Re: Range to Nullable conversion

[Paul Backus via Digitalmars-d-learn]

On Friday, 10 June 2022 at 17:22:53 UTC, Antonio wrote:

Can this code be written as a **simple** expression? (without having to write helper methods).

```d
import std.range, std.typecons;

Nullable!(ElementType!R) maybeFront(R)(auto ref R r)
    if (isInputRange!R)
{
    if (r.empty)
        return typeof(return)();
    else
        return nullable(r.front);
}

unittest
{
    int[] a = [1, 2, 3];
    int[] b;

    assert(a.maybeFront == nullable(1));
    assert(b.maybeFront.isNull);
}
```