Elixir - Witchcraft

• style guide

style guide

using Witchcraft operator aliases (say, >>>/2 instead of chain/2) has a few drawbacks:

• you’ve got to wrap captured named functions in parentheses

  %Algae.Either.Right{right: 5}
  ~> (&foo/1) # <--- it's required to wrap it in parens
  |> bar()
  

  otherwise unwrapped data is passed down the chain: say, if foo/1 returns 10, for some reason it’s passed as is to bar/1 while it must be wrapped in container (%Algae.Either.Right{right: 10}) - this is how Functor.lift/2 is meant to work.

  NOTE: it’s okay to use anonymous functions without parentheses:

  %Algae.Either.Right{right: 5}
  ~> fn x -> x + 1 end # <--- no need to wrap it in parens
  |> bar()
  

• Credo complains that pipe chain doesn’t start with a raw value (Credo.Check.Refactor.PipeChainStart check)

  %Algae.Either.Right{right: 5}
  ~> (&foo/1)
  |> bar() # <--- Credo reports issue for this line
  

  however Credo doesn’t complain if pipe operator is not used after Witchcraft operator aliases:

  ```elixir %Algae.Either.Right{right: 5} ~> (&foo/1) ~> (&bar/1)

• Elixir formatter doesn’t play well with some operators

  consider this code:

  %Algae.Either.Right{right: 5}
  >>> (&foo/1)
  ~> bar()
  

  and this is how it’s formatted:

  %Algae.Either.Right{right: 5} >>>
    (&foo/1)
  ~> bar()
  

  maybe it’s because Elixir has built-in Bitwise.>>>/2 operator.

as a result I see no other way but to refrain from using Witchcraft operator aliases at all except for few cases:

• ~> operator alias can be used with anonymous functions at the end of the pipe
• all operator aliases can be used without pipe or when statement doesn’t spread across multiple lines