Added boilerplate and tests for let-binds

1 files changed, 30 insertions, 0 deletions

diff --git a/src/sexp/step.rs b/src/sexp/step.rs
index 535b183..e031fca 100644
--- a/src/sexp/step.rs
+++ b/src/sexp/step.rs
@@ -237,6 +237,36 @@ impl SExp {
     ///     scons(2, Nil))).step(),
     ///     Ok(scons(Vector, scons(1, scons(2, Nil))))
     /// );
+    /// ```
+    ///
+    /// **Let-bindings**
+    /// ```rust
+    /// use myslip::sexp::{SExp::*, SLeaf::*, util::*};
+    ///
+    /// assert_eq!(
+    ///     scons(
+    ///         scons(Let, scons(var("x"), scons(5, Nil))), scons(
+    ///             scons(Add, scons(var("x"), scons(1, Nil))), Nil
+    ///         )
+    ///     ).step(),
+    ///     Ok(scons(Add, scons(5, scons(1, Nil))))
+    /// );
+    /// assert_eq!(
+    ///     scons(
+    ///         scons(Let, scons(var("y"), scons(4, Nil))),
+    ///         scons(
+    ///             scons(Let, scons(var("x"), scons(5, Nil))),
+    ///             scons(scons(Add, scons(var("x"), scons(var("y"), Nil))), Nil)
+    ///         )
+    ///     ).step(),
+    ///     Ok(scons(
+    ///         scons(Let, scons(var("x"), scons(5, Nil))), scons(
+    ///             scons(Add, scons(var("x"), scons(1, Nil))), Nil
+    ///         )
+    ///     ))
+    /// );
+    /// ```
+    /// 
     pub fn step(self) -> Result<Self, String> {
         match self {