The thing with `x_by` functions is that they still return the whole list (like in `sort_by`) or an element of it (like in `max_by`).
Example right from `h Enum.max_by`: ```elixir iex> Enum.max_by(["a", "aa", "aaa"], fn(x) -> String.length(x) end) "aaa" ``` `Enum.sum` totally changes the returning value type to another, so I guess there is no point of having them since you can totally use the function `map` on your enumerable to get what you want. For example: ```elixir iex> [“a”, “aa”, “aaa”] |> Stream.map(&String.length/1) |> Enum.sum() => 6 ``` Best, Kelvin Stinghen [email protected] > On Feb 2, 2018, at 05:48, Alexey Chernenkov <[email protected]> wrote: > > I'm missing `Enum.sum_by/2` func. There are several other `xxx_by` methods > (e.g. `sort_by` and `max_by`). > > -- > You received this message because you are subscribed to the Google Groups > "elixir-lang-core" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] > <mailto:[email protected]>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/elixir-lang-core/f7c51011-5ff4-4667-8125-75ced517887a%40googlegroups.com > > <https://groups.google.com/d/msgid/elixir-lang-core/f7c51011-5ff4-4667-8125-75ced517887a%40googlegroups.com?utm_medium=email&utm_source=footer>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. -- You received this message because you are subscribed to the Google Groups "elixir-lang-core" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/elixir-lang-core/7D23AA55-92B7-4EAA-A062-09F6493C73C5%40gmail.com. For more options, visit https://groups.google.com/d/optout.
