Make arguments read-only

debug/app.ona

@@ -1,9 +1,7 @@
 
 let printer = lambda (pfx):
-	let prefix = pfx
-
 	return lambda (msg):
-		@print(prefix)
+		@print(pfx)
 		@print(msg)
 	end
 end

source/ona/kym/Chunk.zig

@@ -79,9 +79,7 @@ pub fn dump(chunk: Self, env: *kym.RuntimeEnv) kym.RuntimeError!*kym.RuntimeRef
 
 	const writer = coral.list.stack_as_writer(&buffer);
 
-	_ = coral.utf8.print_string(writer, coral.io.slice_sentineled(@as(coral.io.Byte, 0), try env.unbox_symbol(chunk.name)));
+	_ = coral.utf8.print_string(writer, "\n");
-
-	_ = coral.utf8.print_string(writer, ":\n");
 
 	while (opcode_cursor < chunk.opcodes.values.len) : (opcode_cursor += 1) {
 		_ = coral.utf8.print_formatted(writer, "[{instruction}]: ", .{.instruction = opcode_cursor});
@@ -613,6 +611,12 @@ pub fn make(env: *kym.RuntimeEnv, name: []const coral.io.Byte, environment: *con
 	try compiler.compile_environment(environment);
 
 	if (builtin.mode == .Debug) {
+		const allocation = try coral.utf8.alloc_formatted(env.allocator, "compiled {name}...", .{.name = name});
+
+		defer env.allocator.deallocate(allocation);
+
+		app.log_info(allocation);
+
 		const string_ref = try chunk.dump(env);
 
 		defer env.discard(string_ref);

source/ona/kym/Compiler.zig

@@ -152,7 +152,7 @@ fn compile_expression(self: Self, environment: *const tree.Environment, expressi
 			if (get_capture_index(environment, declaration_get.declaration)) |index| {
 				try self.chunk.opcodes.push_one(.{.push_binding = index});
 
-				if (declaration_get.declaration.is.captured) {
+				if (is_declaration_boxed(declaration_get.declaration)) {
 					try self.chunk.opcodes.push_one(.get_box);
 				}
 
@@ -173,7 +173,7 @@ fn compile_expression(self: Self, environment: *const tree.Environment, expressi
 				try self.chunk.opcodes.push_one(.{.push_binding = index});
 				try self.compile_expression(environment, declaration_set.assign);
 
-				if (declaration_set.declaration.is.captured) {
+				if (is_declaration_boxed(declaration_set.declaration)) {
 					try self.chunk.opcodes.push_one(.set_box);
 				}
 
@@ -359,9 +359,9 @@ pub fn get_capture_index(self: *const tree.Environment, declaration: *const tree
 		while (capture_index < self.capture_count) : (capture_index += 1) {
 			const captured_declaration_index = self.captures[capture_index];
 
-			coral.debug.assert(captured_declaration_index < enclosing_environment.local_declaration_count);
+			coral.debug.assert(captured_declaration_index < enclosing_environment.declaration_count);
 
-			if (&enclosing_environment.local_declarations[captured_declaration_index] == declaration) {
+			if (&enclosing_environment.declarations[captured_declaration_index] == declaration) {
 				return capture_index;
 			}
 		}
@@ -371,15 +371,19 @@ pub fn get_capture_index(self: *const tree.Environment, declaration: *const tree
 }
 
 pub fn get_local_index(self: *const tree.Environment, declaration: *const tree.Declaration) ?u8 {
-	var remaining = self.local_declaration_count;
+	var remaining = self.declaration_count;
 
 	while (remaining != 0) {
 		remaining -= 1;
 
-		if (&self.local_declarations[remaining] == declaration) {
+		if (&self.declarations[remaining] == declaration) {
 			return remaining;
 		}
 	}
 
 	return null;
 }
+
+fn is_declaration_boxed(declaration: *const tree.Declaration) bool {
+	return declaration.is.captured and !declaration.is.readonly;
+}

source/ona/kym/Expr.zig

@@ -419,19 +419,16 @@ fn parse_operand(root: *tree.Root, stream: *tokens.Stream, environment: *tree.En
 		.identifier => |identifier| {
 			stream.skip_newlines();
 
