Use the logical or operator, not the logical and operator (consider what the cmp and <=> operators return!).

Also, you could split once per string per sort. Or, better (for performance, though not necessarily for memory usage), use a Schwartzian transform so you only split once per string:

@bar = map {
  $$_[0]
} sort {
  $$a[1] <=> $$b[1] ||
  $$a[2] <=> $$b[2] ||
  $$a[3] <=> $$b[3]
} map {
  [$_, split/-/]
} @foo;
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This also helps keep the "what I'm splitting" and "what I'm sorting" code clear by separating them.