return error() in match

[ghost]

V version: 0.3.2 993e21e
OS: ArchLinux

What did you do?

fn foo() !{
	s := match true {
		true { 'a' }
		else { return error('') }
	}
	println(s)
}

What did you expect to see?
No error, don't know if this is a bug or not.

What did you see instead?

bug.v:4:10: error: `match` expression requires an expression as the last statement of every branch
    2 |     s := match true {
    3 |         true { 'a' }
    4 |         else { return error('') }
      |                ~~~~~~~~~~~~~~~~
    5 |     }
    6 |     println(s)

[JalonSolov]

It is a logical error. Because you're trying to assign to a variable, it expects something assignable to come from every branch in the match.

A return statement doesn't give anything assignable, so you get the error message you saw.

You would need to change the code to something like

fn foo() !{
	s := match true {
		true { 'a' }
		else { '' }
	}

	if s == '' { return error('') }
	println(s)
}

[ghost]

I know it. This is a matter of design. Will to implement this syntax or not.
If not, this would be a feature request.

Error handling is still in its infancy.
Any technically feasible improvements that will make it more useful should be made proactively.
I do not believe that the status quo is the right way to go.

Thanks to their progressive attitude, the current match statement is so much easier to use than it was two years ago.

It would be great to see the same progressive attitude and improvement with regard to error handling.

Same concept as

fn bar() !string{
	return error('')
}

fn foo() !{
	s := match true {
		true { 'a' }
		else { bar()! }
	}
	println(s)
}

[ghost]

fn foo() !{
	s := match true {
		true { 'a' }
		else { '' }
	}

	if s == '' { return error('') }
	println(s)
}

One of the problems of this code is when match returns a structure, although I used a string for simplicity in above example.
Nil or null defined struct?
If errors can be returned within match, this can be avoided.