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Lists

Lists define arbitrary sequences of CUE values. A list can be closed or open ended. Open-ended lists may have some predefined elements, but may have additional, possibly typed elements.

In the example we define IP to be a list of 4 elements of type uint8, which is a predeclared value of >=0 & <=255. PrivateIP defines the IP ranges defined for private use. Note that as it is already defined to be an IP, the length of the list is already fixed at 4 and we do not have to specify a value for all elements. Also note that instead of writing ...uint8, we could have written ... as the type constraint is already already implied by IP.

The output contains a valid private IP address (myIP) and an invalid one (yourIP).

lists.cue

IP: 4 * [ uint8 ]

PrivateIP: IP
PrivateIP: [10, ...uint8] |
    [192, 168, ...] |
    [172, >=16 & <=32, ...]

myIP: PrivateIP
myIP: [10, 2, 3, 4]

yourIP: PrivateIP
yourIP: [11, 1, 2, 3]

$ cue eval -i lists.cue

IP: [uint8, uint8, uint8, uint8]
PrivateIP: [10, uint8, uint8, uint8] | [192, 168, uint8, uint8] | [172, >=16 & <=32 & uint8, uint8, uint8]
myIP: [10, 2, 3, 4]
yourIP: _|_ // ; empty disjunction: conflicting values 192 and 11; empty disjunction: conflicting values 172 and 11