Julia does not permit such syntax but what I want is basically

```
struct A{T, 2}
x::T
y::T
end
struct A{T, 3}
x::T
y::T
z::T
end
struct A{T, 4}
x::T
y::T
z::T
w::T
end
```

i.e., the number in type parameter matches the number of fields. The fields could contain `x, y, z, w, a, b, c, d...`

, and so on.

Is there a way of doing this?