lysp: add dotted pair notation

userspace/lib/lysp/src/parse.rs

@@ -11,7 +11,7 @@ use nom::{
     combinator::{map, map_res, opt, recognize, value, verify},
     error::{Error, ErrorKind, FromExternalError, ParseError},
     multi::{fold, fold_many1, many0},
-    sequence::{delimited, preceded},
+    sequence::{delimited, pair, preceded},
 };
 
 use crate::vm::value::{Keyword, NumberValue, Value, Vector};
@@ -331,8 +331,25 @@ fn parse_vector(input: &str) -> IResult<&str, Value> {
     .parse(input)
 }
 
+fn parse_dotted_cons(input: &str) -> IResult<&str, Value> {
+    delimited(
+        char('('),
+        pair(
+            preceded(skip_comment_and_whitespace, parse_value),
+            preceded(
+                pair(skip_comment_and_whitespace, char('.')),
+                preceded(skip_comment_and_whitespace, parse_value),
+            ),
+        ),
+        preceded(skip_comment_and_whitespace, char(')')),
+    )
+    .map(|(a, b)| a.cons(b))
+    .parse(input)
+}
+
 pub fn parse_value(input: &str) -> IResult<&str, Value> {
     alt((
+        parse_dotted_cons,
         parse_list_or_nil,
         parse_vector,
         parse_boolean,
@@ -353,9 +370,9 @@ mod tests {
 
     use crate::{
         parse::{
-            OverflowError, parse_boolean, parse_identifier, parse_identifier_or_keyword_or_nil,
+            OverflowError, parse_boolean, parse_dotted_cons, parse_identifier,
-            parse_integer, parse_integer_dec, parse_integer_hex, parse_integer_oct,
+            parse_identifier_or_keyword_or_nil, parse_integer, parse_integer_dec,
-            parse_list_or_nil, parse_value,
+            parse_integer_hex, parse_integer_oct, parse_list_or_nil, parse_value,
         },
         vm::value::{Keyword, Value},
     };
@@ -514,6 +531,27 @@ mod tests {
         assert_eq!(v, Value::Boolean(false.into()));
     }
 
+    #[test]
+    fn test_dotted_pair() {
+        let (r, v) = parse_dotted_cons("(a.b)").unwrap();
+        assert_eq!(r, "");
+        assert_eq!(
+            v,
+            Value::Identifier("a".into()).cons(Value::Identifier("b".into()))
+        );
+        let (r, v) = parse_dotted_cons("(a .(b. ( c . (d.NIL ) )))").unwrap();
+        assert_eq!(r, "");
+        assert_eq!(
+            v,
+            Value::list_or_nil([
+                Value::Identifier("a".into()),
+                Value::Identifier("b".into()),
+                Value::Identifier("c".into()),
+                Value::Identifier("d".into()),
+            ])
+        );
+    }
+
     #[test]
     fn test_value() {
         let (r, v) = parse_value("+123\n").unwrap();

userspace/lib/lysp/src/vm/machine.rs

@@ -857,6 +857,7 @@ mod tests {
         let env = Rc::new(Environment::default());
         // (lambda (y) (let (x 123) (+ x y)))
         let lambda_function = Rc::new(BytecodeFunction {
+            script: None,
             identifier: None,
             docstring: None,
             instructions: [
@@ -906,6 +907,7 @@ mod tests {
         let env = Rc::new(Environment::default());
         // (lambda (x y) (+ x y))
         let lambda_function = Rc::new(BytecodeFunction {
+            script: None,
             identifier: None,
             docstring: None,
             instructions: [