2448

1 files changed, 2 insertions, 0 deletions

diff --git a/021check_instruction.cc b/021check_instruction.cc
index 15d14afc..57757446 100644
--- a/021check_instruction.cc
+++ b/021check_instruction.cc
@@ -73,6 +73,8 @@ recipe main [
 +error: main: can't copy 34 to 1:address:number; types don't match
 
 :(code)
+// copy arguments because later layers will want to make changes to them
+// without perturbing the caller
 bool types_match(reagent lhs, reagent rhs) {
   // '_' never raises type error
   if (is_dummy(lhs)) return true;