From 313c044b4a878a425aaca6554576f5154ace8ff9 Mon Sep 17 00:00:00 2001
From: Joel Kronqvist <joel.kronqvist@iki.fi>
Date: Wed, 6 Aug 2025 16:23:18 +0300
Subject: Implemented let-bindings

---
 src/sexp/subst.rs | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

(limited to 'src/sexp/subst.rs')

diff --git a/src/sexp/subst.rs b/src/sexp/subst.rs
index 87f9b50..4cfa48d 100644
--- a/src/sexp/subst.rs
+++ b/src/sexp/subst.rs
@@ -17,7 +17,14 @@ impl SExp {
     /// ```
     pub fn subst(self, name: &str, value: &SExp) -> SExp {
         match self {
-            SCons(a, b) => scons((*a).subst(name, value), (*b).subst(name, value)),
+            SCons(a, b) => {
+                if let Some((varname, _)) = a.clone().check_let() {
+                    if &varname == name {
+                        return SCons(a, b);
+                    }
+                }
+                scons((*a).subst(name, value), (*b).subst(name, value))
+            },
             Atom(Var(x)) if x == name => value.clone(),
             t => t,
         }
-- 
cgit v1.2.3