I understand. I'll scrap this branch then.
Here are the implementations (if there is any feedback, I'd like to hear it
even if it won't be included):
@spec replace_many(map, keyword) :: map
def replace_many(map, pairs) when is_list(pairs) do
replace_pairs(map, pairs, map)
end
defp replace_pairs(map, [], _original), do: map
defp replace_pairs(map, [{key, value} | pairs], original) do
case original do
%{^key => _} -> replace_pairs(%{map | key => value}, pairs, original)
%{} -> raise KeyError, key: key, term: original
other -> :erlang.error({:badmap, other})
end
end
@spec update_many(map, [atom | String.t()], (existing_value :: value ->
new_value :: value)) :: map
def update_many(map, keys, fun) when is_list(keys) and is_function(fun,
1) do
update_keys(map, keys, fun, map)
end
defp update_keys(map, [], _fun, _original), do: map
defp update_keys(map, [key | keys], fun, original) do
case original do
%{^key => value} -> update_keys(%{map | key => fun.(value)}, keys,
fun, original)
%{} -> raise KeyError, key: key, term: original
other -> :erlang.error({:badmap, other})
end
end
______________________________________________________________________________________________________________________________________
@spec replace_many(keyword, keyword) :: keyword
def replace_many(keywords, pairs) when is_list(pairs) do
replace_pairs(keywords, pairs, keywords)
end
defp replace_pairs(keywords, [], _original), do: keywords
defp replace_pairs(keywords, [{key, value} | pairs], original) do
replace_pairs(replace!(keywords, key, value, original), pairs, original)
end
@spec update_many(keyword, [atom], (existing_value :: value -> new_value
:: value)) :: keyword
def update_many(keywords, keys, fun) when is_list(keys) and
is_function(fun) do
update_keys(keywords, keys, fun, keywords)
end
defp update_keys(keywords, [], _fun, _original), do: keywords
defp update_keys(keywords, [key | keys], fun, original) do
update_keys(update!(keywords, key, fun, original), keys, fun, original)
end
Would you also mind directing me to where I can find the implementation of
%{map
| key => value}? I wasn't able to find it and I'm very curious as to how it
works under-the-hood.
On Friday, December 31, 2021 at 4:43:00 PM UTC-5 José Valim wrote:
> Thank you for sharing!
>
> Can you please share the implementations too? But generally speaking, I
> don’t think the performance difference is relevant enough to justify the
> inclusion.
>
> On Fri, Dec 31, 2021 at 21:40 Paul Alexander <paul.aj...@gmail.com> wrote:
>
>> I believe this is easier to read/follow:
>>
>> Name ips average deviation
>> median 99th %
>>
>> map replace_many 1.93 M 517.77 ns ±9182.17% 0
>> ns 1000 ns
>>
>> map reduce + replace! 1.58 M 631.47 ns ±7266.46% 0
>> ns 2000 ns
>>
>> map for + replace 1.58 M 634.43 ns ±8194.35% 0
>> ns 2000 ns
>>
>> Comparison:
>>
>> map replace_many 1.93 M
>>
>> map reduce + replace! 1.58 M - 1.22x slower +113.70 ns
>>
>> map for + replace 1.58 M - 1.23x slower +116.66 ns
>>
>>
>> Name ips average deviation
>> median 99th %
>>
>> map update_many 1.43 M 701.44 ns ±7768.55% 0
>> ns 2000 ns
>>
>> map for + update! 1.20 M 832.54 ns ±5683.86% 1000
>> ns 2000 ns
>>
>> map reduce + update! 1.17 M 851.53 ns ±4816.16% 1000
>> ns 2000 ns
>>
>> Comparison:
>>
>> map update_many 1.43 M
>>
>> map for + update! 1.20 M - 1.19x slower +131.09 ns
>>
>> map reduce + update! 1.17 M - 1.21x slower +150.08 ns
>>
>>
>> Name ips average deviation
>> median 99th %
>>
>> keywords replace_many 1.49 M 669.04 ns ±5836.31%
>> 980 ns 1980 ns
>>
>> keywords reduce + replace! 1.41 M 710.24 ns ±5503.07%
>> 980 ns 1980 ns
>>
>> keywords for + replace! 1.40 M 714.06 ns ±5791.74%
>> 980 ns 1980 ns
>>
>> Comparison:
>>
>> keywords replace_many 1.49 M
>>
>> keywords reduce + replace! 1.41 M - 1.06x slower +41.19 ns
>>
>> keywords for + replace! 1.40 M - 1.07x slower +45.02 ns
>>
>>
>> Name ips average deviation
>> median 99th %
>>
>> keywords update_many 1.35 M 742.22 ns ±5371.88%
>> 1000 ns 2000 ns
>>
>> keywords reduce + update! 1.02 M 976.57 ns ±5363.65%
>> 1000 ns 2000 ns
>>
>> keywords for + update! 1.01 M 986.09 ns ±5456.16%
>> 1000 ns 2000 ns
>>
>> Comparison:
>>
>> keywords update_many 1.35 M
>>
>> keywords reduce + update! 1.02 M - 1.32x slower +234.34 ns
>>
>> keywords for + update! 1.01 M - 1.33x slower +243.87 ns
>>
>>
>> Does this sway your opinion on the proposal, José?
