From 1e66554b8e4f05da5c61fa8760ed34f3905505c3 Mon Sep 17 00:00:00 2001
From: Sam Caldwell <samcaldwell@utexas.edu>
Date: Thu, 17 May 2018 12:17:27 -0400
Subject: [PATCH] note on performance

---
 racket/typed/core.rkt | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/racket/typed/core.rkt b/racket/typed/core.rkt
index 708c431..6299c5c 100644
--- a/racket/typed/core.rkt
+++ b/racket/typed/core.rkt
@@ -126,7 +126,9 @@
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; User Defined Types, aka Constructors
 
-;; τ.norm in 1st case causes "not valid type" error when file is compiled
+;; τ.norm in 1st case causes "not valid type" error when referring to ⊥ in another file.
+;; however, this version expands the type at every reference, incurring a potentially large
+;; overhead---2x in the case of book-club.rkt
 ;; (copied from ext-stlc example)
 (define-syntax define-type-alias
   (syntax-parser