diff --git a/lib/error.ml b/lib/error.ml
index adb6703..2ac35d5 100644
--- a/lib/error.ml
+++ b/lib/error.ml
@@ -4,9 +4,9 @@ type lexer_error = { pos : code_pos; msg : string }
 module LexerError = struct
   type t = lexer_error
 
-  let make (pos : code_pos) (msg : string) : lexer_error = { pos; msg }
+  let make (pos : code_pos) (msg : string) : t = { pos; msg }
 
-  let show (e : lexer_error) =
+  let show (e : t) =
     Printf.sprintf "LexerError at line %d, column %d: %s" e.pos.line e.pos.col e.msg
 end
 
@@ -15,27 +15,22 @@ type parser_error = { pos : code_pos; msg : string }
 module ParserError = struct
   type t = parser_error
 
-  let make (pos : code_pos) (msg : string) : parser_error = { pos; msg }
+  let make (pos : code_pos) (msg : string) : t = { pos; msg }
 
-  let show (e : parser_error) =
+  let show (e : t) =
     Printf.sprintf "ParserError at line %d, column %d: %s" e.pos.line e.pos.col e.msg
 end
 
 (* type runtime_error = { pos : code_pos; msg : string; type_ : runtime_error_type } *)
-type runtime_error = Error of { pos : code_pos; msg : string } | Break | Continue
+type runtime_error = { pos : code_pos; msg : string }
 
 module RuntimeError = struct
-  type t = parser_error
+  type t = runtime_error
 
-  let make (pos : code_pos) (msg : string) : runtime_error = Error { pos; msg }
-  let break () : runtime_error = Break
-  let continue () : runtime_error = Continue
+  let make (pos : code_pos) (msg : string) : t = { pos; msg }
 
-  let show (e : runtime_error) =
-    match e with
-    | Error { pos; msg } ->
-        Printf.sprintf "RuntimeError at line %d, column %d: %s" pos.line pos.col msg
-    | Break | Continue -> assert false
+  let show ({ pos; msg } : t) =
+    Printf.sprintf "RuntimeError at line %d, column %d: %s" pos.line pos.col msg
 end
 
 type lox_error =
diff --git a/lib/interpreter.ml b/lib/interpreter.ml
index 54b7912..581086c 100644
--- a/lib/interpreter.ml
+++ b/lib/interpreter.ml
@@ -1,5 +1,3 @@
-let ( let* ) = Result.bind
-
 open Environment
 open Error
 open Expr
@@ -9,22 +7,69 @@ open Value
 let value_of_literal (literal : literal) : Value.lox_value =
   match literal with String s -> String s | Number x -> Number x | Bool b -> Bool b | Nil -> Nil
 