>> On Friday, December 31, 2021 at 12:29:00 PM UTC-5 Paul Alexander wrote:
>>
>>> Thank you, Marten, for the suggestion. And Happy New Year!
>>> I actually ended up doing that before your reply, except I had used a
>>> "homebrew benchmarking" implementation. I also did it with Benchee, and the
>>> results really weren't all that different but I've included only the
>>> results from Benchee below.
>>>
>>> Name ips average deviation
>>> median 99th %
>>>
>>> map replace_many 2.69 M 371.13 ns ±10368.06%
>>> 0 ns 990 ns
>>>
>>> map for + replace 2.32 M 430.38 ns ±8111.30%
>>> 0 ns 990 ns
>>>
>>> map reduce + replace! 2.32 M 431.63 ns ±8167.48%
>>> 0 ns 990 ns
>>>
>>> map update_many 2.05 M 488.47 ns ±9258.19%
>>> 0 ns 990 ns
>>>
>>> map for + update! 1.64 M 609.13 ns ±5804.57%
>>> 0 ns 990 ns
>>>
>>> map reduce + update! 1.66 M 600.64 ns ±5698.26%
>>> 0 ns 990 ns
>>>
>>> keywords replace_many 1.91 M 523.22 ns ±6849.81%
>>> 0 ns 990 ns
>>>
>>> keywords for + replace! 1.84 M 544.19 ns ±6432.10%
>>> 0 ns 990 ns
>>>
>>> keywords reduce + replace! 1.82 M 550.39 ns ±6488.68%
>>> 0 ns 990 ns
>>>
>>> keywords update_many 1.78 M 561.74 ns ±6508.52%
>>> 0 ns 990 ns
>>>
>>> keywords for + update! 1.49 M 670.96 ns ±6347.76%
>>> 0 ns 990 ns
>>>
>>> keywords reduce + update! 1.46 M 686.43 ns ±6250.71%
>>> 0 ns 990 ns
>>>
>>>
>>> On Friday, December 31, 2021 at 2:05:17 AM UTC-5 w...@resilia.nl wrote:
>>>
>>>> Putting them in a module in any file (with e.g. a `.ex` or `.exs`
>>>> extension) and running them from there will work.
>>>> You might also like to look into libraries such as `Benchee` which make
>>>> benchmarking easier and prevent some of the pitfalls which a homebrew
>>>> benchmarking implementation might have.
>>>>
>>>> Hope this helps, and happy old year/new year :-),
>>>>
>>>> ~Marten
>>>> On 31-12-2021 01:01, Paul Alexander wrote:
>>>>
>>>> Sorry. Would putting them in a test case be better practice? If not, do
>>>> you mind telling me of the correct way which would produce the most
>>>> indicative results?
>>>>
>>>> On Thursday, December 30, 2021 at 6:24:08 PM UTC-5 José Valim wrote:
>>>>
>>>>> Don’t benchmark in the shell. Code in the shell is evaluated and not
>>>>> compiled.
>>>>>
>>>>> On Fri, Dec 31, 2021 at 00:14 Paul Alexander <paul.aj...@gmail.com>
>>>>> wrote:
>>>>>
>>>>>> Thanks for offering your opinion, José. I very much understand where
>>>>>> you're coming in regards to using Enum.reduce/3 for such an operation,
>>>>>> but
>>>>>> I have found it to cause a fair amount of needless overhead especially
>>>>>> when
>>>>>> there are other operations going on and the updating should be the most
>>>>>> trivial. Since you brought up the efficiency tradeoffs, I've put
>>>>>> together a
>>>>>> few simple benchmarks below for the Map functions where the results are
>>>>>> from averaging 10k iterations. As you can see the performance
>>>>>> improvement
>>>>>> is quite drastic, with both *_many functions being 130%+ .
