1 files changed, 72 insertions, 0 deletions
diff --git a/src/Substitute.ml b/src/Substitute.ml
new file mode 100644
index 00000000..f8afc4b9
--- /dev/null
+++ b/src/Substitute.ml
@@ -0,0 +1,72 @@
+(** This file implements various substitution utilities to instantiate types,
+    function bodies, etc.
+ *)
+
+module T = Types
+module V = Values
+
+(** Substitute types variables and regions in a type *)
+let rec ty_subst (rsubst : 'r1 -> 'r2) (tsubst : T.TypeVarId.id -> 'r2 T.ty)
+    (ty : 'r1 T.ty) : 'r2 T.ty =
+  let open T in
+  let subst = ty_subst rsubst tsubst in
+  (* helper *)
+  match ty with
+  | Adt (def_id, regions, tys) ->
+      Adt (def_id, List.map rsubst regions, List.map subst tys)
+  | Tuple tys -> Tuple (List.map subst tys)
+  | Bool | Char | Never | Integer _ | Str -> (* no change *) ty
+  | Array aty -> Array (subst aty)
+  | Slice sty -> Slice (subst sty)
+  | Ref (r, ref_ty, ref_kind) -> Ref (rsubst r, subst ref_ty, ref_kind)
+  | Assumed (aty, regions, tys) ->
+      Assumed (aty, List.map rsubst regions, List.map subst tys)
+
+(*(** Works *)
+let ty_subst2 (rsubst : 'r1 -> T.erased_region)
+    (tsubst : T.TypeVarId.id -> T.erased_region T.ty) (ty : 'r1 T.ty) :
+    T.erased_region T.ty =
+  ty_subst rsubst tsubst ty
+
+let ty_subst3 (rsubst : int -> T.erased_region)
+    (tsubst : T.TypeVarId.id -> T.erased_region T.ty) (ty : int T.ty) :
+    T.erased_region T.ty =
+  ty_subst rsubst tsubst ty*)
+
+(*(** Doesn't work *)
+let ty_subst3 (rsubst : T.RegionVarId.id T.region -> T.erased_region)
+    (tsubst : T.TypeVarId.id -> T.erased_region T.ty)
+    (ty : T.RegionVarId.id T.region T.ty) : T.erased_region T.ty =
+  ty_subst2 rsubst tsubst ty*)
+
+(*
+(** Erase the regions in a type and substitute the type variables *)
+let erase_regions_substitute_types
+    (rsubst : T.RegionVarId.id T.region -> T.erased_region)
+    (tsubst : T.TypeVarId.id -> T.erased_region T.ty)
+    (t : T.RegionVarId.id T.region T.ty) =
+  ty_subst rsubst tsubst t*)
+
+(*let erase_regions_substitute_types
+    (rsubst : T.RegionVarId.id T.region -> T.erased_region)
+    (tsubst : T.TypeVarId.id -> T.erased_region T.ty)
+    (ty : T.RegionVarId.id T.region T.ty) : T.erased_region T.ty =
+  ty_subst rsubst tsubst ty*)
+
+(*let erase_regions_substitute_types
+    (tsubst : T.TypeVarId.id -> T.erased_region T.ty)
+    (ty : T.RegionVarId.id T.region T.ty) : T.erased_region T.ty =
+  let rsubst (r : T.RegionVarId.id T.region) : T.erased_region = T.Erased in
+  ty_subst rsubst tsubst ty*)
+
+(*let erase_regions_substitute_types (tsubst : T.TypeVarId.id -> T.ety)
+    (ty : T.rty) : T.ety =
+  let rsubst (r : T.RegionVarId.id T.region) : T.erased_region = T.Erased in
+  ty_subst rsubst tsubst ty*)
+
+(*(** Instantiate the type variables in an ADT definition, and return the list
+    of types of the fields for the chosen variant *)
+let get_adt_instantiated_field_type
+      (def : T.type_def)
+      (opt_variant_id : T.VariantId.id option) (types : T.ety list) :
+      ety list =*)