cue: allow comparison against null
this is partly in preparation for unary comparators, where
this is essential.
Change-Id: I73454a3b9ea446d61097404042f3260d6ec4593a
diff --git a/doc/ref/spec.md b/doc/ref/spec.md
index 8fba6dd..d68024a 100644
--- a/doc/ref/spec.md
+++ b/doc/ref/spec.md
@@ -1598,6 +1598,8 @@
The ordering operators `<`, `<=`, `>`, and `>=` apply to operands that are ordered.
These terms and the result of the comparisons are defined as follows:
+- Null is comparable with itself and any other type.
+ Two null values are always equal, null is unequal with anything else.
- Boolean values are comparable.
Two boolean values are equal if they are either both true or both false.
- Integer values are comparable and ordered, in the usual way.
@@ -1606,16 +1608,12 @@
- String values are comparable and ordered, lexically byte-wise after
normalization to Unicode normal form NFC.
- Struct are not comparable.
- Two struct values are equal if their corresponding non-blank fields are equal.
-- Lists are comparable.
- Two list values are equal if their corresponding elements are equal.
+- Lists are not comparable.
```
-c: 3 < 4
-
-x: int
-y: int
-
-b3: x == y // b3 has type bool
+a: 3 < 4 // true
+b: null == 2 // false
+c: null != {} // true
+d: {} == {} // _|_: structs are not comparable against structs
```
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