map2

AsyncResultOption.map2

Namespace: FsToolkit.ErrorHandling

Function Signature:

('a -> 'b -> 'c)
  -> Async<Result<'a option, 'd>>
  -> Async<Result<'b option, 'd>>
  -> Async<Result<'c option, 'd>>

Examples

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

Example 1

Given the following functions:

getPostById : PostId -> Async<Result<Post option, exn>>
getUserById : UserId -> Async<Result<User option, exn>>
userTweet : Post -> User -> UserTweet

Then given a PostId and a UserId, we can call userTweet like this:

// Async<Result<UserTweet option, Exception>>
AsyncResultOption.map2 userTweet (getPostById postId) (getUserById userId)