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Folding of Single-Field Structs

In JSON, one defines nested values, one value at a time. Another way to look at this is that a JSON configuration is a set of path-value pairs.

In CUE one defines a set of paths to which to apply a concrete value or constraint all at once. Because or CUE’s order independence, values get merged

This example shows some path-value pairs, as well as a constraint that is applied to those to validate them.

fold.cue

// path-value pairs
outer: middle1: inner: 3
outer: middle2: inner: 7

// collection-constraint pair
outer: [string]: inner: int

$ cue export fold.cue

{
    "outer": {
        "middle1": {
            "inner": 3
        },
        "middle2": {
            "inner": 7
        }
    }
}