>>>>>>
>>>>>> iex> map
>>>>>>
>>>>>> %{a: 1, b: 2, c: 3, d: 4, e: 5, f: 6, g: 7, h: 8, i: 9, j: 10}
>>>>>>
>>>>>> iex> kv
>>>>>>
>>>>>> [a: 11, d: 22, g: 33, j: 44]
>>>>>>
>>>>>> iex> keys
>>>>>>
>>>>>> [:a, :d, :g, :j]
>>>>>>
>>>>>> iex(32)> Benchmark.measure(10_000, "reduce + replace!", fn ->
>>>>>> Enum.reduce(kv, map, fn {k, v}, acc -> Map.replace!(acc, k, v) end) end)
>>>>>>
>>>>>> reduce + replace! avg: 18.2396
>>>>>>
>>>>>> iex(33)> Benchmark.measure(10_000, "replace_many", fn ->
>>>>>> Map.replace_many(map, kv) end)
>>>>>>
>>>>>> replace_many avg: 1.0979
>>>>>>
>>>>>> iex(34)> Benchmark.measure(10_000, "reduce + update!", fn ->
>>>>>> Enum.reduce(keys, map, fn k, acc -> Map.update!(acc, k, &(&1*2)) end)
>>>>>> end)
>>>>>>
>>>>>> reduce + update! avg: 48.284
>>>>>>
>>>>>> iex(35)> Benchmark.measure(10_000, "update_many", fn ->
>>>>>> Map.update_many(map, keys, &(&1*2)) end)
>>>>>>
>>>>>> update_many avg: 9.8719
>>>>>> On Thursday, December 30, 2021 at 5:13:10 PM UTC-5 José Valim wrote:
>>>>>>
>>>>>>> Hi Paul,
>>>>>>>
>>>>>>> Thanks for the proposal. My personal take is that a Enum.reduce/3 +
>>>>>>> the relevant Map operation should be the way to go, because this can
>>>>>>> easily
>>>>>>> lead to a combination of replace_many, update_many, put_new_many, etc.
>>>>>>> Especially because the many operations likely wouldn't be any more
>>>>>>> efficient than the Enum.reduce/3 call.
>>>>>>>
>>>>>>>
>>>>>>> On Thu, Dec 30, 2021 at 10:42 PM Paul Alexander <
>>>>>>> paul.aj...@gmail.com> wrote:
>>>>>>>
>>>>>>>> Hi everyone,
>>>>>>>>
>>>>>>>> I would like to discuss the possibility of adding two new functions
>>>>>>>> to each of the Map and Keyword modules; replace_many/2 and
>>>>>>>> update_many/3.
>>>>>>>> Their purpose is to update maps and keyword lists providing either a
>>>>>>>> keyword list of the key-value pairs which need to updated, or a list
>>>>>>>> of
>>>>>>>> keys and a function which operates on the existing values of those
>>>>>>>> keys.
>>>>>>>>
>>>>>>>> Far too often I find myself needing to call replace!/3 or update!/3
>>>>>>>> several times from within a pipeline, or even needing to use a
>>>>>>>> for-comprehension or Enum.reduce/3 to update a map in "one shot", when
>>>>>>>> it
>>>>>>>> feels like there should be a function for this.
>>>>>>>>
>>>>>>>> There are a number of reasons as to why I think these functions
>>>>>>>> should be considered, but I'll provide only two for now:
>>>>>>>>
>>>>>>>> 1. There is already a way of updating multiple key-value pairs
>>>>>>>> simultaneously for maps using %{map | k1 => v1, k2 => v2}. But this
>>>>>>>> unfortunately does not support passing a literal keyword list after
>>>>>>>> the
>>>>>>>> cons operator.
>>>>>>>> - My first instinct was to see if I could expand the special
>>>>>>>> update syntax to handle keyword lists, but I wasn't able to find
>>>>>>>> where it
>>>>>>>> is in the codebase. If someone could point that out for me
>>>>>>>> because I'd like
>>>>>>>> to learn how it works, I'd greatly appreciate it.
>>>>>>>> 2. It would be somewhat analogous to Kernel.struct!/2, where
>>>>>>>> keyword lists can be passed as the second argument to update
>>>>>>>> several fields
>>>>>>>> within a struct. Seeing as how structs are maps, it only makes
>>>>>>>> sense there
>>>>>>>> should be a way that maps could be updated in a similar manner from
>>>>>>>> within
>>>>>>>> the Map module.
>>>>>>>>
>>>>>>>>
>>>>>>>> I have already implemented the four functions, complete with docs,
>>>>>>>> examples, and passing tests. But I wanted confirmation from the core
>>>>>>>> team
>>>>>>>> if a PR is welcome for this addition. Any opinions?
>>>>>>>>
>>>>>>> --
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