-			const declaration = (try environment.resolve_declaration(identifier)) orelse {
-				return root.report_error(stream, "undefined identifier `{identifier}`", .{
-					.identifier = identifier,
-				});
-			};
-
-			if (declaration.is.argument and declaration.is.captured) {
-				return root.report_error(stream, "arguments cannot be directly captured, create a declaration", .{});
-			}
-
 			return root.create_expr(.{
-				.next = null,
+				.kind = .{
-				.kind = .{.declaration_get = .{.declaration = declaration}},
+					.declaration_get = .{
+						.declaration = (try environment.resolve_declaration(identifier)) orelse {
+							return root.report_error(stream, "undefined identifier `{identifier}`", .{
+								.identifier = identifier,
+							});
+						}
+					},
+				},
 			});
 		},
 
@@ -452,16 +449,9 @@ fn parse_operand(root: *tree.Root, stream: *tokens.Stream, environment: *tree.En
 					else => return root.report_error(stream, "expected identifier", .{}),
 				};
 
-				if (try lambda_environment.declare(.{
+				_ = lambda_environment.declare_argument(identifier) catch |declare_error| {
-					.identifier = identifier,
+					return root.report_declare_error(stream, identifier, declare_error);
-					.is = .{.argument = true},
+				};
-				}) == null) {
-					return root.report_error(stream, "declaration `{identifier}` already exists", .{
-						.identifier = identifier,
-					});
-				}
-
-				lambda_environment.argument_count += 1;
 
 				stream.skip_newlines();
 

source/ona/kym/Stmt.zig

@@ -93,18 +93,13 @@ pub fn parse(root: *tree.Root, stream: *tokens.Stream, environment: *tree.Enviro
 		},
 
 		.keyword_var, .keyword_let => {
-			const storage_token = stream.token;
+			const is_constant = stream.token == .keyword_let;
 
 			stream.skip_newlines();
 
 			const identifier = switch (stream.token) {
 				.identifier => |identifier| identifier,
-
+				else => return root.report_error(stream, "expected identifier after declaration", .{}),
-				else => {
-					return root.report_error(stream, "expected identifier after `{storage}` declaration statement", .{
-						.storage = storage_token.text()
-					});
-				},
 			};
 
 			stream.skip_newlines();
@@ -122,10 +117,30 @@ pub fn parse(root: *tree.Root, stream: *tokens.Stream, environment: *tree.Enviro
 					.declare = .{
 						.initial_expression = try Expr.parse(root, stream, environment),
 
-						.declaration = (try environment.declare(.{.identifier = identifier})) orelse {
+						.declaration = declare: {
-							return root.report_error(stream, "declaration `{identifier}` already exists", .{
+							if (is_constant) {
-								.identifier = identifier,
+								break: declare environment.declare_constant(identifier) catch |declaration_error| {
-							});
+									return switch (declaration_error) {
+										error.OutOfMemory => error.OutOfMemory,
+
+										error.DeclarationExists =>
+											root.report_error(stream, "declaration `{identifier}` already exists", .{
+												.identifier = identifier,
+											}),
+									};
+								};
+							}
+
+							break: declare environment.declare_variable(identifier) catch |declaration_error| {
+								return switch (declaration_error) {
+									error.OutOfMemory => error.OutOfMemory,
+
+									error.DeclarationExists =>
+										root.report_error(stream, "declaration `{identifier}` already exists", .{
+											.identifier = identifier,
+										}),
+								};
+							};
 						},
 					},
 				},

source/ona/kym/tree.zig

@@ -12,19 +12,22 @@ pub const Declaration = struct {
 	is: packed struct {
 		readonly: bool = false,
 		captured: bool = false,
-		argument: bool = false,
 	} = .{},
 };
 
 pub const Environment = struct {
 	captures: [capture_max]u8 = [_]u8{0} ** capture_max,
 	capture_count: u8 = 0,
-	local_declarations: [declaration_max]Declaration = [_]Declaration{.{.identifier = ""}} ** declaration_max,
+	declarations: [declaration_max]Declaration = [_]Declaration{.{.identifier = ""}} ** declaration_max,
-	local_declaration_count: u8 = 0,
+	declaration_count: u8 = 0,
 	argument_count: u8 = 0,
 	statement: ?*const Stmt = null,
 	enclosing: ?*Environment = null,
 
