);
+          let add = (mapping, arg: Exp.t(IdTag.t)) => {
+            let arg_id = List.nth(arg.annotation.ids, 0);
             Haz3lcore.Id.Map.add(
               arg_id,
               Exp.is_deferral(arg) ? color_deferred : color_supplied,
@@ -1677,9 +1687,9 @@ let get_doc =
           ([], ([], color_map), []);
         };
       | If(cond, then_, else_) =>
-        let cond_id = List.nth(cond.ids, 0);
-        let then_id = List.nth(then_.ids, 0);
-        let else_id = List.nth(else_.ids, 0);
+        let cond_id = List.nth(cond.annotation.ids, 0);
+        let then_id = List.nth(then_.annotation.ids, 0);
+        let else_id = List.nth(else_.annotation.ids, 0);
         get_message(
           ~colorings=IfExp.if_exp_coloring_ids(~cond_id, ~then_id, ~else_id),
           ~format=
@@ -1695,8 +1705,8 @@ let get_doc =
           IfExp.ifs,
         );
       | Seq(left, right) =>
-        let exp1_id = List.nth(left.ids, 0);
-        let exp2_id = List.nth(right.ids, 0);
+        let exp1_id = List.nth(left.annotation.ids, 0);
+        let exp2_id = List.nth(right.annotation.ids, 0);
         get_message(
           ~colorings=SeqExp.seq_exp_coloring_ids(~exp1_id, ~exp2_id),
           ~format=
@@ -1740,7 +1750,7 @@ let get_doc =
         )
       | Filter(_) => simple("Internal expression")
       | Test(body) =>
-        let body_id = List.nth(body.ids, 0);
+        let body_id = List.nth(body.annotation.ids, 0);
         get_message(
           ~colorings=TestExp.test_exp_coloring_ids(~body_id),
           ~format=
@@ -1755,8 +1765,8 @@ let get_doc =
         );
       | Parens(term) => get_message_exp(term.term) // No Special message?
       | Cons(hd, tl) =>
-        let hd_id = List.nth(hd.ids, 0);
-        let tl_id = List.nth(tl.ids, 0);
+        let hd_id = List.nth(hd.annotation.ids, 0);
+        let tl_id = List.nth(tl.annotation.ids, 0);
         get_message(
           ~colorings=ListExp.cons_exp_coloring_ids(~hd_id, ~tl_id),
           ~format=
@@ -1771,8 +1781,8 @@ let get_doc =
           ListExp.listcons,
         );
       | ListConcat(xs, ys) =>
-        let xs_id = List.nth(xs.ids, 0);
-        let ys_id = List.nth(ys.ids, 0);
+        let xs_id = List.nth(xs.annotation.ids, 0);
+        let ys_id = List.nth(ys.annotation.ids, 0);
         get_message(
           ~colorings=ListExp.concat_exp_coloring_ids(~xs_id, ~ys_id),
           ~format=
@@ -1789,7 +1799,7 @@ let get_doc =
       | UnOp(op, exp) =>
         switch (op) {
         | Bool(Not) =>
-          let exp_id = List.nth(exp.ids, 0);
+          let exp_id = List.nth(exp.annotation.ids, 0);
           get_message(
             ~colorings=OpExp.bool_unary_not_exp_coloring_ids(~exp_id),
             ~format=
@@ -1803,7 +1813,7 @@ let get_doc =
             OpExp.bool_un_not,
           );
         | Int(Minus) =>
-          let exp_id = List.nth(exp.ids, 0);
+          let exp_id = List.nth(exp.annotation.ids, 0);
           get_message(
             ~colorings=OpExp.int_unary_minus_exp_coloring_ids(~exp_id),
             ~format=
@@ -1865,8 +1875,8 @@ let get_doc =
           | String(Equals) => (string_equal, str_eq_exp_coloring_ids)
           | String(Concat) => (string_concat, str_concat_exp_coloring_ids)
           };
-        let left_id = List.nth(left.ids, 0);
-        let right_id = List.nth(right.ids, 0);
+        let left_id = List.nth(left.annotation.ids, 0);
