From 046b9b0c87e260985aa2ac9f21dd6203a95c88a1 Mon Sep 17 00:00:00 2001
From: Alexander Rosenberg <zanderpkg@pm.me>
Date: Sun, 19 Jul 2026 02:45:15 -0700
Subject: [PATCH] Fix lexical and dynamic binding

---
 lisp/kernel.gl |  3 ++-
 src/lisp.c     | 25 ++++++++++++++++---------
 src/stack.c    |  4 ++--
 3 files changed, 20 insertions(+), 12 deletions(-)

diff --git a/lisp/kernel.gl b/lisp/kernel.gl
index f2ef857..0807424 100644
--- a/lisp/kernel.gl
+++ b/lisp/kernel.gl
@@ -4,7 +4,8 @@
 
 (print print-circular)
 
-(let ((print-circular nil))
+(let ((print-circular nil)
+      (b t))
   (test))
 
 (print print-circular)
diff --git a/src/lisp.c b/src/lisp.c
index 0e55848..64e1bc3 100644
--- a/src/lisp.c
+++ b/src/lisp.c
@@ -135,20 +135,27 @@ DEFSPECIAL(let, "let", (LispVal * bindings, LispVal *body),
            "(bindings &rest body)", "") {
     CHECK_LISTP(bindings);
     StackFrame *stack_ref = LISP_STACK_REF();
-    LispVal *lexenv = Vlexical_environment;
     DOLIST(binding, bindings) {
-        if (SYMBOLP(binding)) {
-            lexenv = CONS(binding, CONS(Qnil, lexenv));
-        } else if (CONSP(binding) && list_length_eq(binding, 2)) {
-            lexenv = CONS(
-                FIRST(binding),
-                CONS(Feval(SECOND(binding), Vlexical_environment), lexenv));
-        } else {
+        if (CONSP(binding) && list_length_eq(binding, 2)) {
+            if (!SYMBOLP(XCAR(binding))) {
+                // TODO better error
+                abort();
+            }
+            RPLACA(XCDR(binding), Feval(SECOND(binding), Vlexical_environment));
+        } else if (!SYMBOLP(binding)) {
             // TODO better error
             abort();
         }
     }
-    push_dynamic_binding(Qlexical_environment, lexenv);
+    push_copy_lexenv();
+    DOLIST(binding, bindings) {
+        // we already checked that all bindings are well formed
+        if (SYMBOLP(binding)) {
+            new_lexical_variable(binding, Qnil);
+        } else {
+            new_lexical_variable(FIRST(binding), SECOND(binding));
+        }
+    }
     return UNWIND_AND_RETURN(stack_ref, Fprogn(body));
 }
 
diff --git a/src/stack.c b/src/stack.c
index e5b3335..f592668 100644
--- a/src/stack.c
+++ b/src/stack.c
@@ -252,7 +252,7 @@ void set_lexical_variable(LispVal *name, LispVal *value) {
         abort();
     }
     if (DYNAMIC_SYMBOL_P(name)) {
-        SET_SYMBOL_VALUE(name, value);
+        push_dynamic_binding(name, value);
     } else {
         Vlexical_environment = Fplist_put(Vlexical_environment, name, value);
     }
@@ -265,7 +265,7 @@ void new_lexical_variable(LispVal *name, LispVal *value) {
         abort();
     }
     if (DYNAMIC_SYMBOL_P(name)) {
-        SET_SYMBOL_VALUE(name, value);
+        push_dynamic_binding(name, value);
     } else {
         Vlexical_environment = CONS(name, CONS(value, Vlexical_environment));
     }