# Record is a feature similar to object (literal notation) in JS
# `.` means the field is public
john = {
    .name = "John Smith"
    .age = !27
}

assert john.name == "John Smith"
assert john.age == 27
john.age.update! old -> old + 1
assert john.age == 28
# Record is not Dict, so `john["name"]` is invalid

# A record whose values are all types will also behave as a type
Person! = {
    .name = Str
    .age = Nat!
}

assert Person!.age == Str
assert john in Person!