+	const DeclareError = coral.io.AllocationError || error {
+		DeclarationExists,
+	};
+
 	const capture_max = coral.math.max_int(@typeInfo(u8).Int);
 
 	const declaration_max = coral.math.max_int(@typeInfo(u8).Int);
@@ -35,30 +38,70 @@ pub const Environment = struct {
 		});
 	}
 
-	pub fn declare(self: *Environment, declaration: Declaration) coral.io.AllocationError!?*const Declaration {
+	fn declare(self: *Environment, declaration: Declaration) DeclareError!*const Declaration {
-		if (self.local_declaration_count == self.local_declarations.len) {
+		if (self.declaration_count == self.declarations.len) {
 			return error.OutOfMemory;
 		}
 
-		const declaration_slot = &self.local_declarations[self.local_declaration_count];
+		{
+			var environment = self;
+
+			while (true) {
+				var remaining_count = environment.declaration_count;
+
+				while (remaining_count != 0) {
+					remaining_count -= 1;
+
+					if (coral.io.are_equal(environment.declarations[remaining_count].identifier, declaration.identifier)) {
+						return error.DeclarationExists;
+					}
+				}
+
+				environment = environment.enclosing orelse break;
+			}
+		}
+
+		const declaration_slot = &self.declarations[self.declaration_count];
 
 		declaration_slot.* = declaration;
-		self.local_declaration_count += 1;
+		self.declaration_count += 1;
 
 		return declaration_slot;
 	}
 
+	pub fn declare_argument(self: *Environment, identifier: []const coral.io.Byte) DeclareError!*const Declaration {
+		coral.debug.assert(self.declaration_count <= self.argument_count);
+
+		defer self.argument_count += 1;
+
+		return self.declare(.{
+			.identifier = identifier,
+			.is = .{.readonly = true},
+		});
+	}
+
+	pub fn declare_constant(self: *Environment, identifier: []const coral.io.Byte) DeclareError!*const Declaration {
+		return self.declare(.{
+			.identifier = identifier,
+			.is = .{.readonly = true},
+		});
+	}
+
+	pub fn declare_variable(self: *Environment, identifier: []const coral.io.Byte) DeclareError!*const Declaration {
+		return self.declare(.{.identifier = identifier});
+	}
+
 	pub fn resolve_declaration(self: *Environment, identifier: []const coral.io.Byte) coral.io.AllocationError!?*const Declaration {
 		var environment = self;
 		var ancestry = @as(usize, 0);
 
 		while (true) : (ancestry += 1) {
-			var remaining_count = environment.local_declaration_count;
+			var remaining_count = environment.declaration_count;
 
 			while (remaining_count != 0) {
 				remaining_count -= 1;
 
-				const declaration = &environment.local_declarations[remaining_count];
+				const declaration = &environment.declarations[remaining_count];
 
 				if (coral.io.are_equal(declaration.identifier, identifier)) {
 					if (ancestry != 0) {
@@ -110,6 +153,16 @@ pub const Root = struct {
 		return error.BadSyntax;
 	}
 
+	pub fn report_declare_error(self: *Root, stream: *tokens.Stream, identifier: []const coral.io.Byte, @"error": Environment.DeclareError) ParseError {
+		return switch (@"error") {
+			error.OutOfMemory => error.OutOfMemory,
+
+			error.DeclarationExists => self.report_error(stream, "declaration `{identifier}` already exists", .{
+				.identifier = identifier,
+			}),
+		};
+	}
+
 	pub fn create_expr(self: *Root, expr: Expr) coral.io.AllocationError!*Expr {
 		return coral.io.allocate_one(self.arena.as_allocator(), expr);
 	}