diff --git a/doc/tutorial/basics/coalesce.md b/doc/tutorial/basics/coalesce.md
index 41fbfce..3a487a0 100644
--- a/doc/tutorial/basics/coalesce.md
+++ b/doc/tutorial/basics/coalesce.md
@@ -11,12 +11,20 @@
 In the example the fallback values are specified
 for `a` and `b` in case the list index is out of bounds.
 
+To do actual null coalescing one can unify a result with the desired type
+to force an error.
+In that case the default will be used if either the lookup fails or
+the result is not of the desired type.
+
 <!-- CUE editor -->
 ```
 list: [ "Cat", "Mouse", "Dog" ]
 
 a: list[0] | "None"
 b: list[5] | "None"
+
+n: [null]
+v: n[0] & string | "default"
 ```
 
 <!-- result -->
@@ -25,4 +33,6 @@
 
 a: "Cat"
 b: "None"
+n: [null]
+v: "default"
 ```
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