[ruby-core:119389] [Ruby master Feature#20770] A *new* pipe operator proposal

["zverok (Victor Shepelev) via ruby-core" <ruby-core@ml.ruby-lang.org>]

Issue #20770 has been updated by zverok (Victor Shepelev).


@Eregon this example (at least for me) is just an easy target for discussion (because it uses standard libraries, is easily reproducible, and demonstrates the multi-step realistic process that uses several libraries at once).

I believe the point here is not “how it could be rewritten in non-flow-style,” but rather “many people in many codebases find flow-style useful, should we have a syntax sugar for it?”

I can confirm that for me (and many colleagues who were exposed to this style), it seems a more convenient way, especially to structure business code or quick sketching. It also might have a positive effect on overall algorithm structuring: the code author starts to think in “sequence of steps” terms, and (again, especially in complicated business code developed rapidly) it provides some protection against messy methods, where many local variables are calculated, and soon it is hard to tell which of them related to which of the next steps and how many flows are there.

I think it is also very natural to Ruby, considering one of the things we have different than many other languages is Enumerable as the center cycle structure, which supports chains of sequence transformations... So, `then` is just a chain of singular value transformations.

But I think it is not necessary to prefer this style yourself to acknowledge others find it useful. (Well, alternatively, it could be a discussion like “nobody should do that, it shouldn’t be preferred/supported style,” but that’s another discussion.)

----------------------------------------
Feature #20770: A *new* pipe operator proposal
https://bugs.ruby-lang.org/issues/20770#change-110006

* 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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