Should references to a sequence be possible?

[akaIDIOT]

References are allowed to an entire subtree, but should that be possible in a sequence? Something like

blah: ${data[1].key}
data:
  - key: value
    another_key: blah
  - key: second value

where config.blah would resolve to value 'second value'.

Parsing the reference wouldn't be too hard, recursive references wouldn't even be a problem, but would this hurt anywhere?