comments on spec and a few other things
Change-Id: I154e452946209a158a8b6fbfb7579801a8186879
diff --git a/doc/tutorial/basics/coalesce.md b/doc/tutorial/basics/coalesce.md
index 3a487a0..082708a 100644
--- a/doc/tutorial/basics/coalesce.md
+++ b/doc/tutorial/basics/coalesce.md
@@ -4,6 +4,15 @@
# Null Coalescing
+<!-- jba: the terms here are confusing. "Null coalescing" is actually not
+ that, but then there is something called "actual null coalescing."
+
+ Just say that because _|_ | X evaluates to X, you can use disjunction
+ to represent fallback values.
+
+ And then you can use that to effectively type-check with a default value.
+-->
+
With null coalescing we really mean error, or bottom, coalescing.
The defaults mechanism for disjunctions can also be
used to provide fallback values in case an expression evaluates to bottom.
@@ -35,4 +44,4 @@
b: "None"
n: [null]
v: "default"
-```
\ No newline at end of file
+```
