Added tons of opcode documentation, changed license to ISC and a lot of file refactoring.

src/vm/to_string.c

@@ -1,3 +1,42 @@
+/**
+ * This file is part of the Fun programming language.
+ * https://hanez.org/project/fun/
+ *
+ * Copyright 2025 Johannes Findeisen <you@hanez.org>
+ * Licensed under the terms of the ISC license.
+ * https://opensource.org/license/isc-license-txt
+ */
+
+/**
+* @file to_string.c
+ * @brief Implements the OP_TO_STRING opcode for converting values to strings in the VM.
+ *
+ * This file handles the OP_TO_STRING instruction, which converts a value of any type
+ * into its string representation and pushes the result onto the stack.
+ *
+ * Behavior:
+ * - Pops a value from the stack.
+ * - Converts the value to a string based on its type:
+ *   - Integers: Convert to decimal string (e.g., 42 → "42")
+ *   - Strings: Return a copy of the string
+ *   - Arrays: Convert to "[array n=<length>]"
+ *   - Maps: Convert to "{map n=<length>}"
+ *   - Functions: Convert to "<function@<address>>"
+ *   - Nil: Convert to "nil"
+ * - Pushes the resulting string onto the stack.
+ *
+ * Error Handling:
+ * - Exits with an error if memory allocation fails during string creation.
+ *
+ * Example:
+ * // Bytecode: OP_TO_STRING
+ * // Stack before: [42]
+ * // Stack after: ["42"]
+ *
+ * @author Johannes Findeisen
+ * @date 2025-10-16
+ */
+
 case OP_TO_STRING: {
     Value v = pop_value(vm);
     char *s = value_to_string_alloc(&v);