main: print parse stats when parse errors

src/main.rs

@@ -184,6 +184,13 @@ fn subst() -> Result<(), Box<dyn Error>> {
     }
 }
 
+fn plural(count: usize) -> &'static str {
+    match count {
+        1 => "",
+        _ => "s",
+    }
+}
+
 fn parse(document: &str) {
     let mut parser = Parser::new(Lexer::new(document));
     let verbose = !matches!(
@@ -193,11 +200,21 @@ fn parse(document: &str) {
     for idx in 0.. {
         match parser.parse::<Expr>(0) {
             Err(e @ ParseError::EOF(s)) if s.tail == document.len() as _ => {
-                println!("\x1b[92m{e} (total {} bytes)\x1b[0m", document.len());
+                println!(
+                    "\x1b[92m{e} (total {} byte{}, {idx} expression{})\x1b[0m",
+                    document.len(),
+                    plural(document.len()),
+                    plural(idx),
+                );
                 break;
             }
             Err(e @ ParseError::EOF(_)) => {
-                println!("\x1b[93m{e} (total {} bytes)\x1b[0m", document.len());
+                println!(
+                    "\x1b[93m{e} (total {} byte{}, {idx} expression{})\x1b[0m",
+                    document.len(),
+                    plural(document.len()),
+                    plural(idx),
+                );
                 break;
             }
             Err(e) => {