-let rec interpret_expr (env : environment) (expr_node : expr_node) :
-    (lox_value, runtime_error) result =
+type 'a interpreter_result =
+  | Ok of 'a
+  | Break
+  | Continue
+  | Return of lox_value
+  | Error of runtime_error
+
+module InterpreterResult = struct
+  type 'a t = 'a interpreter_result
+
+  let ok value = Ok value
+  let break () = Break
+  let continue () = Continue
+  let return (value : lox_value) = Return value
+  let error e = Error e
+
+  let map f result =
+    match result with
+    | Ok x -> f x |> ok
+    | Break -> Break
+    | Continue -> Continue
+    | Return _ as r -> r
+    | Error _ as e -> e
+
+  let map_error f result =
+    match result with
+    | Error e -> f e |> error
+    | Ok _ as x -> x
+    | Break -> Break
+    | Continue -> Continue
+    | Return _ as r -> r
+
+  let bind result f =
+    match result with
+    | Ok value -> f value
+    | Break -> Break
+    | Continue -> Continue
+    | Return _ as r -> r
+    | Error _ as e -> e
+end
+
+open InterpreterResult
+
+let ( let* ) = InterpreterResult.bind
+
+type expr_result = lox_value interpreter_result
+type stmt_result = unit interpreter_result
+
+let rec interpret_expr (env : environment) (expr_node : expr_node) : lox_value interpreter_result =
   let { pos; expr } = expr_node in
   match expr with
-  | Literal literal -> value_of_literal literal |> Result.ok
+  | Literal literal -> value_of_literal literal |> ok
   | Variable name -> (
       let value_opt = Env.get env name in
       match value_opt with
       | Some x -> Ok x
       | None ->
           let msg = Printf.sprintf "name \"%s\" is not defined" name in
-          RuntimeError.make pos msg |> Result.error)
+          RuntimeError.make pos msg |> error)
   | Assignment { name; expr } ->
       if not (Env.is_defined env name) then
         let msg = Printf.sprintf "tried to assign to undefined variable %s" name in
-        RuntimeError.make pos msg |> Result.error
+        RuntimeError.make pos msg |> error
       else
         let* value = interpret_expr env expr in
         Env.update env name value;
@@ -32,44 +77,44 @@ let rec interpret_expr (env : environment) (expr_node : expr_node) :
   | Unary { op; expr } -> (
       let* expr = interpret_expr env expr in
       match (op, expr) with
-      | Neg, Number x -> Number (-.x) |> Result.ok
-      | Not, value -> Bool (lox_value_to_bool value |> not) |> Result.ok
+      | Neg, Number x -> Number (-.x) |> ok
+      | Not, value -> Bool (lox_value_to_bool value |> not) |> ok
       | _, _ ->
           let msg =
             Printf.sprintf "Invalid operant of type %s to operator %s"
               (type_string_of_lox_value expr) (show_unary_op op)
           in
-          RuntimeError.make pos msg |> Result.error)
+          RuntimeError.make pos msg |> error)
   | Binary { op; left; right } -> (
       let* left = interpret_expr env left in
       let* right = interpret_expr env right in
       match (left, op, right) with
-      | String a, Plus, String b -> String (a ^ b) |> Result.ok
-      | Number x, Plus, Number y -> Number (x +. y) |> Result.ok
-      | Number x, Minus, Number y -> Number (x -. y) |> Result.ok
-      | Number x, Mul, Number y -> Number (x *. y) |> Result.ok
+      | String a, Plus, String b -> String (a ^ b) |> ok
+      | Number x, Plus, Number y -> Number (x +. y) |> ok
+      | Number x, Minus, Number y -> Number (x -. y) |> ok
+      | Number x, Mul, Number y -> Number (x *. y) |> ok
       | Number x, Div, Number y ->
-          if y <> 0. then Number (x /. y) |> Result.ok
+          if y <> 0. then Number (x /. y) |> ok
           else
             let msg = "Division by 0" in
-            RuntimeError.make pos msg |> Result.error
-      | Bool b, And, Bool c -> Bool (b && c) |> Result.ok
-      | Bool b, Or, Bool c -> Bool (b || c) |> Result.ok
+            RuntimeError.make pos msg |> error
+      | Bool b, And, Bool c -> Bool (b && c) |> ok
+      | Bool b, Or, Bool c -> Bool (b || c) |> ok
       | _, Equal, _ -> Ok (Bool (left = right))
-      | Number x, Greater, Number y -> Bool (x > y) |> Result.ok
-      | Number x, GreaterEqual, Number y -> Bool (x >= y) |> Result.ok
-      | Number x, Less, Number y -> Bool (x < y) |> Result.ok
-      | Number x, LessEqual, Number y -> Bool (x <= y) |> Result.ok
-      | String a, Greater, String b -> Bool (a > b) |> Result.ok
-      | String a, GreaterEqual, String b -> Bool (a >= b) |> Result.ok
-      | String a, Less, String b -> Bool (a < b) |> Result.ok
-      | String a, LessEqual, String b -> Bool (a <= b) |> Result.ok
+      | Number x, Greater, Number y -> Bool (x > y) |> ok
+      | Number x, GreaterEqual, Number y -> Bool (x >= y) |> ok
+      | Number x, Less, Number y -> Bool (x < y) |> ok
+      | Number x, LessEqual, Number y -> Bool (x <= y) |> ok
+      | String a, Greater, String b -> Bool (a > b) |> ok
+      | String a, GreaterEqual, String b -> Bool (a >= b) |> ok
+      | String a, Less, String b -> Bool (a < b) |> ok
+      | String a, LessEqual, String b -> Bool (a <= b) |> ok
       | _, _, _ ->
           let msg =
             Printf.sprintf "Invalid operands of type %s and %s to operator %s"
               (type_string_of_lox_value left) (type_string_of_lox_value right) (show_binary_op op)
           in
-          RuntimeError.make pos msg |> Result.error)
+          RuntimeError.make pos msg |> error)
   | Logical { op; left; right } -> (
       let* left = interpret_expr env left in
       match (op, lox_value_to_bool left) with
@@ -77,56 +122,60 @@ let rec interpret_expr (env : environment) (expr_node : expr_node) :
       | _ -> interpret_expr env right)
   | Call { callee; args } -> (
       let* callee = interpret_expr env callee in
-      let f (acc : (lox_value list, runtime_error) result) (arg : expr_node) :
-          (lox_value list, runtime_error) result =
-        match acc with
-        | Ok acc ->
-            let* arg = interpret_expr env arg in
-            Ok (arg :: acc)
-        | Error e -> Error e
+      let f (acc : lox_value list interpreter_result) arg =
+        let* acc = acc in
+        let* arg = interpret_expr env arg in
+        Ok (arg :: acc)
       in
       let* args = List.fold_left f (Ok []) args in
       let args = List.rev args in
       match callee with
-      | Function (NativeFunction { name; arity; fn }) ->
+      | NativeFunction { name; arity; fn } -> (
           let args_len = List.length args in
           if args_len <> arity then
             let msg =
               Printf.sprintf "Native Function %s has arity %d, but was called with %d args" name
                 args_len arity
             in
-            RuntimeError.make pos msg |> Result.error
-          else fn args |> Result.map_error (RuntimeError.make pos)
-      | Function (LoxFunction { name; arity; arg_names; body }) ->
+            RuntimeError.make pos msg |> error
+          else
+            match fn args with Ok value -> Ok value | Error s -> RuntimeError.make pos s |> error)
+      | Function { name; arity; arg_names; body } -> (
           let args_len = List.length args in
           if args_len <> arity then
             let msg =
               Printf.sprintf "Function %s has arity %d, but was called with %d args" name args_len
                 arity
             in
-            RuntimeError.make pos msg |> Result.error
+            RuntimeError.make pos msg |> error
           else
             let env = Env.push_frame env in
             let () =
               List.iter2 (fun name value -> assert (Env.define env name value)) arg_names args
             in
-            let* () = interpret_stmt env body in
-            Ok Nil
+            let result = interpret_stmt env body in
+            match result with
+            | Ok () -> Ok Nil
+            | Return value -> Ok value
+            | Error _ as e -> e
+            | _ -> assert false)
       | _ ->
           ignore args;
           let msg = Printf.sprintf "%s object is not callable" (type_string_of_lox_value callee) in
-          RuntimeError.make pos msg |> Result.error)
+          RuntimeError.make pos msg |> error)
 
