Add string concatenation

dust-lang/src/native_function/assert.rs

@@ -9,7 +9,7 @@ pub fn panic(data: &mut Thread, _: usize, argument_range: Range<usize>) {
     for register_index in argument_range {
         let string = data.get_string_register(register_index);
 
-        message.push_str(&string);
+        message.push_str(string);
         message.push('\n');
     }
 

dust-lang/src/native_function/random.rs

@@ -2,7 +2,7 @@ use std::ops::Range;
 
 use rand::Rng;
 
-use crate::{Value, vm::Thread};
+use crate::vm::Thread;
 
 pub fn random_int(data: &mut Thread, destination: usize, argument_range: Range<usize>) {
     let mut argument_range_iter = argument_range.into_iter();

dust-lang/src/vm/action.rs

@@ -120,11 +120,43 @@ pub fn add(instruction: InstructionBuilder, thread: &mut Thread) {
             };
             let result = left_value + right_value;
 
-            println!("{left} + {right} = {destination}");
-            println!("{left_value} + {right_value} = {result}");
-
             thread.set_integer_register(destination, result);
         }
+        (TypeCode::STRING, TypeCode::STRING) => {
+            let left_value = if left_is_constant {
+                if cfg!(debug_assertions) {
+                    thread.get_constant(left).as_string().unwrap().clone()
+                } else {
+                    unsafe {
+                        thread
+                            .get_constant(left)
+                            .as_string()
+                            .unwrap_unchecked()
+                            .clone()
+                    }
+                }
+            } else {
+                thread.get_string_register(left).clone()
+            };
+            let right_value = if right_is_constant {
+                if cfg!(debug_assertions) {
+                    thread.get_constant(right).as_string().unwrap().clone()
+                } else {
+                    unsafe {
+                        thread
+                            .get_constant(right)
+                            .as_string()
+                            .unwrap_unchecked()
+                            .clone()
+                    }
+                }
+            } else {
+                thread.get_string_register(right).clone()
+            };
+            let result = left_value + &right_value;
+
+            thread.set_string_register(destination, result);
+        }
         _ => unimplemented!(),
     }
 }

dust-lang/src/vm/thread.rs

@@ -10,7 +10,7 @@ pub struct Thread {
     chunk: Arc<Chunk>,
     call_stack: Vec<CallFrame>,
     pub return_value: Option<Option<Value>>,
-    spawned_threads: Vec<JoinHandle<()>>,
+    _spawned_threads: Vec<JoinHandle<()>>,
 }
 
 impl Thread {
@@ -24,7 +24,7 @@ impl Thread {
             chunk,
             call_stack,
             return_value: None,
-            spawned_threads: Vec::new(),
+            _spawned_threads: Vec::new(),
         }
     }