diff --git a/sexpr.ml b/sexpr.ml
index 4bcd027..e01c7cb 100644
--- a/sexpr.ml
+++ b/sexpr.ml
@@ -718,12 +718,37 @@ module SExprMacroExp = struct
         in
         Nil, false, ctx
       end
-    | Cons(Id ":c-eq", Cons(l, Cons(r, Nil))) -> begin
-        if l = r then
-          Nil, true, ctx
-        else
-          Cons(Nil, Nil), true, ctx
-      end
+    | Cons(Id ":atm-to-str", Cons(Id x, Nil))
+    | Cons(Id ":atm-to-str", Cons(Str x, Nil)) ->
+        li1 (Str x), true, ctx
+    | Cons(Id ":atm-to-str", Cons(Int x, Nil)) ->
+        li1 (Str (Int.to_string x)), true, ctx
+    | Cons(Id ":atm-to-str", Cons(Flt x, Nil)) ->
+        li1 (Str (Float.to_string x)), true, ctx
+    | Cons(Id ":str-cat", Cons(Str l, Cons(Str r, Nil))) ->
+        li1 (Str (l ^ r)), true, ctx
+    | Cons(Id ":c-eq", Cons(l, Cons(r, Nil))) when l = r ->
+        Nil, true, ctx
+    | Cons(Id ":c-int", Cons(Int _, Nil)) ->
+        Nil, true, ctx
+    | Cons(Id ":c-float", Cons(Flt _, Nil)) ->
+        Nil, true, ctx
+    | Cons(Id ":c-num", Cons(Int _, Nil))
+    | Cons(Id ":c-num", Cons(Flt _, Nil)) ->
+        Nil, true, ctx
+    | Cons(Id ":c-str", Cons(Str _, Nil)) ->
+        Nil, true, ctx
+    | Cons(Id ":c-id", Cons(Id _, Nil)) ->
+        Nil, true, ctx
+    | Cons(Id ":c-list", Cons(x, Nil)) when is_list x ->
+        Nil, true, ctx
+    | Cons(Id ":c-atm", Cons(Int _, Nil))
+    | Cons(Id ":c-atm", Cons(Flt _, Nil))
+    | Cons(Id ":c-atm", Cons(Str _, Nil))
+    | Cons(Id ":c-atm", Cons(Id _, Nil)) ->
+        Nil, true, ctx
+    | Cons(Id ":c-atm", Cons(x, Nil)) when is_list x ->
+        Nil, true, ctx
     | Cons(Id i, r) when String.starts_with ~prefix:":" i ->
         let i = String.sub i 1 ((String.length i) - 1) in
         check_expands_macro i ctx r s