fixes #176

needed to use the DefaultValue attribute on the Zero member of the CEs

Author: TheAngryByrd

src/FsToolkit.ErrorHandling.TaskResult/TaskOptionCE.fs

@@ -514,17 +514,19 @@ type TaskOptionBuilderBase() =
         TaskOptionCode<'TOverall, 'T>(fun sm -> (generator ()).Invoke(&sm))
 
     /// Used to represent no-ops like the implicit empty "else" branch of an "if" expression.
-    // [<DefaultValue>] // TODO: Figureout if this attribute is needed, without it it allows tests to pass with implicit else branches resulting in `Some ()`
-    member inline _.Zero<'TOverall>() : TaskOptionCode<'TOverall, unit> = ResumableCode.Zero()
+    [<DefaultValue>]
+    member inline _.Zero<'TOverall>() : TaskOptionCode<'TOverall, unit> =
+        TaskOptionCode<_, _>
+            (fun sm ->
+                sm.Data.Result <- ValueSome(Some Unchecked.defaultof<'TOverall>)
+                true)
 
     member inline _.Return(value: 'T) : TaskOptionCode<'T, 'T> =
         TaskOptionCode<'T, _>
             (fun sm ->
                 sm.Data.Result <- ValueSome(Some value)
                 true)
 
-
-
     static member inline CombineDynamic
         (
             sm: byref<TaskOptionStateMachine<_>>,

src/FsToolkit.ErrorHandling.TaskResult/TaskResultCE.fs

@@ -544,7 +544,7 @@ type TaskResultBuilderBase() =
         TaskResultCode<'TOverall, 'Error, 'T>(fun sm -> (generator ()).Invoke(&sm))
 
     /// Used to represent no-ops like the implicit empty "else" branch of an "if" expression.
-    // [<DefaultValue>] // TODO: Figureout if this attribute is needed, without it it allows tests to pass with implicit else branches resulting in `Some ()`
+    [<DefaultValue>]
     member inline _.Zero<'TOverall, 'Error>() : TaskResultCode<'TOverall, 'Error, unit> = ResumableCode.Zero()
 
     member inline _.Return(value: 'T) : TaskResultCode<'T, 'Error, 'T> =

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

@@ -234,6 +234,21 @@ let ceTests =
 
                   Expect.equal actual (Some data) "Should be ok"
               }
+          testCaseTask "If do!"
+          <| fun () ->
+              task {
+                  let data = 42
+
+                  let taskRes (call: unit -> Task) maybeCall : Task<Option<int>> =
+                      taskOption {
+                          if true then do! call ()
+
+                          let! (res: string) = maybeCall (): Task<Option<string>>
+                          return data
+                      }
+
+                  ()
+              }
           testCaseTask "Try With"
           <| fun () ->
               task {

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

@@ -278,7 +278,24 @@ let ``TaskResultCE combine/zero/delay/run Tests`` =
                       }
 
                   Expect.equal actual (Result.Ok data) "Should be ok"
-              } ]
+              }
+          testCaseTask "If do!"
+          <| fun () ->
+              task {
+                  let data = 42
+
+                  let taskRes (call: unit -> Task) maybeCall : Task<Result<int, unit>> =
+                      taskResult {
+                          if true then do! call ()
+
+                          let! (res: string) = maybeCall (): Task<Result<string, unit>>
+                          return data
+                      }
+
+                  ()
+              }
+
+          ]