I'm trying to implement a custom operator for Collections similar to the Elvis operator (?: in kotlin, ?? in swift), but in addition to checking nullability, the operator also checks if the collection is Empty.

However, when I try to use the operator, the code doesn't compile. The compiler throws an "ambiguous use of operator" error.

The implementation of the ?? operator in the swift language seems to be really similar to mine, so I'm a little lost.. Any help to understand why this happens, and how to fix it, will be greatly appreciated.

---

```
/// Returns the first argument if it's not null and not empty, otherwise will return the second argument.
infix operator ?/ : NilCoalescingPrecedence

@inlinable func ?/ <T: Collection>(optional: T?, defaultValue: @autoclosure () throws -> T) rethrows -> T {
    if let value = optional,
       !value.isEmpty {
        return value
    } else {
        return try defaultValue()
    }
}

```

---

```
@inlinable func ?/ <T: Collection>(optional: T?, defaultValue: @autoclosure () throws -> T?) rethrows -> T? {
    if let value = optional,
       !value.isEmpty {
        return value
    } else {
        return try defaultValue()
    }
}

```

---

```
func test() {
    let optionalValue: String? = nil

    let value1: String = optionalValue ?? "default value" // This works
    let value2: String = optionalValue ?/ "default value" // This works
    let value3: String? = optionalValue ?/ nil // This works
    let value4: String? = optionalValue ?? nil // This works
    let value5: String? = optionalValue ?? "default value" // This works
    let value6: String? = optionalValue ?/ "default value" // This dont compile: Ambiguous use of operator '?/'
}

```

---

The standard implementation for the ?? operator can be found at: <https://github.com/apple/swift/blob/main/stdlib/public/core/Optional.swift>, just search for "?? <" in the browser.

Maybe I'm using the wrong approach to solve this problem. If anyone knows a better solution will be great too.