Is there an “opposite” to the null coalescing operator? (…in any language?)

Question

null coalescing translates roughly to return x, unless it is null, in which case return y

I often need return null if x is null, otherwise return x

Answer 1

It just felt right to add this as an answer.

I guess the reason why there is no such thing in C# is because, unlike the coalescing operator (which is only valid for reference types), the reverse operation could yield either a reference or value type (i.e. class x with member int y - therefore it would unfortunately be unusable in many situations.

I'm not saying, however, that I wouldn't like to see it!

A potential solution to that problem would for the operator to automatically lift a value type expression on the right-hand-side to a nullable. But then you have the issue that x.y where y is an int will actually return an int? which would be a pain.

Another, probably better, solution would be for the operator to return the default value (i.e. null or zero) for the type on the right hand side if the expression on the left is null. But then you have issues distinguishing scenarios where a zero/null was actually read from x.y or whether it was supplied by the safe-access operator.