WIP src and test cases

Author: Jay Goldstein

src/FsToolkit.ErrorHandling/Option.fs

@@ -321,7 +321,11 @@ module Option =
 
         opt
 
+    /// <summary>
     /// Converts a Option<Async<_>> to an Async<Option<_>>
+    ///
+    /// Documentation is found here: <href>https://demystifyfp.gitbook.io/fstoolkit-errorhandling/fstoolkit.errorhandling/option/sequenceasync</href>
+    /// </summary>
     let inline sequenceAsync (optAsync: Option<Async<'T>>) : Async<Option<'T>> =
         async {
             match optAsync with
@@ -333,6 +337,8 @@ module Option =
 
     /// <summary>
     /// Maps an Async function over an Option, returning an Async Option.
+    ///
+    /// Documentation is found here: <href>https://demystifyfp.gitbook.io/fstoolkit-errorhandling/fstoolkit.errorhandling/option/traverseasync</href>
     /// </summary>
     /// <param name="f">The function to map over the Option.</param>
     /// <param name="opt">The Option to map over.</param>
@@ -343,6 +349,35 @@ module Option =
         : Async<Option<'T>> =
         sequenceAsync ((map f) opt)
 
+    /// <summary>
+    /// Converts a Option<Async<Result<'ok,'error>>> to an Async<Result<Option<'ok>,'error>>
+    /// </summary>
+    let inline sequenceAsyncResult
+        (optAsyncResult: Option<Async<Result<'T, 'E>>>)
+        : Async<Result<Option<'T>, 'E>> =
+        async {
+            match optAsyncResult with
+            | Some asncRes ->
+                let! xRes = asncRes
+
+                return
+                    xRes
+                    |> Result.map Some
+            | None -> return Ok None
+        }
+
+    /// <summary>
+    /// Maps an AsyncResult function over an Option, returning an AsyncResult Option.
+    /// </summary>
+    /// <param name="f">The function to map over the Option.</param>
+    /// <param name="opt">The Option to map over.</param>
+    /// <returns>An AsyncResult Option with the mapped value.</returns>
+    let inline traverseAsyncResult
+        ([<InlineIfLambda>] f: 'T -> Async<Result<'U, 'E>>)
+        (opt: Option<'T>)
+        : Async<Result<Option<'U>, 'E>> =
+        sequenceAsyncResult ((map f) opt)
+
     /// <summary>
     /// Creates an option from a boolean value and a value of type 'a.
     /// If the boolean value is true, returns <c>Some</c> value.

tests/FsToolkit.ErrorHandling.Tests/Option.fs

@@ -211,6 +211,52 @@ let sequenceAsyncTests =
         }
     ]
 
+let sequenceAsyncResultTests =
+    ftestList "Option.sequenceAsyncResult Tests" [
+        testCaseAsync "sequenceAsyncResult returns the async Ok value if Some"
+        <| async {
+            let optAsyncOk =
+                async { return Ok "foo" }
+                |> Some
+
+            let! valueRes =
+                optAsyncOk
+                |> Option.sequenceAsyncResult
+
+            let value = Expect.wantOk valueRes "Expect to get back OK"
+            Expect.equal value (Some "foo") "Expect to get back value"
+        }
+
+        testCaseAsync "sequenceAsyncResult returns the async Error value if Some"
+        <| async {
+            let optAsyncOk =
+                async { return Error "error" }
+                |> Some
+
+            let! valueRes =
+                optAsyncOk
+                |> Option.sequenceAsyncResult
+
+            let errorValue = Expect.wantError valueRes "Expect to get back Error"
+            Expect.equal errorValue "error" "Expect to get back the error value"
+        }
+
+        testCaseAsync "sequenceAsyncResult returns None if None"
+        <| async {
+            let optAsyncNone = None
+
+            let! valueRes =
+                optAsyncNone
+                |> Option.sequenceAsyncResult
+
+            let valueNone = Expect.wantOk valueRes "Expect to get back OK"
+            Expect.isNone valueNone "Expect to get back None"
+
+            // check things actually fail when fail
+            Expect.isSome valueNone "This should fail"
+        }
+    ]
+
 let traverseAsyncTests =
     testList "Option.traverseAsync Tests" [
         testCaseAsync "traverseAsync returns the async value if Some"
@@ -259,6 +305,23 @@ let traverseResultTests =
             |> Expect.hasOkValue (Some validLng)
     ]
 
+// to do
+// let traverseAsyncResultTests =
+//     testList "Option.traverseAsyncResult Tests" [
+//         testCaseAsync "traverseAsyncResult with valid latitute data"
+//         <| async {
+//             let tryCreateLatAsync = fun l -> async { return Latitude.TryCreate l }
+//
+//             let! valueRes =
+//                 Some lat
+//                 |> Option.traverseAsyncResult tryCreateLatAsync
+//
+//             let value = Expect.wantOk valueRes "Expect to get OK"
+//             Expect.equal value (Some validLat) "Expect to get valid latitute"
+//
+//         }
+//
+//     ]
 
 let tryParseTests =
     testList "Option.tryParse" [