Introduce symbols

1 files changed, 9 insertions, 1 deletions

diff --git a/rust/src/lambda.rs b/rust/src/lambda.rs
index 7601640..ccb8c28 100644
--- a/rust/src/lambda.rs
+++ b/rust/src/lambda.rs
@@ -14,6 +14,7 @@ pub fn run(arg: &str) -> String {
 pub enum Value {
     Num(i32),
     Bool(bool),
+    Sym(String),
 }
 
 impl Display for Value {
@@ -21,6 +22,7 @@ impl Display for Value {
         match self {
             Value::Num(i) => write!(f, "{}", i),
             Value::Bool(b) => write!(f, "{}", b),
+            Value::Sym(s) => write!(f, "{}", s),
         }
     }
 }
@@ -29,7 +31,7 @@ fn interpret(arg: &str) -> Value {
     arg.parse::<i32>()
         .map(Value::Num)
         .or(arg.parse::<bool>().map(Value::Bool))
-        .unwrap()
+        .unwrap_or(Value::Sym(arg.to_string()))
 }
 
 #[cfg(test)]
@@ -46,9 +48,15 @@ mod tests {
             }
 
     }
+
     #[test]
     fn interpret_truth_values_as_booleans() {
         assert_eq!(Bool(true), interpret("true"));
         assert_eq!(Bool(false), interpret("false"));
     }
+
+    #[test]
+    fn interpret_identifiers_values_as_symbols() {
+        assert_eq!(Sym("foo".to_string()), interpret("foo"));
+    }
 }