-and interpret_stmt (env : environment) (stmt_node : stmt_node) : (unit, runtime_error) result =
-  let { pos; stmt } = stmt_node in
-  ignore pos;
+and interpret_stmt (env : environment) (stmt_node : stmt_node) : unit interpreter_result =
+  let { stmt; pos } = stmt_node in
   match stmt with
   | Expr expr ->
       let* value = interpret_expr env expr in
       ignore value;
       Ok ()
-  | Break -> RuntimeError.break () |> Result.error
-  | Continue -> RuntimeError.continue () |> Result.error
+  | Break -> break ()
+  | Continue -> continue ()
+  | Return expr ->
+      let* value = interpret_expr env expr in
+      Return value
   | Print expr ->
       let* value = interpret_expr env expr in
       print_endline (Value.string_of_lox_value value);
@@ -139,7 +188,7 @@ and interpret_stmt (env : environment) (stmt_node : stmt_node) : (unit, runtime_
         let msg =
           Printf.sprintf "Tried to define %s, but a variable of that name was already defined" name
         in
-        RuntimeError.make pos msg |> Result.error
+        RuntimeError.make pos msg |> error
   | FunDecl { name; arg_names; body } ->
       let fn = make_lox_function name arg_names body in
       let success = Env.define env name fn in
@@ -149,7 +198,7 @@ and interpret_stmt (env : environment) (stmt_node : stmt_node) : (unit, runtime_
           Printf.sprintf
             "Tried to define function %s, but a variable of that name was already defined" name
         in
-        RuntimeError.make pos msg |> Result.error
+        RuntimeError.make pos msg |> error
   | Block stmts ->
       let env = Env.enter env in
       let rec _interpret stmts =
@@ -171,9 +220,9 @@ and interpret_stmt (env : environment) (stmt_node : stmt_node) : (unit, runtime_
       if cond then
         let result = interpret_stmt env body in
         match result with
-        | Ok () | Error Continue -> interpret_stmt env stmt_node
-        | Error Break -> Ok ()
-        | Error e -> Error e
+        | Ok () | Continue -> interpret_stmt env stmt_node
+        | Break -> Ok ()
+        | other -> other
       else Ok ()
   | For { init; cond; update; body } ->
       let env = Env.enter env in
@@ -182,7 +231,7 @@ and interpret_stmt (env : environment) (stmt_node : stmt_node) : (unit, runtime_
         cond
         |> Option.map (interpret_expr env)
         |> Option.value ~default:(Ok (Value.Bool true))
-        |> Result.map Value.lox_value_to_bool
+        |> map Value.lox_value_to_bool
       in
       let do_update () =
         update |> Option.map (interpret_expr env) |> Option.value ~default:(Ok Value.Nil)
@@ -192,12 +241,12 @@ and interpret_stmt (env : environment) (stmt_node : stmt_node) : (unit, runtime_
         if cond then
           let result = interpret_stmt env body in
           match result with
-          | Ok () | Error Continue ->
+          | Ok () | Continue ->
               let* value = do_update () in
               ignore value;
               loop ()
-          | Error Break -> Ok ()
-          | Error e -> Error e
+          | Break -> Ok ()
+          | other -> other
         else Ok ()
       in
       loop ()
diff --git a/lib/lox.ml b/lib/lox.ml
index 5d88c74..93a5c7b 100644
--- a/lib/lox.ml
+++ b/lib/lox.ml
@@ -49,9 +49,11 @@ let run ?(env : Environment.environment option) ?(debug = false) (source : strin
   let rec interpret_stmts (stmts : Stmt.stmt_node list) =
     match stmts with
     | [] -> Ok ()
-    | stmt :: tail ->
-        let* () = Interpreter.interpret_stmt env stmt in
-        interpret_stmts tail
+    | stmt :: tail -> (
+        match Interpreter.interpret_stmt env stmt with
+        | Ok () -> interpret_stmts tail
+        | Error e -> Error e
+        | _ -> assert false)
   in
   interpret_stmts stmts |> Error.of_runtimer_error
 