+        let right_id = List.nth(right.annotation.ids, 0);
         get_message(
           ~colorings=coloring_ids(~left_id, ~right_id),
           ~format=
@@ -1881,7 +1891,7 @@ let get_doc =
           group,
         );
       | Match(scrut, _rules) =>
-        let scrut_id = List.nth(scrut.ids, 0);
+        let scrut_id = List.nth(scrut.annotation.ids, 0);
         get_message(
           ~colorings=CaseExp.case_exp_coloring_ids(~scrut_id),
           ~format=
@@ -1963,8 +1973,8 @@ let get_doc =
         );
       }
     | Cons(hd, tl) =>
-      let hd_id = List.nth(hd.ids, 0);
-      let tl_id = List.nth(tl.ids, 0);
+      let hd_id = List.nth(hd.annotation.ids, 0);
+      let tl_id = List.nth(tl.annotation.ids, 0);
       let basic = doc =>
         get_message(
           ~colorings=ListPat.cons_base_pat_coloring_ids(~hd_id, ~tl_id),
@@ -1982,8 +1992,8 @@ let get_doc =
       switch (tl.term) {
       | Pat.Cons(hd2, tl2) =>
         if (ListPat.cons2_pat.id == get_specificity_level(ListPat.cons2)) {
-          let hd2_id = List.nth(hd2.ids, 0);
-          let tl2_id = List.nth(tl2.ids, 0);
+          let hd2_id = List.nth(hd2.annotation.ids, 0);
+          let tl2_id = List.nth(tl2.annotation.ids, 0);
           get_message(
             ~colorings=
               ListPat.cons2_pat_coloring_ids(
@@ -2033,8 +2043,8 @@ let get_doc =
       | 2 =>
         if (TuplePat.tuple_pat_size2.id
             == get_specificity_level(TuplePat.tuple2)) {
-          let elem1_id = List.nth(List.nth(elements, 0).ids, 0);
-          let elem2_id = List.nth(List.nth(elements, 1).ids, 0);
+          let elem1_id = List.nth(List.nth(elements, 0).annotation.ids, 0);
+          let elem2_id = List.nth(List.nth(elements, 1).annotation.ids, 0);
           get_message(
             ~colorings=
               TuplePat.tuple_pat_size2_coloring_ids(~elem1_id, ~elem2_id),
@@ -2055,9 +2065,9 @@ let get_doc =
       | 3 =>
         if (TuplePat.tuple_pat_size3.id
             == get_specificity_level(TuplePat.tuple3)) {
-          let elem1_id = List.nth(List.nth(elements, 0).ids, 0);
-          let elem2_id = List.nth(List.nth(elements, 1).ids, 0);
-          let elem3_id = List.nth(List.nth(elements, 2).ids, 0);
+          let elem1_id = List.nth(List.nth(elements, 0).annotation.ids, 0);
+          let elem2_id = List.nth(List.nth(elements, 1).annotation.ids, 0);
+          let elem3_id = List.nth(List.nth(elements, 2).annotation.ids, 0);
           get_message(
             ~colorings=
               TuplePat.tuple_pat_size3_coloring_ids(
@@ -2083,8 +2093,8 @@ let get_doc =
       | _ => basic(TuplePat.tuple)
       };
     | Ap(con, arg) =>
-      let con_id = List.nth(con.ids, 0);
-      let arg_id = List.nth(arg.ids, 0);
+      let con_id = List.nth(con.annotation.ids, 0);
+      let arg_id = List.nth(arg.annotation.ids, 0);
       get_message(
         ~colorings=AppPat.ap_pat_coloring_ids(~con_id, ~arg_id),
         ~format=
@@ -2107,8 +2117,8 @@ let get_doc =
         TerminalPat.ctr(con),
       )
     | Cast(pat, typ, _) =>
-      let pat_id = List.nth(pat.ids, 0);
-      let typ_id = List.nth(typ.ids, 0);
+      let pat_id = List.nth(pat.annotation.ids, 0);
+      let typ_id = List.nth(typ.annotation.ids, 0);
       get_message(
         ~colorings=TypAnnPat.typann_pat_coloring_ids(~pat_id, ~typ_id),
         ~format=
@@ -2138,7 +2148,7 @@ let get_doc =
     | Bool => get_message(TerminalTyp.bool)
