🐛 bug: fma test passes with a hack

So closures are kinda working, but I'm probably missing some edge cases.

src/loader.rs

@@ -251,19 +251,25 @@ pub fn parse_block <R: Read> (rdr: &mut R, blocks: &mut Vec <Block>)
 	}
 	
 	let upvalue_count = parse_int (rdr).unwrap () as usize;
-	
+	let mut upvalues = Vec::with_capacity (upvalue_count);
 	for _ in 0..upvalue_count {
-		// Just ignore these
+		let in_stack = parse_byte (rdr).unwrap () == 1;
+		let idx = parse_byte (rdr).unwrap ();
+		let kind = parse_byte (rdr).unwrap ();
 		
-		for _ in 0..3 {
-			parse_byte (rdr).unwrap ();
-		}
+		let upvalue = crate::state::Upvalue {
+			in_stack,
+			idx,
+			kind,
+		};
+		
+		upvalues.push (upvalue);
 	}
 	
 	blocks.push (Block {
 		constants,
 		instructions,
-		upvalue_count,
+		upvalues,
 	});
 	
 	// Recursion

src/main.rs

@@ -14,12 +14,24 @@ fn main () {
 	let mut list_bytecode = false;
 	let mut pipe_bytecode = false;
 	let mut script = None;
+	let mut breakpoints = vec![];
 	
 	let mut args = std::env::args ();
 	let exe_name = args.next ().unwrap ();
 	
 	while let Some (arg) = args.next () {
 		match arg.as_str () {
+			"--break" => {
+				let s = args.next ().unwrap ();
+				let (block_idx, program_counter) = s.split_once (":").unwrap ();
+				let block_idx = str::parse (block_idx).unwrap ();
+				let program_counter = str::parse (program_counter).unwrap ();
+				
+				breakpoints.push (state::Breakpoint {
+					block_idx,
+					program_counter,
+				});
+			},
 			"--list-bytecode" => list_bytecode = true,
 			"--pipe-bytecode" => pipe_bytecode = true,
 			"--script" => script = Some (args.next ().unwrap ()),
@@ -45,17 +57,63 @@ fn main () {
 		dbg! (&chunk);
 	}
 	
-	let mut vm = State::default ();
-	if std::env::var("LUA_DEBUG").is_ok() {
+	let upvalues = State::upvalues_from_args ([exe_name].into_iter ().chain (args));
+	
+	let mut vm = State::new (&chunk, &upvalues);
+	if std::env::var("LWVM_DEBUG").is_ok() {
 		vm.debug_print = true;
 	}
 	
-	let upvalues = State::upvalues_from_args ([exe_name].into_iter ().chain (args));
+	let max_iters = 2000;
+	let mut in_break = false;
+	let mut last_input = String::new ();
 	
-	vm.breakpoints.push (state::Breakpoint {
-		block_idx: 3,
-		program_counter: 0,
-	});
+	for _ in 0..max_iters {
+		if in_break || breakpoints.iter ().any (|bp| vm.at_breakpoint (bp)) {
+			in_break = true;
+			dbg! (&vm.stack);
 			
-	vm.execute_chunk (&chunk, &upvalues);
+			let mut input = Default::default ();
+			std::io::stdin ().read_line (&mut input).unwrap ();
+			
+			let input = if input == "" {
+				&last_input
+			}
+			else {
+				last_input = input;
+				&last_input
+			};
+			
+			match input.as_str ().trim_end () {
+				"c" => in_break = false,
+				"q" => return,
+				"registers" => {
+					dbg! (&vm.registers);
+					continue;
+				}
+				"s" => {
+					match vm.step () {
+						None => (),
+						Some (state::StepOutput::ChunkReturned (x)) => {
+							dbg! (x);
+							return;
+						},
+					}
+					continue;
+				},
+				x => { dbg! (x); },
+			}
+		}
+		
+		match vm.step () {
+			None => (),
+			Some (state::StepOutput::ChunkReturned (x)) => {
+				dbg! (x);
+				return;
+			},
+		}
+	}
+	
+	dbg! (vm);
+	panic! ("Hit max iterations before block returned");
 }

src/state.rs

@@ -8,11 +8,18 @@ use crate::{
 	},
 };
 
