davidchambers commented on issue #5582:
URL: https://github.com/apache/couchdb/issues/5582#issuecomment-3089184681
Thanks for your response, @rnewson. :)
It's a shame that special cases such as this will continue to be necessary:
```kotlin
// It should be acceptable to use {"creationEpoch": {"$and": []}} when
neither createdAfterInclusive
// nor createdBeforeExclusive is specified, but CouchDB does not understand
vacuous truth. 🙈
val creationSelector = listOfNotNull(
f.createdAfterInclusive?.let { mapOf("\$gte" to
it.toNanoEpoch().epoch.toString()) },
f.createdBeforeExclusive?.let { mapOf("\$lt" to
it.toNanoEpoch().epoch.toString()) },
).toNonEmptyListOrNull()?.let { mapOf("creationEpoch" to mapOf("\$and" to
it)) } ?: emptyMap()
```
I'd like to be able to write this instead:
```kotlin
val creationSelector = mapOf(
"creationEpoch" to mapOf(
"\$and" to listOfNotNull(
f.createdAfterInclusive?.let { mapOf("\$gte" to
it.toNanoEpoch().epoch.toString()) },
f.createdBeforeExclusive?.let { mapOf("\$lt" to
it.toNanoEpoch().epoch.toString()) },
),
),
)
```
> we are happy that `"$and": []` does not vacuously match everything
Could you elaborate? Are you concerned about backwards compatibility, or is
there some reason that CouchDB should behave differently from other programming
contexts?
Haskell:
```haskell
ghci> all even []
True
```
Python:
```python
>>> all(x % 2 == 0 for x in [])
True
```
JavaScript:
```javascript
> [].every(x => x % 2 === 0)
true
```
Clojure:
```clojure
user=> (every? even? [])
true
user=> (and)
true
```
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