Proposal: Allow block-statements with return values everywhere an expression is expected

[YaakovDavis]

I propose to allow the following syntax:

var x = {var foo = Foo(); return foo * 3;};

As another example, in ternary operators, this will look like:
var x = condition ? {var foo = Bar(); return foo + 1;} : 2;

Such a syntax increases the composability of the language, allowing one to express logic using a natural flow, while also limiting the scope of local intermediary variables.
F# has a similar syntax, allowing to define arbitrarily nested expressions.

[orthoxerox]

#6182

[qrli]

also related to #15651

[binki]

I think seeing return inside of a straight up block would be confusing with existing syntax. This code is valid syntax currently and causes a return from MyMethod:

static int MyMethod()
{
    var x = 2;
    {
        return x + 4;
    }
    // unreachable.
}

With this proposed syntax, you could do:

static in MyMethod()
{
    var x = 2;
    var y = {
        return x + 4;
    };
    // Suddenly this is reachable.
    return y;
}

In quickly visually scanning a method, it seems like the return in a “returnable block” is not visually distinguishable from a return in a nested block which causes the outer function to return. This issue is described here too.

[YaakovDavis]

@binki

To me, the 2 snippets look visually distinct.
In any case, it has been proposed elsewhere to use the following syntax:

var y = ({
   return 4;
});

[CyrusNajmabadi]

Closing this out. We're doing all language design now at dotnet/csharplang. If you're still interested in this idea let us know and we can migrate this over to a discussion in that repo. Thanks!