diff --git a/lib/loxstd.ml b/lib/loxstd.ml
index b35f4bf..d981164 100644
--- a/lib/loxstd.ml
+++ b/lib/loxstd.ml
@@ -23,6 +23,6 @@ let exit : native_function =
   { name = "exit"; arity = 1; fn }
 
 let init_std (env : environment) =
-  let register_fn fn = Env.define_global env fn.name (Function (NativeFunction fn)) in
+  let register_fn fn = Env.define_global env fn.name (NativeFunction fn) in
   let _ = List.map register_fn [ clock; exit ] in
   ()
diff --git a/lib/stmt.ml b/lib/stmt.ml
index 14b3fcd..d10fbc3 100644
--- a/lib/stmt.ml
+++ b/lib/stmt.ml
@@ -5,6 +5,7 @@ type stmt =
   | Expr of expr_node
   | Break
   | Continue
+  | Return of expr_node
   | Print of expr_node
   | VarDecl of { name : string; init : expr_node option }
   | FunDecl of { name : string; arg_names : string list; body : stmt_node }
@@ -28,6 +29,9 @@ let rec show_stmt ?(indent = 0) stmt =
   | Expr expr -> indent_s ^ "Expr\n" ^ show_expr_ind expr.expr
   | Break -> indent_s ^ "Break"
   | Continue -> indent_s ^ "Continue"
+  | Return expr ->
+      let expr_s = show_expr_ind expr.expr in
+      "Return\n" ^ expr_s
   | Print expr -> indent_s ^ "Print\n" ^ show_expr_ind expr.expr
   | VarDecl { name; init } ->
       let init_s = match init with Some init -> " = \n" ^ show_expr_ind init.expr | None -> "" in
@@ -90,6 +94,7 @@ let make_stmt_node (pos : code_pos) (stmt : stmt) : stmt_node = { stmt; pos }
 let make_expr_stmt (pos : code_pos) (expr : expr_node) : stmt_node = Expr expr |> make_stmt_node pos
 let make_break (pos : code_pos) : stmt_node = Break |> make_stmt_node pos
 let make_continue (pos : code_pos) : stmt_node = Continue |> make_stmt_node pos
+let make_return (pos : code_pos) (expr : expr_node) = Return expr |> make_stmt_node pos
 let make_print (pos : code_pos) (expr : expr_node) : stmt_node = Print expr |> make_stmt_node pos
 
