Definitions

A definition, indicated by an identifier starting with # or _#, defines values that are not output when converting a configuration to a concrete value. They are used to define schema against which concrete values can be validated.

Structs defined by definitions are implicitly closed.

msg: "Hello \(#Name)!"

#Name: "world"

#A: {
    field: int
}

a:   #A & { field: 3 }
err: #A & { feild: 3 }

msg: "Hello world!"
a: {
    field: 3
}
err: _|_ // field "feild" not allowed in closed struct