simple spans work, somewhat improved

src/ast/main.rs

@@ -10,5 +10,5 @@ fn main() {}
 
 #[test]
 fn loc() {
-    println!("{:?}", NumSeqParser::new().parse("1, 2").unwrap());
+    println!("{:?}", NumSeqParser::new().parse("1, 2, 54").unwrap());
 }

src/ast/parser.lalrpop

@@ -36,11 +36,11 @@ CommaNoTrail<T>: Vec<T> = {
 }
 
 pub NumSeq: Vec<(usize, usize, i32)> = {
-    CommaNoTrail<Num> 
+    CommaNoTrail<Spanned<Num>>, 
 } 
 
-pub Num: (usize, usize, i32) = {
-    <l: @L> <n: r"[0-9]+"> <r: @R> => (l, r, i32::from_str(n).unwrap()),
+pub Num: i32 = {
+    <n: r"[0-9]+"> => i32::from_str(n).unwrap(),
 };
 
 Id: String = {