 let make_var_decl (pos : code_pos) (name : string) (init : expr_node option) =
diff --git a/lib/value.ml b/lib/value.ml
index e55f588..b4cf40d 100644
--- a/lib/value.ml
+++ b/lib/value.ml
@@ -1,6 +1,7 @@
 type lox_function = {
   name : string;
   arity : int;
+  (* env : Environment.environment; *)
   arg_names : string list;
   body : Stmt.stmt_node; [@printer fun fmt _ -> fprintf fmt "<body>"]
 }
@@ -13,16 +14,19 @@ type native_function = {
 }
 [@@deriving show { with_path = false }]
 
-and function_ = NativeFunction of native_function | LoxFunction of lox_function
-[@@deriving show { with_path = false }]
-
-and lox_value = Function of function_ | String of string | Number of float | Bool of bool | Nil
+and lox_value =
+  | Function of lox_function
+  | NativeFunction of native_function
+  | String of string
+  | Number of float
+  | Bool of bool
+  | Nil
 [@@deriving show { with_path = false }]
 
 let string_of_lox_value lox_value =
   match lox_value with
-  | Function (NativeFunction { name; arity; _ }) -> Printf.sprintf "<native fn %s/%d>" name arity
-  | Function (LoxFunction { name; arity; _ }) -> Printf.sprintf "<fn %s/%d>" name arity
+  | Function { name; arity; _ } -> Printf.sprintf "<fn %s/%d>" name arity
+  | NativeFunction { name; arity; _ } -> Printf.sprintf "<native fn %s/%d>" name arity
   | String s -> s
   | Number x -> if Float.is_integer x then string_of_int (Int.of_float x) else string_of_float x
   | Bool b -> string_of_bool b
@@ -30,8 +34,8 @@ let string_of_lox_value lox_value =
 
 let type_string_of_lox_value lox_value =
   match lox_value with
-  | Function (NativeFunction _) -> "NativeFunction"
-  | Function (LoxFunction _) -> "Function"
+  | Function _ -> "Function"
+  | NativeFunction _ -> "NativeFunction"
   | String _ -> "String"
   | Number _ -> "Number"
   | Bool _ -> "Bool"
@@ -42,5 +46,4 @@ let lox_value_to_bool lox_value = match lox_value with Bool b -> b | Nil -> fals
 let make_lox_function (name : string) (arg_names : string list) (body : Stmt.stmt_node) : lox_value
     =
   let arity = List.length arg_names in
-  let fn = LoxFunction { name; arity; arg_names; body } in
-  Function fn
+  Function { name; arity; arg_names; body }
diff --git a/lox.t/expressions/evaluate.lox b/lox.t/expressions/evaluate.lox
deleted file mode 100644
index a1d1895..0000000
--- a/lox.t/expressions/evaluate.lox
+++ /dev/null
@@ -1,4 +0,0 @@
-// Note: This is just for the expression evaluating chapter which evaluates an
-// expression directly.
-(5 - (3 - 1)) + -1
-// expect: 2
diff --git a/lox.t/expressions/parse.lox b/lox.t/expressions/parse.lox
deleted file mode 100644
index 0a9e61b..0000000
--- a/lox.t/expressions/parse.lox
+++ /dev/null
@@ -1,3 +0,0 @@
-// Note: This is just for the expression parsing chapter which prints the AST.
-(5 - (3 - 1)) + -1
-// expect: (+ (group (- 5.0 (group (- 3.0 1.0)))) (- 1.0))
diff --git a/lox.t/fib.lox b/lox.t/fib.lox
deleted file mode 100644
index 9e4b114..0000000
--- a/lox.t/fib.lox
+++ /dev/null
@@ -1,6 +0,0 @@
-fun fib(n) {
-  if (n < 2) return n;
-  return fib(n - 2) + fib(n - 1);
-}
-
-print fib(35); // expect: 9227465
diff --git a/lox.t/run.t b/lox.t/run.t
index 0feca4f..f249202 100644
--- a/lox.t/run.t
+++ b/lox.t/run.t
@@ -1,20 +1,7 @@
-$ for lox_file in *.lox **/*.lox; do
->   mlox $lox_file || echo $lox_file failed
-> done
-unexpected_character.lox failed
-string/unterminated.lox failed
-
-
-
 file empty_file.lox
   $ mlox empty_file.lox
 