+#[derive (Debug)]
+pub struct Upvalue {
+	pub in_stack: bool,
+	pub idx: u8,
+	pub kind: u8,
+}
+
 #[derive (Debug)]
 pub struct Block {
 	pub instructions: Vec <Instruction>,
 	pub constants: Vec <Value>,
-	pub upvalue_count: usize,
+	pub upvalues: Vec <Upvalue>,
 }
 
 #[derive (Debug)]
@@ -21,7 +28,7 @@ pub struct Chunk {
 }
 
 #[derive (Clone, Debug)]
-struct StackFrame {
+pub struct StackFrame {
 	// i32 makes it a little easier to implement jumps
 	// Starts at 0 right after OP_CALL
 	
@@ -40,34 +47,16 @@ pub struct Breakpoint {
 }
 
 #[derive (Debug)]
-pub struct State {
-	registers: Vec <Value>,
+pub struct State <'a> {
+	pub registers: Vec <Value>,
 	// Currently only used for native function calls
 	top: usize,
-	stack: Vec <StackFrame>,
+	pub stack: Vec <StackFrame>,
 	
 	pub debug_print: bool,
-	pub breakpoints: Vec <Breakpoint>,
 	step_count: u32,
-}
-
-impl Default for State {
-	fn default () -> Self {
-		Self {
-			registers: vec! [Value::Nil; 16],
-			top: 0,
-			stack: vec! [
-				StackFrame {
-					program_counter: 0,
-					block_idx: 0,
-					register_offset: 0,
-				},
-			],
-			debug_print: false,
-			breakpoints: Default::default(),
-			step_count: 0,
-		}
-	}
+	chunk: &'a Chunk,
+	upvalues: &'a [Value],
 }
 
 fn lw_print (l: &mut State) -> i32 {
@@ -86,7 +75,34 @@ fn lw_print (l: &mut State) -> i32 {
 	1
 }
 
-impl State {
+pub enum StepOutput {
+	ChunkReturned (Vec <Value>),
+}
+
+impl <'a> State <'a> {
+	pub fn new (chunk: &'a Chunk, upvalues: &'a [Value]) -> Self {
+		Self {
+			registers: vec! [Value::Nil; 16],
+			top: 0,
+			stack: vec! [
+				StackFrame {
+					program_counter: 0,
+					block_idx: 0,
+					register_offset: 0,
+				},
+			],
+			debug_print: false,
+			step_count: 0,
+			chunk,
+			upvalues,
+		}
+	}
+	
+	pub fn at_breakpoint (&self, bp: &Breakpoint) -> bool {
+		let frame = self.stack.last ().unwrap ();
+		frame.block_idx == bp.block_idx && frame.program_counter == bp.program_counter
+	}
+	
 	pub fn upvalues_from_args <I: Iterator <Item = String>> (args: I) -> Vec <Value>
 	{
 		let arg = args.map (|s| Value::from (s)).enumerate ();
@@ -124,23 +140,13 @@ impl State {
 		self.top - self.stack.last ().unwrap ().register_offset
 	}
 	
-	pub fn execute_chunk (&mut self, chunk: &Chunk, upvalues: &[Value]) 
-	-> Vec <Value> {
-		let max_iters = 2000;
-		
-		for _ in 0..max_iters {
+	pub fn step (&mut self) -> Option <StepOutput> {
+		let chunk = self.chunk;
 		self.step_count += 1;
 		
 		let frame = self.stack.last_mut ().unwrap ().clone ();
 		let block = chunk.blocks.get (frame.block_idx).unwrap ();
 		
-			for bp in &self.breakpoints {
-				if frame.block_idx == bp.block_idx && frame.program_counter == bp.program_counter
-				{
-					dbg! (&self);
-				}
-			}
-			
 		let mut next_pc = frame.program_counter;
 		
 		let pc = usize::try_from (frame.program_counter).expect ("program_counter is not a valid usize");
@@ -160,15 +166,17 @@ impl State {
 				let v_b = self.reg (*b);
 				let v_c = self.reg (*c);
 				
-					let sum = if let (Some (v_b), Some (v_c)) = (v_b.as_int (), v_c.as_int ()) 
+				let x = if let (Some (v_b), Some (v_c)) = (v_b.as_int (), v_c.as_int ()) 
 				{
 					Value::from (v_b + v_c)
 				}
 				else {
-						Value::from (v_b.as_float ().unwrap () + v_c.as_float ().unwrap ())
+					let v_b = v_b.as_float ().unwrap_or_else (|| panic! ("{v_b}"));
+					let v_c = v_c.as_float ().unwrap_or_else (|| panic! ("{v_c}"));
+					Value::from (v_b + v_c)
 				};
 				
