While writing Elixir, you are encouraged to start your pipe chain with a raw value. Credo has a check for this at credo/lib/credo/check/refactor/pipe_chain_start.ex at master · rrrene/credo · GitHub

However, I think blindly applying this decreases the readability of the code. Here are a few examples:

Instances where this rule makes sense

# 1
 list
      |> Enum.take(5)
      |> Enum.shuffle
      |> pick_winner()

#2
      %User{}
      |> User.changeset(%{"email" => "danny@m.com"})
      |> Repo.insert()

Instances where this rule does not make sense

# 3
User
    |> Repo.all
    |> Enum.map(fn(user) -> csv_fields(user) end)
    |> CSV.encode(headers: true)


#4
    20
    |> :crypto.strong_rand_bytes
    |> Base.encode16(case: :lower)

I think the question boils down to whether you are transforming something. In case of 20 |> :crypto.strong_rand_bytes you are not really transforming 20 into bytes and instead getting 20 random bytes. Just because it is an argument to a function doesn’t mean it is being transformed. What are your thoughts on this?

After writing this, I looked if there was similar discussion elsewhere and found Proposal: Ignore refactoring opportunities in pipe chain when using erlang functions · Issue #14 · rrrene/credo-proposals · GitHub