Work

src/primitives.rs

@@ -27,13 +27,13 @@ pub fn one_of<'a>(items: &'static str) -> impl Parser<&'a str, char, ()> {
 }
 
 /// Parses a standard identifier in a programming language
-pub fn identifier(input: &str) -> ParseResult<&str, String, &str> {
+pub fn identifier(input: &str) -> ParseResult<&str, String, ()> {
     let mut chars = input.chars();
     let mut buf = String::new();
 
     match chars.next() {
         Some(ch) if ch.is_alphabetic() => buf.push(ch),
-        _ => return Err((input, input)),
+        _ => return Err(((), input)),
     }
 
     for next in chars {

src/test/sexp.rs

@@ -22,13 +22,16 @@ fn parse_sexp() {
         literal("#f").to(Atom::Bool(false)),
     ));
 
-    let parse_symbol = identifier;
+    let parse_symbol = identifier.map(Atom::Symbol);
     let parse_number = repeated(one_of("1234567890"))
         .at_least(1)
         .map(|n| Atom::Num(n.iter().collect::<String>().parse::<i64>().unwrap()));
 
-    let parser = choice((parse_bool, parse_number));
+    let parser = choice((parse_symbol, parse_bool, parse_number));
 
     let output = parser.parse("#t").unwrap();
     assert_eq!(output.0, Atom::Bool(true));
+
+    let output = parser.parse("384").unwrap();
+    assert_eq!(output.0, Atom::Num(384));
 }