doc/tutorial/basics/unification.md

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_Types ~~and~~ are Values_

# Order is Irrelevant

As mentioned before, values of duplicates fields are combined.
This process is called unification.
Unification can also be written explicitly with the `&` operator.

There is always a single unique result, possibly bottom,
for unifying any two CUE values.

Unification is commutative, associative, and idempotent.
In other words, order doesn't matter and unifying a given set of values
in any order always gives the same result.

<!-- CUE editor -->
_unification.cue:_
```
a: { x: 1, y: 2 }
b: { y: 2, z: 3 }
c: { x: 1, z: 4 }

q: a & b & c
r: b & c & a
s: c & b & a
```

<!-- result -->
`$ cue eval -i unification.cue`
```
a: {
    x: 1
    y: 2
}
b: {
    y: 2
    z: 3
}
c: {
    x: 1
    z: 4
}
q: {
    x: 1
    y: 2
    z: _|_ /* conflicting values: 3 != 4 */
}
r: {
    x: 1
    y: 2
    z: _|_ /* conflicting values: 3 != 4 */
}
s: {
    x: 1
    y: 2
    z: _|_ /* conflicting values: 4 != 3 */
}
```