From: "mame (Yusuke Endoh) via ruby-core" <ruby-core@...>
Date: 2024-10-01T07:11:53+00:00
Subject: [ruby-core:119373] [Ruby master Feature#20770] A *new* pipe operator proposal

Issue #20770 has been updated by mame (Yusuke Endoh).


When pipeline operator was proposed previously (#15799), we briefly spoke of the idea of a block notation without a closing bracket ([the meeting log](https://github.com/ruby/dev-meeting-log/blob/c908bf7e7be60af5c5feabb544541de5f7d003ef/2019/DevMeeting-2019-06-13.md?plain=1#L225)).

For example,

```
add(value, 3).then do |x|> square(x)
```

is interpreted as:

```
add(value, 3).then {|x| square(x) }
```

However, this notation is a bit outlandish, so it was never taken very seriously.

Reconsidering it with the notation proposed in this ticket:

```
add(value, 3).then |> square(it).then |> half(it)
```

is handled as:

```
add(value, 3).then { square(it).then { half(it) } } # Or:
add(value, 3).then { square(it) }.then { half(it) } # depending on the associativity of |>. I am not sure which is better
```

It might be a good idea that we specialize this notation only for a block that is so simple that we don't need to name the parameters.

But personally, I also feel that:

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

is good enough.

----------------------------------------
Feature #20770: A *new* pipe operator proposal
https://bugs.ruby-lang.org/issues/20770#change-109989

* 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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