     | String => get_message(TerminalTyp.str)
     | List(elem) =>
-      let elem_id = List.nth(elem.ids, 0);
+      let elem_id = List.nth(elem.annotation.ids, 0);
       get_message(
         ~colorings=ListTyp.list_typ_coloring_ids(~elem_id),
         ~format=
@@ -2152,8 +2162,8 @@ let get_doc =
         ListTyp.list,
       );
     | Forall(tpat, typ) =>
-      let tpat_id = List.nth(tpat.ids, 0);
-      let tbody_id = List.nth(typ.ids, 0);
+      let tpat_id = List.nth(tpat.annotation.ids, 0);
+      let tbody_id = List.nth(typ.annotation.ids, 0);
       get_message(
         ~colorings=ForallTyp.forall_typ_coloring_ids(~tpat_id, ~tbody_id),
         ~format=
@@ -2168,8 +2178,8 @@ let get_doc =
         ForallTyp.forall,
       );
     | Rec(tpat, typ) =>
-      let tpat_id = List.nth(tpat.ids, 0);
-      let tbody_id = List.nth(typ.ids, 0);
+      let tpat_id = List.nth(tpat.annotation.ids, 0);
+      let tbody_id = List.nth(typ.annotation.ids, 0);
       get_message(
         ~colorings=RecTyp.rec_typ_coloring_ids(~tpat_id, ~tbody_id),
         ~format=
@@ -2184,8 +2194,8 @@ let get_doc =
         RecTyp.rec_,
       );
     | Arrow(arg, result) =>
-      let arg_id = List.nth(arg.ids, 0);
-      let result_id = List.nth(result.ids, 0);
+      let arg_id = List.nth(arg.annotation.ids, 0);
+      let result_id = List.nth(result.annotation.ids, 0);
       let basic = doc =>
         get_message(
           ~colorings=ArrowTyp.arrow_typ_coloring_ids(~arg_id, ~result_id),
@@ -2203,8 +2213,8 @@ let get_doc =
       switch (result.term) {
       | Typ.Arrow(arg2, result2) =>
         if (ArrowTyp.arrow3_typ.id == get_specificity_level(ArrowTyp.arrow3)) {
-          let arg2_id = List.nth(arg2.ids, 0);
-          let result2_id = List.nth(result2.ids, 0);
+          let arg2_id = List.nth(arg2.annotation.ids, 0);
+          let result2_id = List.nth(result2.annotation.ids, 0);
           get_message(
             ~colorings=
               ArrowTyp.arrow3_typ_coloring_ids(
@@ -2255,8 +2265,8 @@ let get_doc =
         }
       | 2 =>
         if (TupleTyp.tuple2_typ.id == get_specificity_level(TupleTyp.tuple2)) {
-          let elem1_id = List.nth(List.nth(elements, 0).ids, 0);
-          let elem2_id = List.nth(List.nth(elements, 1).ids, 0);
+          let elem1_id = List.nth(List.nth(elements, 0).annotation.ids, 0);
+          let elem2_id = List.nth(List.nth(elements, 1).annotation.ids, 0);
           get_message(
             ~colorings=TupleTyp.tuple2_typ_coloring_ids(~elem1_id, ~elem2_id),
             ~format=
@@ -2275,9 +2285,9 @@ let get_doc =
         }
       | 3 =>
         if (TupleTyp.tuple3_typ.id == get_specificity_level(TupleTyp.tuple3)) {
-          let elem1_id = List.nth(List.nth(elements, 0).ids, 0);
-          let elem2_id = List.nth(List.nth(elements, 1).ids, 0);
-          let elem3_id = List.nth(List.nth(elements, 2).ids, 0);
+          let elem1_id = List.nth(List.nth(elements, 0).annotation.ids, 0);
+          let elem2_id = List.nth(List.nth(elements, 1).annotation.ids, 0);
+          let elem3_id = List.nth(List.nth(elements, 2).annotation.ids, 0);
           get_message(
             ~colorings=
               TupleTyp.tuple3_typ_coloring_ids(
diff --git a/src/haz3lweb/view/Kind.re b/src/haz3lweb/view/Kind.re
index 8feb3af0b0..a13659f229 100644
--- a/src/haz3lweb/view/Kind.re
+++ b/src/haz3lweb/view/Kind.re
@@ -2,7 +2,7 @@ open Virtual_dom.Vdom;
 open Node;
 open Util.Web;
 
