From: "shuber (Sean Huber) via ruby-core" <ruby-core@...>
Date: 2024-10-02T15:19:06+00:00
Subject: [ruby-core:119405] [Ruby master Feature#20770] A *new* pipe operator proposal

Issue #20770 has been updated by shuber (Sean Huber).


I agree with @zverok and am not quite sold on the value of `|>` over the existing `.then{}` if we still have to explicitly specify implicit args like `it/_1/etc` (unlike elixir).

I am intrigued by the `.{}` syntax though but wish it did more than behave as an alias for `.then{}`.

What if `.{}` behaved more like this elixir-style syntax without implicit args?

```ruby
# existing ruby syntax

url
  .then { URI.parse(it) }
  .then { Net::HTTP.get(it) }
  .then { JSON.parse(it).fetch_keys("some", "keys") }
  .then { JSON.pretty_generate(it, allow_nan: false) }
  .then { Example.with_non_default_arg_positioning(other_object, it) }

# proposed ruby syntax

url
  .{ URI.parse }
  .{ Net::HTTP.get }
  .{ JSON.parse.fetch_keys("some", "keys") }
  .{ JSON.pretty_generate(allow_nan: false) }
  .{ Example.with_non_default_arg_positioning(other_object, self) }
```


----------------------------------------
Feature #20770: A *new* pipe operator proposal
https://bugs.ruby-lang.org/issues/20770#change-110020

* 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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