named parameter support when destructureing from the constructor

[seebees]

given

datatype Foo = Foo(
  nameonly Bar: nat
)

I can var f := Foo( Bar: 5 );
I can also var Foo(b) := f;

I want to be able to use the named parameter.
Something like
var Foo(b := Bar) := f; or var Foo(bar -> b) := f;

[MikaelMayer]

I agree, that would make even possible to use partial matches where you don't need an pattern argument for every parameter.