-					*self.reg_mut (*a) = sum;
+				*self.reg_mut (*a) = x;
 			},
 			Instruction::Call (a, b, _c) => {
 				let b = usize::from (*b);
@@ -188,7 +196,7 @@ impl State {
 				
 				match v_a {
 					Value::BogusClosure (rc) => {
-							let idx = rc.idx;
+						let idx = rc.borrow ().idx;
 						
 						let block_idx = frame.block_idx;
 						let target_block = idx;
@@ -208,7 +216,7 @@ impl State {
 						}
 						
 						// Skip the PC increment at the bottom of the loop
-							continue;
+						return None;
 					},
 					Value::RsFunc (x) => {
 						let current_frame = self.stack.last ().unwrap ();
@@ -241,10 +249,25 @@ impl State {
 			Instruction::Closure (a, b) => {
 				let b = usize::try_from (*b).unwrap ();
 				
-					*self.reg_mut (*a) = Value::BogusClosure (BogusClosure {
-						idx: b + frame.block_idx + 1,
-						upvalues: vec! [],
-					}.into ());
+				let idx = frame.block_idx + b + 1;
+				let block = &chunk.blocks [idx];
+				
+				let mut new_upvalues = Vec::with_capacity (block.upvalues.len ());
+				for uv in &block.upvalues {
+					let val = if uv.in_stack {
+						self.reg (uv.idx).clone ()
+					}
+					else {
+						// TODO: This isn't really correct
+						self.upvalues [usize::from (uv.idx)].clone ()
+					};
+					new_upvalues.push (val);
+				}
+				
+				*self.reg_mut (*a) = Value::from (BogusClosure {
+					idx,
+					upvalues: new_upvalues,
+				});
 			},
 			Instruction::EqI (a, sb, k_flag) => {
 				if (self.reg (*a).as_int ().unwrap () == *sb as i64) != *k_flag 
@@ -317,7 +340,24 @@ impl State {
 				let b = usize::try_from (*b).unwrap ();
 				let c = usize::try_from (*c).unwrap ();
 				
-					let table = upvalues.get (b).unwrap ().as_table ().expect ("GetTabUp only works on tables").borrow ();
+				// If we're inside a closure, use its upvalues
+				// instead of the chunk's upvalues
+				
+				let frame = self.stack.last ().unwrap ();
+				let value = if frame.register_offset == 0 {
+					self.upvalues.get (b).unwrap ().clone ()
+				}
+				else if let Some (cell) = self.registers [frame.register_offset - 1].as_closure () 
+				{
+					let closure = cell.borrow ();
+					let value = closure.upvalues.get (b).unwrap ();
+					value.clone ()
+				}
+				else {
+					self.upvalues.get (b).unwrap ().clone ()
+				};
+				
+				let table = value.as_table ().expect ("GetTabUp only works on tables").borrow ();
 				
 				let key = match k.get (c).unwrap () {
 					Value::String (s) => String::from (s.as_ref()),
@@ -338,14 +378,21 @@ impl State {
 			},
 			Instruction::GetUpVal (a, b) => {
 				let this_func = self.stack.last ().unwrap ().register_offset - 1;
-					let upvalues = match &self.registers [this_func] {
-						Value::BogusClosure (rc) => &rc.upvalues,
+				let closure = match &self.registers [this_func] {
+					Value::BogusClosure (rc) => rc.clone (),
 					_ => panic! ("Can't do GetUpVal outside a closure"),
 				};
 				
 				let b  = usize::try_from  (*b).unwrap ();
 				