 
-file fib.lox
-$ mlox fib.lox
-9227465
-
-
 file precedence.lox
   $ mlox precedence.lox
   14
@@ -364,14 +351,6 @@ file continue/while.lox
   9
 
 
-file expressions/evaluate.lox
-$ mlox expressions/evaluate.lox
-
-
-file expressions/parse.lox
-$ mlox expressions/parse.lox
-
-
 file field/call_function_field.lox
 $ mlox field/call_function_field.lox
 
@@ -476,7 +455,8 @@ $ mlox for/return_closure.lox
 
 
 file for/return_inside.lox
-$ mlox for/return_inside.lox
+  $ mlox for/return_inside.lox
+  i
 
 
 file for/scope.lox
@@ -510,7 +490,21 @@ file for/statement_initializer.lox
 
 
 file for/syntax.lox
-$ mlox for/syntax.lox
+  $ mlox for/syntax.lox
+  1
+  2
+  3
+  0
+  1
+  2
+  done
+  0
+  1
+  0
+  1
+  2
+  0
+  1
 
 
 file for/var_in_body.lox
@@ -538,8 +532,9 @@ file function/extra_arguments.lox
 
 
 file function/local_mutual_recursion.lox
-$ mlox function/local_mutual_recursion.lox
-
+  $ mlox function/local_mutual_recursion.lox
+  RuntimeError at line 4, column 11: name "isOdd" is not defined
+  [1]
 
 file function/local_recursion.lox
 $ mlox function/local_recursion.lox
@@ -559,15 +554,27 @@ file function/missing_comma_in_parameters.lox
 
 
 file function/mutual_recursion.lox
-$ mlox function/mutual_recursion.lox
+  $ mlox function/mutual_recursion.lox
+  true
+  true
 
 
 file function/nested_call_with_arguments.lox
-$ mlox function/nested_call_with_arguments.lox
+  $ mlox function/nested_call_with_arguments.lox
+  hello world
 
 
 file function/parameters.lox
-$ mlox function/parameters.lox
+  $ mlox function/parameters.lox
+  0
+  1
+  3
+  6
+  10
+  15
+  21
+  28
+  36
 
 
 file function/print.lox
@@ -577,7 +584,8 @@ file function/print.lox
 
 
 file function/recursion.lox
-$ mlox function/recursion.lox
+  $ mlox function/recursion.lox
+  21
 
 
 file function/too_many_arguments.lox
@@ -1079,23 +1087,29 @@ $ mlox regression/394.lox
 
 
 file return/after_else.lox
-$ mlox return/after_else.lox
+  $ mlox return/after_else.lox
+  ok
 
 
 file return/after_if.lox
-$ mlox return/after_if.lox
+  $ mlox return/after_if.lox
+  ok
 
 
 file return/after_while.lox
-$ mlox return/after_while.lox
+  $ mlox return/after_while.lox
+  ok
 
 
 file return/at_top_level.lox
-$ mlox return/at_top_level.lox
-
+  $ mlox return/at_top_level.lox
+  found 1 ParserError:
+  ParserError at line 1, column 0: Can use return only in functions
+  [1]
 
 file return/in_function.lox
-$ mlox return/in_function.lox
+  $ mlox return/in_function.lox
+  ok
 
 
 file return/in_method.lox
@@ -1103,31 +1117,8 @@ $ mlox return/in_method.lox
 
 
 file return/return_nil_if_no_value.lox
-$ mlox return/return_nil_if_no_value.lox
-
-
-file scanning/identifiers.lox
-$ mlox scanning/identifiers.lox
-
-
-file scanning/keywords.lox
-$ mlox scanning/keywords.lox
-
-
-file scanning/numbers.lox
-$ mlox scanning/numbers.lox
-
-
-file scanning/punctuators.lox
-$ mlox scanning/punctuators.lox
-
-
-file scanning/strings.lox
-$ mlox scanning/strings.lox
-
-
-file scanning/whitespace.lox
-$ mlox scanning/whitespace.lox
+  $ mlox return/return_nil_if_no_value.lox
+  nil
 
