Make local declarations require "var" prefix

debug/app.ona

@@ -1,5 +1,5 @@
 
-i = 0
+var i = 0
 
 while i < 5:
 	@print("hello, world")

source/ona/kym.zig

@@ -213,16 +213,11 @@ pub const RuntimeEnv = struct {
 					.local_set => |local_set| {
 						try self.compile_expression(chunk, local_set.value_expression.*);
 
-						if (self.resolve_local(local_set.identifier)) |index| {
-							try chunk.opcodes.push_one(.{.local_set = index});
-						} else {
-							if (self.local_identifiers_count == self.local_identifiers_buffer.len) {
-								return chunk.env.raise(error.BadSyntax, "chunks may have a maximum of 255 locals");
-							}
-
-							self.local_identifiers_buffer[self.local_identifiers_count] = local_set.identifier;
-							self.local_identifiers_count += 1;
-						}
+						try chunk.opcodes.push_one(.{
+							.local_set = self.resolve_local(local_set.identifier) orelse {
+								return chunk.env.raise(error.BadSyntax, "undefined local");
+							},
+						});
 					},
 
 					.field_get => |field_get| {
@@ -271,6 +266,17 @@ pub const RuntimeEnv = struct {
 						}
 					},
 
+					.local_var => |local_var| {
+						try self.compile_expression(chunk, local_var.assigned_expression);
+
+						if (self.local_identifiers_count == self.local_identifiers_buffer.len) {
+							return chunk.env.raise(error.BadSyntax, "chunks may have a maximum of 255 locals");
+						}
+
+						self.local_identifiers_buffer[self.local_identifiers_count] = local_var.identifier;
+						self.local_identifiers_count += 1;
+					},
+
 					.block => |block| {
 						for (block.values) |block_statement| {
 							try self.compile_statement(chunk, block_statement);

source/ona/kym/ast.zig

@@ -139,6 +139,11 @@ pub const ParseError = error {
 pub const Statement = union (enum) {
 	@"return": ?Expression,
 
+	local_var: struct {
+		identifier: []const coral.io.Byte,
+		assigned_expression: Expression,
+	},
+
 	@"if": struct {
 		condition_expression: Expression,
 		block_statements: List,
@@ -650,6 +655,30 @@ pub const Tree = struct {
 				};
 			},
 
+			.keyword_var => {
+				self.tokenizer.skip_newlines();
+
+				const identifier = switch (self.tokenizer.token) {
+					.identifier => |identifier| identifier,
+					else => return self.report("expected identifier after `var` declaration statement"),
+				};
+
+				self.tokenizer.skip_newlines();
+
+				if (self.tokenizer.token != .symbol_equals) {
+					return self.report("expected `=` after declaration identifier");
+				}
+
+				self.tokenizer.skip_newlines();
+
+				return .{
+					.local_var = .{
+						.assigned_expression = try self.parse_expression(),
+						.identifier = identifier,
+					},
+				};
+			},
+
 			.keyword_if => return self.parse_branch(),
 			else => return .{.expression = try self.parse_expression()},
 		}

source/ona/kym/tokens.zig

@@ -44,6 +44,7 @@ pub const Token = union(enum) {
 	keyword_while,
 	keyword_else,
 	keyword_elif,
+	keyword_var,
 
 	pub fn text(self: Token) []const coral.io.Byte {
 		return switch (self) {
@@ -91,6 +92,7 @@ pub const Token = union(enum) {
 			.keyword_while => "while",
 			.keyword_elif => "elif",
 			.keyword_else => "else",
+			.keyword_var => "var",
 		};
 	}
 };
@@ -261,6 +263,14 @@ pub const Tokenizer = struct {
 							}
 						},
 
+						'v' => {
+							if (coral.io.ends_with(identifier, "ar")) {
+								self.token = .keyword_var;
+
+								return;
+							}
+						},
+
 						'w' => {
 							if (coral.io.ends_with(identifier, "hile")) {
 								self.token = .keyword_while;