-					*self.reg_mut (*a) = upvalues [b].clone ();
+				let upvalue = match closure.borrow ().upvalues.get (b) {
+					Some (x) => x.clone (),
+					None => {
+						dbg! (chunk, &self);
+						panic! ("Missing upvalue");
+					}
+				};
+				*self.reg_mut (*a) = upvalue;
 			},
 			Instruction::Jmp (s_j) => next_pc += s_j,
 			Instruction::Len (a, b) => {
@@ -397,9 +444,27 @@ impl State {
 				*self.reg_mut (*a) = (b % c).into ();
 			},
 			Instruction::Move (a, b) => {
+				// If the value in b is deleted instead of duplicated,
+				// a bunch of tests fail
+				
 				*self.reg_mut (*a) = self.reg (*b).clone ();
 			},
-				Instruction::Mul (_a, _b, _c) => unimplemented!(),
+			Instruction::Mul (a, b, c) => {
+				let v_b = self.reg (*b);
+				let v_c = self.reg (*c);
+				
+				let x = if let (Some (v_b), Some (v_c)) = (v_b.as_int (), v_c.as_int ()) 
+				{
+					Value::from (v_b * v_c)
+				}
+				else {
+					let v_b = v_b.as_float ().unwrap_or_else (|| panic! ("{v_b}"));
+					let v_c = v_c.as_float ().unwrap_or_else (|| panic! ("{v_c}"));
+					Value::from (v_b * v_c)
+				};
+				
+				*self.reg_mut (*a) = x;
+			},
 			Instruction::NewTable (a) => {
 				*self.reg_mut (*a) = Value::Table (Default::default ());
 			},
@@ -412,24 +477,25 @@ impl State {
 				
 				let popped_frame = self.stack.pop ().unwrap ();
 				
-					// Build closure if needed
-					if *k {
+				// Build closure if needed. No point building if we're
+				// popping the last frame and exiting the program.
 				
+				if *k && ! self.stack.is_empty () {
 					let closure_idx = match &self.registers [popped_frame.register_offset + a] {
-							Value::BogusClosure (rc) => rc.idx,
+						Value::BogusClosure (rc) => rc.borrow ().idx,
 						_ => panic! ("Impossible"),
 					};
 					
-						let upvalue_count = chunk.blocks [closure_idx].upvalue_count;
+					let upvalue_count = chunk.blocks [closure_idx].upvalues.len ();
 					
 					let start_reg = a + popped_frame.register_offset - upvalue_count;
 					
 					let upvalues = self.registers [start_reg..start_reg+upvalue_count].iter ().cloned ().collect ();
 					
-						self.registers [a + popped_frame.register_offset] = Value::BogusClosure (BogusClosure {
+					self.registers [a + popped_frame.register_offset] = Value::from (BogusClosure {
 						idx: closure_idx,
 						upvalues,
-						}.into ());
+					});
 				}
 				
 				if self.debug_print {
@@ -457,10 +523,13 @@ impl State {
 				}
 				else {
 					// Return from the entire program
-						return self.registers [a..(a + b - 1)].to_vec();
+					return Some (StepOutput::ChunkReturned (self.registers [a..(a + b - 1)].to_vec()));
 				}
 			},
-				Instruction::Return0 => unimplemented! (),
+			Instruction::Return0 => {
+				self.stack.pop ();
+				next_pc = self.stack.last ().unwrap ().program_counter;
+			},
 			Instruction::Return1 (a) => {
 				let a = usize::try_from (*a).unwrap ();
 				let popped_frame = self.stack.pop ().unwrap ();
@@ -534,7 +603,36 @@ impl State {
 				}
 			},
 			Instruction::SetTabUp (_a, _b, _c) => unimplemented! (),
-				Instruction::TailCall (_a, _b, _c, _k) => unimplemented! (),
+			Instruction::TailCall (a, b, _c, k) => {
+				assert! (!k, "closing over values in tail calls not implemented");
+				
+				// Shift closure and inputs into place
+				let a = usize::from (*a);
+				let b = usize::from (*b);
+				let offset = frame.register_offset - 1;
+				for i in (offset)..(offset + b) {
+					self.registers [i] = self.registers [i + a + 1].take ();
+				}
+				
+				let value = &self.registers [offset];
+				let closure = if let Some (x) = value.as_closure () {
+					x
+				}
+				else {
+					dbg! (self);
+					panic! ("OP_TAILCALL only implemented for closures");
+				};
+				let closure = closure.borrow ();
+				
+				// Jump into the other function
+				
+				let frame = self.stack.last_mut ().unwrap ();
+				frame.program_counter = 0;
+				frame.block_idx = closure.idx;
+				
+				// Skip the PC increment
+				return None;
+			},
 			Instruction::Test (a, _k) => {
 				if self.reg (*a).is_truthy() {
 					next_pc += 1;
@@ -548,8 +646,26 @@ impl State {
 			let frame = self.stack.last_mut ().unwrap ();
 			frame.program_counter = next_pc;
 		}
+		
+		None
 	}
 	
