Ruby: merge multiple hashes

Before:

{a: 1}.merge(b: 2).merge(c: 3).merge(d: 4)

Now, you can use inject or reduce:

[{a: 1}, {b: 2}, {c: 3}, {d: 4}].inject(:merge)

=> {:a=>1, :b=>2, :c=>3, :d=>4}