fix: correct --version behavior (fixes #10)

src/args.rs

@@ -3,9 +3,10 @@ use clap::Parser;
 use std::path::PathBuf;
 
 #[derive(Debug, Clone, Parser)]
+#[command(arg_required_else_help(true))]
 pub struct Args {
-    #[clap(long = "lua", help = "Path to lua program to be executed")]
-    pub lua: PathBuf,
+    #[clap(help = "Path to lua program to be executed")]
+    pub lua: Option<PathBuf>,
     #[clap(long = "version", short = 'V', help = "Print version info and exit")]
     pub version: bool,
 }

src/main.rs

@@ -30,9 +30,13 @@ fn main() -> Result<()> {
         return Ok(());
     }
 
-    let program = load_file(&args.lua.to_string_lossy())?;
-
-    Ok(lua::execute(&program)?)
+    if let Some(lua) = &args.lua {
+        let program = load_file(&lua.to_string_lossy())?;
+        Ok(lua::execute(&program)?)
+    } else {
+        // Help will be printed out by Args.
+        Ok(())
+    }
 }
 
 /// Loads a file content as `String`.