+	pub fn execute_chunk (&mut self, breakpoints: &[Breakpoint]) 
+	-> Vec <Value> {
+		let max_iters = 2000;
+		
+		for _ in 0..max_iters {
+			if breakpoints.iter ().any (|bp| self.at_breakpoint (bp)) {
+				dbg! (&self);
+			}
+			
+			match self.step () {
+				None => (),
+				Some (StepOutput::ChunkReturned (x)) => return x,
+			}
+		}
+		
+		dbg! (self);
 		panic! ("Hit max iterations before block returned");
 	}
 }

src/tests.rs

@@ -23,9 +23,9 @@ fn calculate_hash<T: Hash>(t: &T) -> u64 {
 /// and returns the output
 
 fn run_chunk (args: &[&str], chunk: &Chunk) -> Vec <Value> {
-	let mut vm = State::default ();
 	let upvalues = State::upvalues_from_args (args.into_iter ().map (|s| s.to_string ()));
-	vm.execute_chunk (chunk, &upvalues)
+	let mut vm = State::new (chunk, &upvalues);
+	vm.execute_chunk (&[])
 }
 
 /// Takes arguments and Lua bytecode, loads it, runs it,
@@ -93,7 +93,7 @@ fn bools () {
 					"arg".into (),
 					"print".into (),
 				],
-				upvalue_count: 1,
+				upvalues: vec! [],
 			},
 			Block {
 				instructions: vec! [
@@ -107,7 +107,7 @@ fn bools () {
 					Inst::Return0,
 				],
 				constants: vec! [],
-				upvalue_count: 0,
+				upvalues: vec! [],
 			},
 		],
 	};
@@ -118,10 +118,9 @@ fn bools () {
 	] {
 		let expected: Vec <Value> = expected;
 		
-		let mut vm = State::default ();
 		let upvalues = State::upvalues_from_args (arg.into_iter ().map (|s| s.to_string ()));
-		
-		let actual = vm.execute_chunk (&chunk, &upvalues);
+		let mut vm = State::new (&chunk, &upvalues);
+		let actual = vm.execute_chunk (&[]);
 		assert_eq! (actual, expected);
 	}
 }
@@ -164,7 +163,7 @@ fn floats () {
 			0.5.into (),
 			"print".into (),
 		],
-		upvalue_count: 1,
+		upvalues: vec! [],
 	};
 	let chunk = Chunk {
 		blocks: vec! [block],
@@ -175,9 +174,9 @@ fn floats () {
 		(vec! ["_exe_name", " "], vec! [3.5.into ()]),
 	] {
 		let expected: Vec <Value> = expected;
-		let mut vm = State::default ();
 		let upvalues = State::upvalues_from_args (arg.into_iter ().map (|s| s.to_string ()));
-		let actual = vm.execute_chunk (&chunk, &upvalues);
+		let mut vm = State::new (&chunk, &upvalues);
+		let actual = vm.execute_chunk (&[]);
 		
 		assert_eq! (actual, expected);
 	}
@@ -185,19 +184,21 @@ fn floats () {
 
 #[test]
 fn fma () {
-	let bytecode = include_bytes! ("../test_vectors/fma.luac");
-	let mut rdr = std::io::Cursor::new (bytecode);
-	let file = crate::loader::parse_chunk (&mut rdr).unwrap ();
-	assert_eq! (file.blocks.len (), 4);
+	let source = include_bytes! ("../test_vectors/fma.lua");
+	let bytecode = &crate::loader::compile_bytecode_from_stdin (source.to_vec ());
+	let chunk = crate::loader::parse_chunk_from_bytes (bytecode).unwrap ();
+	assert_eq! (chunk.blocks.len (), 5);
+	
+	assert_eq! (chunk.blocks [3].upvalues.len (), 2);
 	
 	for (arg, expected) in [
 		(vec! ["_exe_name"], vec! [122.into ()]),
 		(vec! ["_exe_name"], vec! [122.into ()]),
 	] {
 		let expected: Vec <Value> = expected;
-		let mut vm = State::default ();
 		let upvalues = State::upvalues_from_args (arg.into_iter ().map (|s| s.to_string ()));
-		let actual = vm.execute_chunk (&file, &upvalues);
+		let mut vm = State::new (&chunk, &upvalues);
+		let actual = vm.execute_chunk (&[]);
 		
 		assert_eq! (actual, expected);
 	}

src/value.rs

@@ -11,11 +11,12 @@ use std::{
 
 #[derive (Debug, Eq, PartialEq)]
 pub struct BogusClosure {
+	// I'm pretty sure this should be absolute?
 	pub idx: usize,
 	pub upvalues: Vec <Value>,
 }
 
