1 files changed, 30 insertions, 3 deletions
diff --git a/src/Contexts.ml b/src/Contexts.ml
index 77dd9c49..1f7d28a4 100644
--- a/src/Contexts.ml
+++ b/src/Contexts.ml
@@ -45,15 +45,42 @@ let fresh_borrow_id (ctx : eval_ctx) : eval_ctx * BorrowId.id =
 let lookup_type_var (ctx : eval_ctx) (vid : TypeVarId.id) : type_var =
   TypeVarId.nth ctx.type_vars vid
 
-let lookup_var (ctx : eval_ctx) (vid : VarId.id) : var =
+let ctx_lookup_var (ctx : eval_ctx) (vid : VarId.id) : var =
   VarId.Map.find vid ctx.vars
 
-let lookup_var_value (ctx : eval_ctx) (vid : VarId.id) : typed_value =
+(** Retrieve a variable's value in an environment *)
+let env_lookup_var_value (env : env) (vid : VarId.id) : typed_value =
   let check_ev (ev : env_value) : typed_value option =
     match ev with
     | Var (vid', v) -> if vid' = vid then Some v else None
     | Abs _ -> None
   in
-  match List.find_map check_ev ctx.env with
+  match List.find_map check_ev env with
   | None -> failwith "Unreachable"
   | Some v -> v
+
+(** Retrieve a variable's value in an evaluation context *)
+let ctx_lookup_var_value (ctx : eval_ctx) (vid : VarId.id) : typed_value =
+  env_lookup_var_value ctx.env vid
+
+(** Update a variable's value in an environment
+
+    This is a helper function: it can break invariants and doesn't perform
+    any check.
+*)
+let env_update_var_value (env : env) (vid : VarId.id) (nv : typed_value) : env =
+  let update_ev (ev : env_value) : env_value =
+    match ev with
+    | Var (vid', v) -> if vid' = vid then Var (vid, nv) else Var (vid', v)
+    | Abs abs -> Abs abs
+  in
+  List.map update_ev env
+
+(** Update a variable's value in an evaluation context.
+
+    This is a helper function: it can break invariants and doesn't perform
+    any check.
+*)
+let ctx_update_var_value (ctx : eval_ctx) (vid : VarId.id) (nv : typed_value) :
+    eval_ctx =
+  { ctx with env = env_update_var_value ctx.env vid nv }