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Comment by tsukaisute | Hacker News Reader

Because with more expressive constructs, you may find not having to write list[ix] very often. For example, a traditional "for" loop may be replaced more succinctly with an operation such as "Enum.map" or "Enum.filter" [1]. Data transformations made more obvious.

Coming from imperative languages especially (speaking for myself), have to re-think/re-learn how you write code, but it does end up being a worthwhile investment

[1] https://hexdocs.pm/elixir/Enum.html

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I want to beleive that, but I don't know. For example, in Elixir, you would write something like this to square a list: 'Enum.map [1,2,3], $($1 * $1)'. In Ruby: '[1,2,3].map {|e| e * e}'. The Ruby seems more natural to me, but maybe it's the years of OOP speaking and not reason.

Ive been studying functional languages for the most part of 2017 and the first example makes more sense to me.

Btw, there are a number of ways to write that expression depending on the complexity of the function

Short syntax:

   Enum.map [1,2,3], &(&1 * &1)

Long syntax:

   Enum.map [1,2,3], (fn num ->
     num * num
   end)

Or even:

   square_me = &(&1 * &1)
   Enum.map [1,2,3], square_me

   square_me_too = fn(num) -> num * num end
   Enum.map [1,2,3], square_me_too

Defining a function separately (e.g. even in another module) and referencing it:

   def square(num) do
      num * num
   end

   def doing_something() do
      ...

      Enum.map [1,2,3], &square/1
      Enum.map [1,2,3], &SomeOtherModule.square/1

      ...
   end

yeah and in Ruby, you can do:

    class Array
      def square
        map {|e| e * e}
      end
    end

Why storing code in a seperate module is a superior way than storing code in its class?

You've now altered a global object which other code may rely on. Indeed, you may overwrite someone else's Array#square method (or have yours overwritten). As a separate module, the additional code is logically distinct. You can find many discussions about monkey-patching elsewhere. It's not my intent here to argue one way or the other, just to answer your question as to why one may choose package the code as a separate module.

If it is to be reused by other modules, or if it is complex (and likely itself needs to be split up into smaller functions)

Think of:

   items = ["file_a", "file_b", "file_c"]
   Enum.map items, &HelpfulDownloaderModule.download/1

download/1 is probably pretty complex and/or can be of use in other pieces of code.

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