map2

TaskResult.map2

Namespace: FsToolkit.ErrorHandling
Function Signature:
('a -> 'b -> 'c) -> Task<Result<'a, 'd>> -> Task<Result<'b, 'd>>
-> Task<Result<'c, 'd>>

Examples

Note: Many use-cases requiring map operations can also be solved using the taskResult computation expression.

Example 1

Given the functions
getFollowerIds : UserId -> Task<Result<UserId, exn>>
createPost : CreatePostRequest -> Task<Result<PostId, exn>>
And the type
type NotifyNewPostRequest =
{ UserIds : UserId list
NewPostId : PostId }
static member Create userIds newPostsId =
{UserIds = userIds; NewPostId = newPostsId}
We can create a NotifyNewPostRequest using TaskResult.map2 as below:
let createPostAndGetNotifyRequest (req : CreatePostRequest) =
// Task<Result<UserId, exn>>
let getFollowersResult = getFollowerIds req.UserId
// Task<Result<PostId, exn>>
let createPostResult = createPost req
// Task<Result<NotifyNewPostRequest, exn>>
let newPostRequestResult =
TaskResult.map2
NotifyNewPostRequest.Create getFollowersResult createPostResult
// ...
Last modified 1yr ago