Merge deeply nested hashes faster than DeepMerge or ActiveSupport.
Install the gem and add to the application's Gemfile by executing:
bundle add sin_deep_mergeIf bundler is not being used to manage dependencies, install the gem by executing:
gem install sin_deep_mergeSinDeepMerge's Hash#deep_merge is compatible with ActiveSupport's Hash#deep_merge.
require 'sin_deep_merge'
hash1 = { a: 1, b: '2', c: :three, d: true, e: nil }
hash2 = { b: :two, c: nil, d: false, e: 0, f: 'f' }
hash1.deep_merge(hash2) # => { a: 1, b: :two, c: nil, d: false, e: 0, f: 'f' }
hash1 = { a: [1, 2], b: [3, 4] }
hash2 = { a: [3, 4], b: 5 }
hash1.deep_merge(hash2) # => { a: [3, 4], b: 5 }
hash1 = { a: { b: 1, c: 2 }, b: { c: 3 } }
hash2 = { a: { c: 3, d: 4 }, b: 5 }
hash1.deep_merge(hash2) # => { a: { b: 1, c: 3, d: 4 }, b: 5 }
hash1 = { a: 1, b: 2 }
hash2 = { b: 3, c: 4 }
hash1.deep_merge(hash2) { |_key, old_val, new_val| old_val + new_val } # => { a: 1, b: 5, c: 4 }
hash1 = { a: [1, 2], b: 3 }
hash2 = { a: [3, 4], b: 5 }
hash1.deep_merge(hash2) do |_key, old_val, new_val|
if old_val.is_a?(Array) && new_val.is_a?(Array)
old_val + new_val
else
new_val
end
end # => { a: [1, 2, 3, 4], b: 5 }Hash#deep_merge! destructively updates self by merging new values directly into it.
SinDeepMerge's Hash#deep_merge is about 1.5-1.7x faster than ActiveSupport's Hash#deep_merge and about 3.6-5.3x faster than DeepMerge's Hash#deep_merge.
$ bundle exec rake benchmark
+-----------------------------------------------------------------+
| Benchmark Result (Shallow Recursion) |
+----------------------------+----------------------+-------------+
| Name | Iteration Per Second | Speed Ratio |
+----------------------------+----------------------+-------------+
| SinDeepMerge - deep_merge | 1899218.6 | - |
| Scratch - deep_merge | 1289196.4 | 1.5x slower |
| ActiveSupport - deep_merge | 1215659.6 | 1.6x slower |
| DeepMerge - deep_merge | 358813.8 | 5.3x slower |
+----------------------------+----------------------+-------------+
+-----------------------------------------------------------------+
| Benchmark Result (Shallow Recursion With Block) |
+----------------------------+----------------------+-------------+
| Name | Iteration Per Second | Speed Ratio |
+----------------------------+----------------------+-------------+
| SinDeepMerge - deep_merge | 1594873.2 | - |
| Scratch - deep_merge | 1235536.5 | 1.3x slower |
| ActiveSupport - deep_merge | 1062621.4 | 1.5x slower |
| DeepMerge - deep_merge | 356335.5 | 4.5x slower |
+----------------------------+----------------------+-------------+
+-----------------------------------------------------------------+
| Benchmark Result (Deep Recursion) |
+----------------------------+----------------------+-------------+
| Name | Iteration Per Second | Speed Ratio |
+----------------------------+----------------------+-------------+
| SinDeepMerge - deep_merge | 23017.8 | - |
| ActiveSupport - deep_merge | 14626.7 | 1.6x slower |
| Scratch - deep_merge | 14271.6 | 1.6x slower |
| DeepMerge - deep_merge | 6277.8 | 3.7x slower |
+----------------------------+----------------------+-------------+
+-----------------------------------------------------------------+
| Benchmark Result (Deep Recursion With Block) |
+----------------------------+----------------------+-------------+
| Name | Iteration Per Second | Speed Ratio |
+----------------------------+----------------------+-------------+
| SinDeepMerge - deep_merge | 22727.1 | - |
| Scratch - deep_merge | 14154.0 | 1.6x slower |
| ActiveSupport - deep_merge | 13661.2 | 1.7x slower |
| DeepMerge - deep_merge | 6279.9 | 3.6x slower |
+----------------------------+----------------------+-------------+The benchmark was executed in the following environment:
ruby 3.4.2 (2025-02-15 revision d2930f8e7a) +YJIT +PRISM [arm64-darwin24]
See CHANGELOG.md.
Bug reports and pull requests are welcome on GitHub at https://github.com/cadenza-tech/sin_deep_merge. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.
The gem is available as open source under the terms of the MIT License.
Everyone interacting in the SinDeepMerge project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.
You can sponsor this project on Patreon.
