Add Task/AsyncOption defaultValue and defaultWith (#238)

* Add Task/AsyncOption defaultValue and defaultWith

* Add doc comments

Author: sheridanchris

src/FsToolkit.ErrorHandling.TaskResult/TaskOption.fs

@@ -53,3 +53,30 @@ module TaskOption =
             | Some v -> onSome v
             | None -> onNone ()
         )
+
+    /// <summary>
+    ///  Gets the value of the option if the option is <c>Some</c>, otherwise returns the specified default value.
+    /// </summary>
+    /// <param name="value">The specified default value.</param>
+    /// <param name="asyncOption">The input option.</param>
+    /// <returns>
+    /// The option if the option is <c>Some</c>, else the default value.
+    /// </returns>
+    let inline defaultValue (value: 'value) (taskOption: Task<'value option>) =
+        taskOption
+        |> Task.map (Option.defaultValue value)
+
+    /// <summary>
+    ///  Gets the value of the option if the option is <c>Some</c>, otherwise evaluates <paramref name="defThunk"/> and returns the result.
+    /// </summary>
+    /// <param name="defThunk">A thunk that provides a default value when evaluated.</param>
+    /// <param name="asyncOption">The input option.</param>
+    /// <returns>
+    /// The option if the option is <c>Some</c>, else the result of evaluating <paramref name="defThunk"/>.
+    /// </returns>
+    let inline defaultWith
+        ([<InlineIfLambda>] defThunk: unit -> 'value)
+        (taskOption: Task<'value option>)
+        : Task<'value> =
+        taskOption
+        |> Task.map (Option.defaultWith defThunk)

src/FsToolkit.ErrorHandling/AsyncOption.fs

@@ -52,3 +52,30 @@ module AsyncOption =
             | Some v -> onSome v
             | None -> onNone
         )
+
+    /// <summary>
+    ///  Gets the value of the option if the option is <c>Some</c>, otherwise returns the specified default value.
+    /// </summary>
+    /// <param name="value">The specified default value.</param>
+    /// <param name="asyncOption">The input option.</param>
+    /// <returns>
+    /// The option if the option is <c>Some</c>, else the default value.
+    /// </returns>
+    let inline defaultValue (value: 'value) (asyncOption: Async<'value option>) =
+        asyncOption
+        |> Async.map (Option.defaultValue value)
+
+    /// <summary>
+    ///  Gets the value of the option if the option is <c>Some</c>, otherwise evaluates <paramref name="defThunk"/> and returns the result.
+    /// </summary>
+    /// <param name="defThunk">A thunk that provides a default value when evaluated.</param>
+    /// <param name="asyncOption">The input option.</param>
+    /// <returns>
+    /// The option if the option is <c>Some</c>, else the result of evaluating <paramref name="defThunk"/>.
+    /// </returns>
+    let inline defaultWith
+        ([<InlineIfLambda>] defThunk: unit -> 'value)
+        (asyncOption: Async<'value option>)
+        : Async<'value> =
+        asyncOption
+        |> Async.map (Option.defaultWith defThunk)

tests/FsToolkit.ErrorHandling.TaskResult.Tests/TaskOption.fs

@@ -154,6 +154,52 @@ let eitherTests =
             }
     ]
 
+let defaultValueTests =
+    testList "TaskOption.defaultValue Tests" [
+        testCaseTask "Some"
+        <| fun () ->
+            task {
+                let defaultValue = 10
+                let expectedValue = 5
+
+                let taskOption = TaskOption.retn expectedValue
+                let! result = TaskOption.defaultValue defaultValue taskOption
+                Expect.equal result expectedValue ""
+            }
+
+        testCaseTask "None"
+        <| fun () ->
+            task {
+                let expectedValue = 10
+                let taskOption = Task.singleton None
+                let! result = TaskOption.defaultValue expectedValue taskOption
+                Expect.equal result expectedValue ""
+            }
+    ]
+
+let defaultWithTests =
+    testList "TaskOption.defaultWith Tests" [
+        testCaseTask "Some"
+        <| fun () ->
+            task {
+                let defaultValue = 10
+                let expectedValue = 5
+
+                let taskOption = TaskOption.retn expectedValue
+                let! result = TaskOption.defaultWith (fun () -> defaultValue) taskOption
+                Expect.equal result expectedValue ""
+            }
+
+        testCaseTask "None"
+        <| fun () ->
+            task {
+                let expectedValue = 10
+                let taskOption = Task.singleton None
+                let! result = TaskOption.defaultWith (fun () -> expectedValue) taskOption
+                Expect.equal result expectedValue ""
+            }
+    ]
+
 let allTests =
     testList "Task Option Tests" [
         mapTests
@@ -162,4 +208,6 @@ let allTests =
         retnTests
         taskOptionOperatorTests
         eitherTests
+        defaultValueTests
+        defaultWithTests
     ]

tests/FsToolkit.ErrorHandling.Tests/AsyncOption.fs

@@ -127,6 +127,48 @@ let eitherTests =
         }
     ]
 
+let defaultValueTests =
+    testList "TaskOption.defaultValue Tests" [
+        testCaseAsync "Some"
+        <| async {
+            let defaultValue = 10
+            let expectedValue = 5
+
+            let asyncOption = AsyncOption.retn expectedValue
+            let! result = AsyncOption.defaultValue defaultValue asyncOption
+            Expect.equal result expectedValue ""
+        }
+
+        testCaseAsync "None"
+        <| async {
+            let expectedValue = 10
+            let asyncOption = Async.singleton None
+            let! result = AsyncOption.defaultValue expectedValue asyncOption
+            Expect.equal result expectedValue ""
+        }
+    ]
+
+let defaultWithTests =
+    testList "AsyncOption.defaultWith Tests" [
+        testCaseAsync "Some"
+        <| async {
+            let defaultValue = 10
+            let expectedValue = 5
+
+            let asyncOption = AsyncOption.retn expectedValue
+            let! result = AsyncOption.defaultWith (fun () -> defaultValue) asyncOption
+            Expect.equal result expectedValue ""
+        }
+
+        testCaseAsync "None"
+        <| async {
+            let expectedValue = 10
+            let asyncOption = Async.singleton None
+            let! result = AsyncOption.defaultWith (fun () -> expectedValue) asyncOption
+            Expect.equal result expectedValue ""
+        }
+    ]
+
 let allTests =
     testList "Async Option Tests" [
         mapTests
@@ -135,4 +177,6 @@ let allTests =
         retnTests
         asyncOptionOperatorTests
         eitherTests
+        defaultValueTests
+        defaultWithTests
     ]