global and local variables with scope

also reworked arg parsing, now has --debug flag

lib/stmt.ml

@@ -1,13 +1,44 @@
-type stmt = Expr of Expr.expr_node | Print of Expr.expr_node
+open Expr
+
+type stmt =
+  | Expr of expr_node
+  | Print of expr_node
+  | VarDecl of { name : string; init : expr_node option }
+  | Block of stmt_node list
+
 and stmt_node = { stmt : stmt; pos : Error.code_pos }
 
-let show_stmt stmt =
-  match stmt with Expr expr -> Expr.show_expr expr.expr | Print expr -> Expr.show_expr expr.expr
+let rec show_stmt ?(indent = 0) stmt =
+  let indent_s = String.make indent ' ' in
+  match stmt with
+  | Expr expr -> indent_s ^ "Expr\n" ^ show_expr ~indent:(indent + 2) expr.expr
+  | Print expr -> indent_s ^ "Print\n" ^ show_expr ~indent:(indent + 2) expr.expr
+  | VarDecl { name; init } -> (
+      indent_s ^ "Var " ^ name
+      ^
+      match init with Some init -> " = \n" ^ show_expr ~indent:(indent + 2) init.expr | None -> "")
+  | Block stmts ->
+      let stmts_s =
+        List.fold_left
+          (fun acc stmt -> acc ^ show_stmt ~indent:(indent + 2) stmt.stmt ^ "\n")
+          "" stmts
+      in
+      "Block" ^ stmts_s ^ "End"
 
-let make_expr_stmt (pos : Error.code_pos) (expr : Expr.expr_node) : stmt_node =
+let show_stmt_node stmt_node = show_stmt stmt_node.stmt
+
+let make_expr_stmt (pos : Error.code_pos) (expr : expr_node) : stmt_node =
   let stmt = Expr expr in
   { stmt; pos }
 
-let make_print (pos : Error.code_pos) (expr : Expr.expr_node) : stmt_node =
+let make_print (pos : Error.code_pos) (expr : expr_node) : stmt_node =
   let stmt = Print expr in
   { stmt; pos }
+
+let make_var_decl (pos : Error.code_pos) (name : string) (init : expr_node option) =
+  let stmt = VarDecl { name; init } in
+  { stmt; pos }
+
+let make_block (pos : Error.code_pos) (stmts : stmt_node list) : stmt_node =
+  let stmt = Block stmts in
+  { stmt; pos }