3 files changed, 100 insertions, 0 deletions
diff --git a/lisp/src/ast.rs b/lisp/src/ast.rs
new file mode 100644
index 0000000..8cac963
--- /dev/null
+++ b/lisp/src/ast.rs
@@ -0,0 +1,7 @@
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum Val {
+    Atom(String),
+    List(Vec<Self>),
+    I64(i64),
+    String(String),
+}
diff --git a/lisp/src/lib.rs b/lisp/src/lib.rs
new file mode 100644
index 0000000..60d0a4e
--- /dev/null
+++ b/lisp/src/lib.rs
@@ -0,0 +1,16 @@
+pub mod parser;
+pub mod ast;
+
+pub fn my_fn() -> bool {
+    true
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn it_works() {
+        assert!(my_fn());
+    }
+}
diff --git a/lisp/src/parser.rs b/lisp/src/parser.rs
new file mode 100644
index 0000000..e36bdf7
--- /dev/null
+++ b/lisp/src/parser.rs
@@ -0,0 +1,77 @@
+use chumsky::prelude::*;
+
+use crate::ast::Val;
+
+pub fn parser<'a>() -> impl Parser<char, Vec<Val>, Error = Simple<char>> {
+    recursive(|val| {
+        let string = just('"')
+            .ignore_then(none_of('"').repeated())
+            .then_ignore(just('"'))
+            .collect::<String>()
+            .map(Val::String)
+            .padded();
+
+        let atom = filter(|c: &char| c.is_alphanumeric())
+            .map(Some)
+            .chain::<char, _, _>(filter(|c: &char| c.is_alphanumeric()).repeated())
+            .collect::<String>()
+            .map(Val::Atom)
+            .padded();
+
+        let number = just('-')
+            .or_not()
+            .chain::<char, _, _>(text::int(10))
+            .collect::<String>()
+            .from_str()
+            .unwrapped()
+            .map(Val::I64)
+            .labelled("number");
+
+        choice((
+            string, //
+            number,
+            atom,
+            val.delimited_by(just('('), just(')')).map(Val::List),
+        ))
+        .repeated()
+    })
+    .then_ignore(end())
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn parse_atom() {
+        assert_eq!(
+            Ok(vec!(Val::Atom("foo".to_string()))),
+            parser().parse("foo")
+        );
+    }
+
+    #[test]
+    fn parse_string() {
+        assert_eq!(
+            Ok(vec!(Val::String("foo".to_string()))),
+            parser().parse("\"foo\"")
+        );
+    }
+
+    #[test]
+    fn parse_i64() {
+        assert_eq!(Ok(vec!(Val::I64(123))), parser().parse("123"));
+        assert_eq!(Ok(vec!(Val::I64(-643))), parser().parse("-643"));
+    }
+
+    #[test]
+    fn parse_list() {
+        assert_eq!(
+            Ok(vec!(Val::List(vec!(
+                Val::Atom("a".to_string()),
+                Val::Atom("b".to_string())
+            )))),
+            parser().parse("(a b)")
+        );
+    }
+}