The rule in Perl is simple. Where every you write $variable, @variable, %variable, &variable or *variable, you may replace variable with a block whose value is a reference of the appropriate type.

So, in your case, you want to write something like

    foreach (@array) { ... }
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but you don't have an array, just a reference to one ($sort -> {column} being the reference). So, you would write:

    foreach (@{$sort -> {column}}) { ... }
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Abigail