Add formatting guidance for lazy expressions in F#

Co-authored-by: BillWagner <[email protected]>

Author: Copilot

docs/fsharp/language-reference/lazy-expressions.md

@@ -1,7 +1,7 @@
 ---
 title: Lazy Expressions
 description: Learn how F# lazy expressions can improve the performance of your apps and libraries.
-ms.date: 08/15/2020
+ms.date: 10/02/2025
 ---
 # Lazy Expressions
 
@@ -27,6 +27,21 @@ The following code illustrates the use of lazy expressions and the use of `Force
 
 Lazy evaluation, but not the `Lazy` type, is also used for sequences. For more information, see [Sequences](sequences.md).
 
+## Formatting
+
+For multiline lazy expressions, place the opening parenthesis on the same line as the `lazy` keyword, with the expression body indented one level:
+
+```fsharp
+let expensiveCalculation =
+    lazy (
+        let step1 = performStep1()
+        let step2 = performStep2 step1
+        step2 * 2
+    )
+```
+
+For more information on formatting lazy expressions, see the [F# formatting guide](../style-guide/formatting.md#formatting-lazy-expressions).
+
 ## See also
 
 - [F# Language Reference](index.md)

docs/fsharp/style-guide/formatting.md

@@ -1,7 +1,7 @@
 ---
 title: F# code formatting guidelines
 description: Learn guidelines for formatting F# code.
-ms.date: 11/01/2023
+ms.date: 10/02/2025
 ---
 # F# code formatting guidelines
 
@@ -539,6 +539,41 @@ let useAddEntry () =
         bar ()
 ```
 
+### Formatting lazy expressions
+
+When writing single-line lazy expressions, keep everything on one line:
+
+```fsharp
+// ✔️ OK
+let x = lazy (computeValue())
+
+// ✔️ OK  
+let y = lazy (a + b)
+```
+
+For multiline lazy expressions, place the opening parenthesis on the same line as the `lazy` keyword, with the expression body indented one level and the closing parenthesis aligned with the opening:
+
+```fsharp
+// ✔️ OK
+let v =
+    lazy (
+        // some code
+        let x = computeExpensiveValue()
+        let y = computeAnotherValue()
+        x + y
+    )
+
+// ✔️ OK
+let handler =
+    lazy (
+        let connection = openConnection()
+        let data = fetchData connection
+        processData data
+    )
+```
+
+This follows the same pattern as other function applications with multiline arguments. The opening parenthesis stays with `lazy`, and the expression is indented one level.
+
 ### Formatting arithmetic and binary expressions
 
 Always use white space around binary arithmetic expressions: