Merge pull request #1004 from Happypig375/patch-5

Update Sequence Expressions snippet to use implicit yields

Author: dsyme

_snippets/computation_expressions.md

@@ -5,13 +5,12 @@ excerpt_separator: <!--more-->
 code: |
     // Define a custom computation expression for validation
     type ValidationBuilder() =
-        member _.Bind(x, f) = 
+        member _.Bind(x, f) = // Defines "let!"
             match x with
             | Ok value -> f value
             | Error e -> Error e
-        member _.Return(x) = Ok x
-        member _.ReturnFrom(x) = x
-
+        member _.Return(x) = Ok x // Defines "return"
+        member _.ReturnFrom(x) = x // Defines "return!"
     let validate = ValidationBuilder()
 
     type Person = { Name: string; Age: int }
@@ -22,11 +21,14 @@ code: |
             if age >= 0 && age < 150 then Ok age
             else Error "Age must be between 0 and 150"
             
-        let! validName = 
+        let! nonEmptyName = 
             if String.length name > 0 then Ok name
             else Error "Name cannot be empty"
             
-        return { Name = validName; Age = validAge }
+        if String.length name > 100 then
+            return! Error "Name is too long!"
+        else
+            return { Name = nonEmptyName; Age = validAge }
     }
 ---
 ## Clean Code with Computation Expressions

_snippets/sequence_expressions.md

@@ -3,15 +3,14 @@ order: 15
 title: SequenceExpressions.fs
 excerpt_separator: <!--more-->
 code: |
-    // A function generating a sequence of numbers
     let rec fizzBuzzSeq n = seq {
-        yield
-            match n with
-            | x when x % 15 = 0 -> "fizzbuzz"
-            | x when x % 3 = 0 -> "fizz"
-            | x when x % 5 = 0 -> "buzz"
-            | _ -> n.ToString()
-
+        match n with
+        | x when x % 15 = 0 -> "fizzbuzz"
+        | x when x % 3 = 0 -> "fizz"
+        | x when x % 5 = 0 -> "buzz"
+        | _ -> n.ToString()
+        
+        // Tail recursion makes this as efficient as a "while" loop
         yield! fizzBuzzSeq (n + 1)
     }