-let view = (kind: Haz3lcore.Ctx.kind): Node.t =>
+let view = (kind: Haz3lcore.Ctx.kind(Haz3lcore.IdTag.t)): Node.t =>
   switch (kind) {
   | Singleton(ty) => div_c("kind-view", [Type.view(ty)])
   | Abstract => div_c("kind-view", [text("Type")])
diff --git a/src/haz3lweb/view/Type.re b/src/haz3lweb/view/Type.re
index 4ee4f29af2..cb9d9b0144 100644
--- a/src/haz3lweb/view/Type.re
+++ b/src/haz3lweb/view/Type.re
@@ -3,7 +3,7 @@ open Node;
 open Util.Web;
 open Haz3lcore;
 
-let tpat_view = (tpat: Haz3lcore.TPat.t): string =>
+let tpat_view = (tpat: Haz3lcore.TPat.t('a)): string =>
   switch (tpat.term) {
   | Var(x) => x
   | _ => "?"
@@ -15,13 +15,14 @@ let ty_view = (cls: string, s: string): Node.t =>
 let alias_view = (s: string): Node.t =>
   div(~attrs=[clss(["typ-alias-view"])], [text(s)]);
 
-let rec view_ty = (~strip_outer_parens=false, ty: Haz3lcore.Typ.t): Node.t =>
+let rec view_ty =
+        (~strip_outer_parens=false, ty: Haz3lcore.Typ.t(IdTag.t)): Node.t =>
   switch (Typ.term_of(ty)) {
   | Unknown(prov) =>
     div(
       ~attrs=[
         clss(["typ-view", "atom", "unknown"]),
-        Attr.title(Typ.show_type_provenance(prov)),
+        Attr.title([%derive.show: Typ.type_provenance(IdTag.t)](prov)),
       ],
       [text("?") /*, prov_view(prov)*/],
     )
@@ -98,7 +99,7 @@ let rec view_ty = (~strip_outer_parens=false, ty: Haz3lcore.Typ.t): Node.t =>
     div(
       ~attrs=[
         clss(["typ-view", "atom", "unknown"]),
-        Attr.title(Typ.show_type_provenance(Internal)),
+        Attr.title([%derive.show: Typ.type_provenance(IdTag.t)](Internal)),
       ],
       [text("?") /*, prov_view(prov)*/],
     )
@@ -120,5 +121,5 @@ and paren_view = typ =>
     [view_ty(typ)];
   };
 
-let view = (ty: Haz3lcore.Typ.t): Node.t =>
+let view = (ty: Haz3lcore.Typ.t(IdTag.t)): Node.t =>
   div_c("typ-wrapper", [view_ty(ty)]);
diff --git a/src/haz3lweb/view/dhcode/DHCode.re b/src/haz3lweb/view/dhcode/DHCode.re
index cdb22187a5..231341e262 100644
--- a/src/haz3lweb/view/dhcode/DHCode.re
+++ b/src/haz3lweb/view/dhcode/DHCode.re
@@ -135,7 +135,7 @@ let view =
       ~next_steps: list((int, Id.t))=[],
       ~result_key: string,
       ~infomap,
-      d: DHExp.t(list(Id.t)),
+      d: DHExp.t(IdTag.t),
     )
     : Node.t => {
   DHDoc_Exp.mk(
diff --git a/src/haz3lweb/view/dhcode/layout/DHDoc_Exp.re b/src/haz3lweb/view/dhcode/layout/DHDoc_Exp.re
index dd08c99475..9b0a08a773 100644
--- a/src/haz3lweb/view/dhcode/layout/DHDoc_Exp.re
+++ b/src/haz3lweb/view/dhcode/layout/DHDoc_Exp.re
@@ -42,7 +42,7 @@ let precedence_bin_string_op = (bso: Operators.op_bin_string) =>
   | Concat => DHDoc_common.precedence_Plus
   | Equals => DHDoc_common.precedence_Equals
   };
-let rec precedence = (~show_casts: bool, d: DHExp.t(list(Id.t))) => {
+let rec precedence = (~show_casts: bool, d: DHExp.t(IdTag.t)) => {
   let precedence' = precedence(~show_casts);
   switch (DHExp.term_of(d)) {
   | Var(_)
@@ -114,13 +114,13 @@ let mk =
       ~next_steps: list((int, Id.t)), // The options for the next step, if it hasn't been chosen yet
       ~env: ClosureEnvironment.t,
       ~infomap: Statics.Map.t,
-      d: DHExp.t(list(Id.t)),
+      d: DHExp.t(IdTag.t),
     )
     : DHDoc.t => {
   let precedence = precedence(~show_casts=settings.show_casts);
   let rec go =
           (
-            d: DHExp.t(list(Id.t)),
+            d: DHExp.t(IdTag.t),
             env: ClosureEnvironment.t,
             enforce_inline: bool,
             recent_subst: list(Var.t),
diff --git a/src/haz3lweb/view/dhcode/layout/DHDoc_Pat.re b/src/haz3lweb/view/dhcode/layout/DHDoc_Pat.re
index 8996bd4b03..c08ab11e5c 100644
--- a/src/haz3lweb/view/dhcode/layout/DHDoc_Pat.re
+++ b/src/haz3lweb/view/dhcode/layout/DHDoc_Pat.re
@@ -1,7 +1,7 @@
 open Pretty;
 open Haz3lcore;
 
