Closing toplevel value

[istvan-andrasi]

Hi! I wanted to only allow fields matching a regex at the toplevel, and I tried this:

package tmp

#Top
#Top: [=~"^[A-Z_]+$"]: {...}

OK: {}
nok: {}

I expected it to fail, but it works:

> cue eval
#Top: {}
OK: {}
nok: {}

A assumed (and verified) it is because:

#Top     // is actually equivalent to
{ #Top } // which is embedding, thus allowing other fields

Although I found a workaround:

package tmp

[=~"^[A-Z_]+$"]: {...}
[!~"^[A-Z_]+$"]: _wrong_name: true & false

OK: {}
nok: {}

> cue eval
nok._wrong_name: conflicting values false and true:
    ./tmp.cue:7:22
    ./tmp.cue:7:35
    ./tmp.cue:7:42

I wanted to bring up if it would be sensible to treat closed toplevel struct references differently:

#Top     // would mean <toplevel>: #Def
{ #Top } // would mean <toplevel>: { #Def }

What do you think?