 
 file string/error_after_multiline.lox
@@ -1403,7 +1394,8 @@ $ mlox while/return_closure.lox
 
 
 file while/return_inside.lox
-$ mlox while/return_inside.lox
+  $ mlox while/return_inside.lox
+  i
 
 
 file while/syntax.lox
diff --git a/lox.t/scanning/identifiers.lox b/lox.t/scanning/identifiers.lox
deleted file mode 100644
index ef8c098..0000000
--- a/lox.t/scanning/identifiers.lox
+++ /dev/null
@@ -1,12 +0,0 @@
-andy formless fo _ _123 _abc ab123
-abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890_
-
-// expect: IDENTIFIER andy null
-// expect: IDENTIFIER formless null
-// expect: IDENTIFIER fo null
-// expect: IDENTIFIER _ null
-// expect: IDENTIFIER _123 null
-// expect: IDENTIFIER _abc null
-// expect: IDENTIFIER ab123 null
-// expect: IDENTIFIER abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890_ null
-// expect: EOF  null
diff --git a/lox.t/scanning/keywords.lox b/lox.t/scanning/keywords.lox
deleted file mode 100644
index e56d32e..0000000
--- a/lox.t/scanning/keywords.lox
+++ /dev/null
@@ -1,18 +0,0 @@
-and class else false for fun if nil or return super this true var while
-
-// expect: AND and null
-// expect: CLASS class null
-// expect: ELSE else null
-// expect: FALSE false null
-// expect: FOR for null
-// expect: FUN fun null
-// expect: IF if null
-// expect: NIL nil null
-// expect: OR or null
-// expect: RETURN return null
-// expect: SUPER super null
-// expect: THIS this null
-// expect: TRUE true null
-// expect: VAR var null
-// expect: WHILE while null
-// expect: EOF  null
diff --git a/lox.t/scanning/numbers.lox b/lox.t/scanning/numbers.lox
deleted file mode 100644
index 185b5d0..0000000
--- a/lox.t/scanning/numbers.lox
+++ /dev/null
@@ -1,12 +0,0 @@
-123
-123.456
-.456
-123.
-
-// expect: NUMBER 123 123.0
-// expect: NUMBER 123.456 123.456
-// expect: DOT . null
-// expect: NUMBER 456 456.0
-// expect: NUMBER 123 123.0
-// expect: DOT . null
-// expect: EOF  null
diff --git a/lox.t/scanning/punctuators.lox b/lox.t/scanning/punctuators.lox
deleted file mode 100644
index 824ec9a..0000000
--- a/lox.t/scanning/punctuators.lox
+++ /dev/null
@@ -1,21 +0,0 @@
-(){};,+-*!===<=>=!=<>/.
-
-// expect: LEFT_PAREN ( null
-// expect: RIGHT_PAREN ) null
-// expect: LEFT_BRACE { null
-// expect: RIGHT_BRACE } null
-// expect: SEMICOLON ; null
-// expect: COMMA , null
-// expect: PLUS + null
-// expect: MINUS - null
-// expect: STAR * null
-// expect: BANG_EQUAL != null
-// expect: EQUAL_EQUAL == null
-// expect: LESS_EQUAL <= null
-// expect: GREATER_EQUAL >= null
-// expect: BANG_EQUAL != null
-// expect: LESS < null
-// expect: GREATER > null
-// expect: SLASH / null
-// expect: DOT . null
-// expect: EOF  null
diff --git a/lox.t/scanning/strings.lox b/lox.t/scanning/strings.lox
deleted file mode 100644
index 55adfd1..0000000
--- a/lox.t/scanning/strings.lox
+++ /dev/null
@@ -1,6 +0,0 @@
-""
-"string"
-
-// expect: STRING "" 
-// expect: STRING "string" string
-// expect: EOF  null
\ No newline at end of file
diff --git a/lox.t/scanning/whitespace.lox b/lox.t/scanning/whitespace.lox
deleted file mode 100644
index 27ac396..0000000
--- a/lox.t/scanning/whitespace.lox
+++ /dev/null
@@ -1,12 +0,0 @@
-space    tabs				newlines
-
-
-
-
-end
-
-// expect: IDENTIFIER space null
-// expect: IDENTIFIER tabs null
-// expect: IDENTIFIER newlines null
-// expect: IDENTIFIER end null
-// expect: EOF  null