---
source: crates/biome_formatter_test/src/snapshot_builder.rs
info: js/babel-plugins/pipeline-operator-fsharp.js
---

# Input

```js
// https://babeljs.io/docs/en/babel-plugin-proposal-pipeline-operator
// https://github.com/valtech-nyc/proposal-fsharp-pipelines

promise
  |> await
  |> x => doubleSay(x, ', ')
  |> capitalize
  |> x => x + '!'
  |> x => new User.Message(x)
  |> x => stream.write(x)
  |> await
  |> console.log;

const result = exclaim(capitalize(doubleSay("hello")));
result //=> "Hello, hello!"

const result = "hello"
  |> doubleSay
  |> capitalize
  |> exclaim;

result //=> "Hello, hello!"

const person = { score: 25 };

const newScore = person.score
  |> double
  |> n => add(7, n)
  |> n => boundScore(0, 100, n);

newScore //=> 57

// As opposed to:
let newScore = boundScore(0, 100, add(7, double(person.score)));

```


# Prettier differences

```diff
--- Prettier
+++ Biome
@@ -3,25 +3,32 @@
 
 promise
   |> await
-  |> (x) => doubleSay(x, ", ")
+  |> x
+=> doubleSay(x, ', ')
   |> capitalize
-  |> (x) => x + "!"
-  |> (x) => new User.Message(x)
-  |> (x) => stream.write(x)
+  |> x => x + '!'
+  |> x => new User.Message(x)
+  |> x => stream.write(x)
   |> await
-  |> console.log;
+  |> console.log
 
 const result = exclaim(capitalize(doubleSay("hello")));
 result; //=> "Hello, hello!"
 
-const result = "hello" |> doubleSay |> capitalize |> exclaim;
+const result = "hello"
+  |> doubleSay
+  |> capitalize
+  |> exclaim;
 
 result; //=> "Hello, hello!"
 
 const person = { score: 25 };
 
-const newScore =
-  person.score |> double |> (n) => add(7, n) |> (n) => boundScore(0, 100, n);
+const newScore = person.score
+  |> double
+  |> n
+=> add(7, n)
+  |> n => boundScore(0, 100, n)
 
 newScore; //=> 57
 
```

# Output

```js
// https://babeljs.io/docs/en/babel-plugin-proposal-pipeline-operator
// https://github.com/valtech-nyc/proposal-fsharp-pipelines

promise
  |> await
  |> x
=> doubleSay(x, ', ')
  |> capitalize
  |> x => x + '!'
  |> x => new User.Message(x)
  |> x => stream.write(x)
  |> await
  |> console.log

const result = exclaim(capitalize(doubleSay("hello")));
result; //=> "Hello, hello!"

const result = "hello"
  |> doubleSay
  |> capitalize
  |> exclaim;

result; //=> "Hello, hello!"

const person = { score: 25 };

const newScore = person.score
  |> double
  |> n
=> add(7, n)
  |> n => boundScore(0, 100, n)

newScore; //=> 57

// As opposed to:
let newScore = boundScore(0, 100, add(7, double(person.score)));
```