-let precedence = (dp: Pat.t) =>
+let precedence = (dp: Pat.t(IdTag.t)) =>
   switch (DHPat.term_of(dp)) {
   | EmptyHole
   | MultiHole(_)
@@ -27,7 +27,7 @@ let rec mk =
           ~parenthesize=false,
           ~show_casts,
           ~enforce_inline: bool,
-          dp: Pat.t,
+          dp: Pat.t(IdTag.t),
         )
         : DHDoc.t => {
   let mk' = mk(~enforce_inline, ~infomap, ~show_casts);
diff --git a/src/haz3lweb/view/dhcode/layout/DHDoc_Typ.re b/src/haz3lweb/view/dhcode/layout/DHDoc_Typ.re
index 143e36d3e3..73e54b8c2c 100644
--- a/src/haz3lweb/view/dhcode/layout/DHDoc_Typ.re
+++ b/src/haz3lweb/view/dhcode/layout/DHDoc_Typ.re
@@ -8,5 +8,5 @@ let promote_annot =
   | HTypAnnot.HoleLabel => DHAnnot.HoleLabel
   | HTypAnnot.Delim => DHAnnot.Delim;
 let promote = (d: HTypDoc.t): DHDoc.t => d |> Doc.map_annot(promote_annot);
-let mk = (~enforce_inline: bool, ty: Typ.t): DHDoc.t =>
+let mk = (~enforce_inline: bool, ty: Typ.t(IdTag.t)): DHDoc.t =>
   ty |> HTypDoc.mk(~enforce_inline) |> promote;
diff --git a/src/haz3lweb/view/dhcode/layout/HTypDoc.re b/src/haz3lweb/view/dhcode/layout/HTypDoc.re
index 996d01f607..f616e7f9c2 100644
--- a/src/haz3lweb/view/dhcode/layout/HTypDoc.re
+++ b/src/haz3lweb/view/dhcode/layout/HTypDoc.re
@@ -12,7 +12,7 @@ let precedence_Sum = 3;
 let precedence_Ap = 4;
 let precedence_Const = 5;
 
-let precedence = (ty: Typ.t): int =>
+let precedence = (ty: Typ.t(IdTag.t)): int =>
   switch (Typ.term_of(ty)) {
   | Int
   | Float
@@ -51,7 +51,8 @@ let pad_child =
 
 let mk_delim = s => Doc.(annot(HTypAnnot.Delim, text(s)));
 
-let rec mk = (~parenthesize=false, ~enforce_inline: bool, ty: Typ.t): t => {
+let rec mk =
+        (~parenthesize=false, ~enforce_inline: bool, ty: Typ.t(IdTag.t)): t => {
   open Doc;
   let mk' = mk(~enforce_inline);
   let mk_right_associative_operands = (precedence_op, ty1, ty2) => (
diff --git a/src/haz3lweb/view/dhcode/layout/HTypDoc.rei b/src/haz3lweb/view/dhcode/layout/HTypDoc.rei
index ab07b0e81e..2253bed749 100644
--- a/src/haz3lweb/view/dhcode/layout/HTypDoc.rei
+++ b/src/haz3lweb/view/dhcode/layout/HTypDoc.rei
@@ -2,4 +2,4 @@ open Haz3lcore;
 
 type t = Pretty.Doc.t(HTypAnnot.t);
 
-let mk: (~parenthesize: bool=?, ~enforce_inline: bool, Typ.t) => t;
+let mk: (~parenthesize: bool=?, ~enforce_inline: bool, Typ.t(IdTag.t)) => t;