validation: allow numbers to be keyed locations

While it's not a good idea to use a floating point as a key, they do
come up and are allowed by other important systems (such as PostgreSQL).

We should support them too.

crates/json/src/schema/types.rs

@@ -274,9 +274,9 @@ impl Set {
     ///
     /// assert!(STRING.is_keyable_type());
     /// assert!(INTEGER.is_keyable_type());
-    /// assert!(!FRACTIONAL.is_keyable_type());
+    /// assert!(FRACTIONAL.is_keyable_type());
     /// assert!(BOOLEAN.is_keyable_type());
-    /// assert!(!INT_OR_FRAC.is_keyable_type());
+    /// assert!(INT_OR_FRAC.is_keyable_type());
     /// assert!((STRING | NULL).is_keyable_type());
     ///
     /// assert!(!(NULL.is_keyable_type()));
@@ -289,7 +289,7 @@ impl Set {
     /// ```
     pub fn is_keyable_type(&self) -> bool {
         match *self - NULL {
-            BOOLEAN | INTEGER | STRING => true,
+            BOOLEAN | INTEGER | INT_OR_FRAC | FRACTIONAL | STRING => true,
             _ => false,
         }
     }

crates/validation/src/errors.rs

@@ -81,7 +81,7 @@ pub enum Error {
     PtrRegexUnmatched { ptr: String, unmatched: String },
     #[error("location {ptr} is prohibited from ever existing by the schema {schema}")]
     PtrCannotExist { ptr: String, schema: Url },
-    #[error("location {ptr} accepts {type_:?} in schema {schema}, but locations used as keys may only be null-able integers, strings, or booleans")]
+    #[error("location {ptr} accepts {type_:?} in schema {schema}, but locations used as keys may only be null-able numbers, strings, or booleans")]
     KeyWrongType {
         ptr: String,
         type_: types::Set,

crates/validation/tests/snapshots/scenario_tests__keyed_location_wrong_type.snap

@@ -5,34 +5,34 @@ expression: errors
 [
     Error {
         scope: test://example/int-halve#/collections/testing~1int-halve/key/0,
-        error: location /int accepts "number", "object" in schema test://example/canonical/int-string-len.schema, but locations used as keys may only be null-able integers, strings, or booleans,
+        error: location /int accepts "number", "object" in schema test://example/canonical/int-string-len.schema, but locations used as keys may only be null-able numbers, strings, or booleans,
     },
     Error {
         scope: test://example/int-reverse#/collections/testing~1int-reverse/key/0,
-        error: location /int accepts "number", "object" in schema test://example/int-string.schema, but locations used as keys may only be null-able integers, strings, or booleans,
+        error: location /int accepts "number", "object" in schema test://example/int-string.schema, but locations used as keys may only be null-able numbers, strings, or booleans,
     },
     Error {
         scope: test://example/int-string#/collections/testing~1int-string/key/0,
-        error: location /int accepts "number", "object" in schema test://example/int-string.schema, but locations used as keys may only be null-able integers, strings, or booleans,
+        error: location /int accepts "number", "object" in schema test://example/int-string.schema, but locations used as keys may only be null-able numbers, strings, or booleans,
     },
     Error {
         scope: test://example/int-string#/collections/testing~1int-string-ref-write-schema/key/0,
-        error: location /int accepts "number", "object" in schema test://example/int-string.schema, but locations used as keys may only be null-able integers, strings, or booleans,
+        error: location /int accepts "number", "object" in schema test://example/int-string.schema, but locations used as keys may only be null-able numbers, strings, or booleans,
     },
     Error {
         scope: test://example/int-string#/collections/testing~1int-string-ref-write-schema/key/0,
-        error: location /int accepts "number", "object" in schema test://example/int-string#/collections/testing~1int-string-ref-write-schema/readSchema, but locations used as keys may only be null-able integers, strings, or booleans,
+        error: location /int accepts "number", "object" in schema test://example/int-string#/collections/testing~1int-string-ref-write-schema/readSchema, but locations used as keys may only be null-able numbers, strings, or booleans,
     },
     Error {
         scope: test://example/int-string#/collections/testing~1int-string-rw/key/0,
-        error: location /int accepts "number", "object" in schema test://example/int-string.schema, but locations used as keys may only be null-able integers, strings, or booleans,
+        error: location /int accepts "number", "object" in schema test://example/int-string.schema, but locations used as keys may only be null-able numbers, strings, or booleans,
     },
     Error {
         scope: test://example/int-string#/collections/testing~1int-string-rw/key/0,
-        error: location /int accepts "number", "object" in schema test://example/canonical/int-string-len.schema, but locations used as keys may only be null-able integers, strings, or booleans,
+        error: location /int accepts "number", "object" in schema test://example/canonical/int-string-len.schema, but locations used as keys may only be null-able numbers, strings, or booleans,
     },
     Error {
         scope: test://example/int-string#/collections/testing~1int-string.v2/key/0,
-        error: location /int accepts "number", "object" in schema test://inlined/canonical/id, but locations used as keys may only be null-able integers, strings, or booleans,
+        error: location /int accepts "number", "object" in schema test://inlined/canonical/id, but locations used as keys may only be null-able numbers, strings, or booleans,
     },
 ]