# Errors
```
pipeline-operator-fsharp.js:5:4 parse ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  × Expected an expression for the left hand side of the `>` operator.
  
    4 │ promise
  > 5 │   |> await
      │    ^
    6 │   |> x => doubleSay(x, ', ')
    7 │   |> capitalize
  
  i This operator requires a left hand side value
  
pipeline-operator-fsharp.js:6:3 parse ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  × Expected an unary expression but instead found '|'.
  
    4 │ promise
    5 │   |> await
  > 6 │   |> x => doubleSay(x, ', ')
      │   ^
    7 │   |> capitalize
    8 │   |> x => x + '!'
  
  i Expected an unary expression here.
  
    4 │ promise
    5 │   |> await
  > 6 │   |> x => doubleSay(x, ', ')
      │   ^
    7 │   |> capitalize
    8 │   |> x => x + '!'
  
pipeline-operator-fsharp.js:6:4 parse ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  × Expected an expression for the left hand side of the `>` operator.
  
    4 │ promise
    5 │   |> await
  > 6 │   |> x => doubleSay(x, ', ')
      │    ^
    7 │   |> capitalize
    8 │   |> x => x + '!'
  
  i This operator requires a left hand side value
  
pipeline-operator-fsharp.js:6:8 parse ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  × Expected a semicolon or an implicit semicolon after a statement, but found none
  
    4 │ promise
    5 │   |> await
  > 6 │   |> x => doubleSay(x, ', ')
      │        ^^
    7 │   |> capitalize
    8 │   |> x => x + '!'
  
  i An explicit or implicit semicolon is expected here...
  
    4 │ promise
    5 │   |> await
  > 6 │   |> x => doubleSay(x, ', ')
      │        ^^
    7 │   |> capitalize
    8 │   |> x => x + '!'
  
  i ...Which is required to end this statement
  
    2 │ // https://github.com/valtech-nyc/proposal-fsharp-pipelines
    3 │ 
  > 4 │ promise
      │ ^^^^^^^
  > 5 │   |> await
  > 6 │   |> x => doubleSay(x, ', ')
      │   ^^^^^^^
    7 │   |> capitalize
    8 │   |> x => x + '!'
  
pipeline-operator-fsharp.js:18:4 parse ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  × Expected an expression for the left hand side of the `>` operator.
  
    17 │ const result = "hello"
  > 18 │   |> doubleSay
       │    ^
    19 │   |> capitalize
    20 │   |> exclaim;
  
  i This operator requires a left hand side value
  
pipeline-operator-fsharp.js:19:4 parse ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  × Expected an expression for the left hand side of the `>` operator.
  
    17 │ const result = "hello"
    18 │   |> doubleSay
  > 19 │   |> capitalize
       │    ^
    20 │   |> exclaim;
    21 │ 
  
  i This operator requires a left hand side value
  
pipeline-operator-fsharp.js:20:4 parse ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  × Expected an expression for the left hand side of the `>` operator.
  
    18 │   |> doubleSay
    19 │   |> capitalize
  > 20 │   |> exclaim;
       │    ^
    21 │ 
    22 │ result //=> "Hello, hello!"
  
  i This operator requires a left hand side value
  
pipeline-operator-fsharp.js:27:4 parse ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  × Expected an expression for the left hand side of the `>` operator.
  
    26 │ const newScore = person.score
  > 27 │   |> double
       │    ^
    28 │   |> n => add(7, n)
    29 │   |> n => boundScore(0, 100, n);
  
  i This operator requires a left hand side value
  
pipeline-operator-fsharp.js:28:4 parse ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  × Expected an expression for the left hand side of the `>` operator.
  
    26 │ const newScore = person.score
    27 │   |> double
  > 28 │   |> n => add(7, n)
       │    ^
    29 │   |> n => boundScore(0, 100, n);
    30 │ 
  
  i This operator requires a left hand side value
  
pipeline-operator-fsharp.js:28:8 parse ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  × Expected a semicolon or an implicit semicolon after a statement, but found none
  
    26 │ const newScore = person.score
    27 │   |> double
  > 28 │   |> n => add(7, n)
       │        ^^
    29 │   |> n => boundScore(0, 100, n);
    30 │ 
  
  i An explicit or implicit semicolon is expected here...
  
    26 │ const newScore = person.score
    27 │   |> double
  > 28 │   |> n => add(7, n)
       │        ^^
    29 │   |> n => boundScore(0, 100, n);
    30 │ 
  
  i ...Which is required to end this statement
  
    24 │ const person = { score: 25 };
    25 │ 
  > 26 │ const newScore = person.score
       │ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  > 27 │   |> double
  > 28 │   |> n => add(7, n)
       │   ^^^^^
    29 │   |> n => boundScore(0, 100, n);
    30 │ 
  

```