From: "austin (Austin Ziegler) via ruby-core" <ruby-core@...>
Date: 2024-11-08T19:29:44+00:00
Subject: [ruby-core:119850] [Ruby master Feature#20770] A *new* pipe operator proposal

Issue #20770 has been updated by austin (Austin Ziegler).


lpogic (��ukasz Pomiet��o) wrote in #note-36:
> What if I need an intermediate result beyond the next step of the method chain?
> 
> Cases:
> ``` ruby
> def foo
>   r |> q(_) |> p(_)
>   return q_result  # "q_result" should be the result of the second step of the chain
> end
> ```
> 
> ``` ruby
> def foo
>   r |> q(_) |> p(_, r_result) # "r_result" should be the result of the first step of the chain
> end
> ```

If you need an intermediate result for any reason, don't use a pipeline, or restructure your return values so that they are returning some sort of context object. In your examples, `#tap` and `#then` would be more useful:

```ruby
def foo
  q(r).tap { p(_1) }
end

def bar
  r
    .then { [_1, q(_1) }
    .then { |(rr, qr)| p(qr, rr) }
end

def baz
  rr = r
  p(q(rr), rr)
end
```

I use the pipe operator in Elixir extensively, but I don't think that I���ve seen a proposal that would really improve Ruby's syntax over `.then { ��� }` *except* the proposed `.{}` acting as syntax sugar for `.then {���}`.

----------------------------------------
Feature #20770: A *new* pipe operator proposal
https://bugs.ruby-lang.org/issues/20770#change-110541

* Author: AlexandreMagro (Alexandre Magro)
* Status: Open
----------------------------------------
Hello,

This is my first contribution here. I have seen previous discussions around introducing a pipe operator, but it seems the community didn't reach a consensus. I would like to revisit this idea with a simpler approach, more of a syntactic sugar that aligns with how other languages implement the pipe operator, but without making significant changes to Ruby's syntax.

Currently, we often write code like this:

```ruby
value = half(square(add(value, 3)))
```

We can achieve the same result using the `then` method:

```ruby
value = value.then { add(_1, 3) }.then { square(_1) }.then { half(_1) }
```

While `then` helps with readability, we can simplify it further using the proposed pipe operator:

```ruby
value = add(value, 3) |> square(_1) |> half(_1)
```

Moreover, with the upcoming `it` feature in Ruby 3.4 (#18980), the code could look even cleaner:

```ruby
value = add(value, 3) |> square(it) |> half(it)
```

This proposal uses the anonymous block argument `(_1)`, and with `it`, it simplifies the code without introducing complex syntax changes. It would allow us to achieve the same results as in other languages that support pipe operators, but in a way that feels natural to Ruby, using existing constructs like `then` underneath.

I believe this operator would enhance code readability and maintainability, especially in cases where multiple operations are chained together.

Thank you for considering this proposal!






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