-#[derive (Clone, Debug, PartialEq)]
+#[derive (Clone, PartialEq)]
 pub enum Value {
 	Nil,
 	Boolean (bool),
@@ -32,7 +33,24 @@ pub enum Value {
 	// These are all bogus, I haven't figured out how to implement
 	// closures yet
 	
-	BogusClosure (Rc <BogusClosure>),
+	BogusClosure (Rc <RefCell <BogusClosure>>),
+}
+
+impl fmt::Debug for Value {
+	fn fmt (&self, f: &mut fmt::Formatter) -> fmt::Result {
+		match self {
+			Value::Nil => write! (f, "nil"),
+			Value::Boolean (false) => write! (f, "false"),
+			Value::Boolean (true) => write! (f, "true"),
+			Value::Float (x) => write! (f, "{:?}", x),
+			Value::Integer (x) => write! (f, "{}", x),
+			Value::RsFunc (x) => write! (f, "function: {:?}", x),
+			Value::String (s) => write! (f, "\"{}\"", s),
+			Value::Table (t) => write! (f, "{:?}", t.borrow ()),
+			
+			Value::BogusClosure (x) => write! (f, "{:?}", x.borrow ()),
+		}
+	}
 }
 
 impl Default for Value {
@@ -53,11 +71,17 @@ impl fmt::Display for Value {
 			Value::String (s) => write! (f, "{}", s),
 			Value::Table (t) => write! (f, "table: {:?}", std::rc::Rc::as_ptr (t)),
 			
-			Value::BogusClosure (_) => write! (f, "BogusClosure"),
+			Value::BogusClosure (x) => write! (f, "BogusClosure: {:?}", std::rc::Rc::as_ptr (x)),
 		}
 	}
 }
 
+impl From <BogusClosure> for Value {
+	fn from (x: BogusClosure) -> Self {
+		Self::BogusClosure (Rc::new (RefCell::new (x)))
+	}
+}
+
 impl From <bool> for Value {
 	fn from (x: bool) -> Self {
 		Self::Boolean (x)
@@ -156,6 +180,13 @@ impl PartialEq <i64> for Value {
 }
 
 impl Value {
+	pub fn as_closure (&self) -> Option <&Rc <RefCell <BogusClosure>>> {
+		match self {
+			Self::BogusClosure (x) => Some (x),
+			_ => None,
+		}
+	}
+	
 	/// Coerces ints to float
 	
 	pub fn as_float (&self) -> Option <f64> {
@@ -200,12 +231,20 @@ impl Value {
 	}
 }
 
-#[derive (Debug, Default, Eq, PartialEq)]
+#[derive (Default, Eq, PartialEq)]
 pub struct Table {
 	array: Vec <Value>,
 	hash: HashMap <Value, Value>,
 }
 
+impl fmt::Debug for Table {
+	fn fmt (&self, f: &mut fmt::Formatter) -> fmt::Result {
+		write! (f, "Table {:#?}", self.hash)?;
+		
+		Ok (())
+	}
+}
+
 impl Table {
 	fn get_inner (&self, key: &Value) -> Value {
 		self.hash.get (key).cloned ().unwrap_or_default ()

test_vectors/closure.lua

@@ -1,11 +1,11 @@
-local function make_closure (x)
-	print (x)
+local function make_closure (t)
 	return function (y)
-		return x + y
+		return t.x + y
 	end
 end
 
-local f = make_closure (11)
+local f = make_closure ({ x = 11 })
+local t = {}
 local x = f (12)
 print (x)
 return x

test_vectors/fma.lua

@@ -1,5 +1,7 @@
 -- This one fails :( I haven't implemented closures properly yet.
 
+local ii = "bogus"
+
 local function add (aa, bb)
 	return aa + bb
 end
@@ -12,6 +14,13 @@ local function fma (ee, ff, gg)
 	return add (mul (ee, ff), gg)
 end
 
-local hh = fma (10, 11, 12)
-print (hh)
+local function run ()
+	local hh = fma (10, 11, 12)
+	print (hh)
+	return hh
+end
+
+local hh = run ()
+print (ii)
+
 return hh