1 files changed, 27 insertions, 0 deletions
diff --git a/src/sexp/mod.rs b/src/sexp/mod.rs
new file mode 100644
index 0000000..c920e41
--- /dev/null
+++ b/src/sexp/mod.rs
@@ -0,0 +1,27 @@
+
+pub mod step;
+pub mod util;
+
+/// A leaf node for S-Expressions.
+///
+/// May represent built-in operators,
+/// variables (to be added), functions
+/// (to be added) or values.
+#[derive(Debug)]
+#[derive(PartialEq)]
+pub enum SLeaf {
+    Add,
+    Sub,
+    Mul,
+    Div,
+    Int(i32),
+}
+
+/// An S-Expression; the defining structure of the language.
+#[derive(Debug)]
+#[derive(PartialEq)]
+pub enum SExp {
+    SCons(Box<SExp>, Box<SExp>),
+    Atom(SLeaf),
+}
+