// string -> int
let getErrorCode (messages: string list) =
match messages |> List.tryFind ((=) "bad things happened") with
| Some _ -> [1]
| _ -> [0]
Example 1
let result =
TaskValidation.ok "all good" // TaskValidation<string, string>
|> TaskValidation.mapErrors getErrorCode // TaskValidation<string, int>
// task { Ok "all good" }
Example 2
let result : TaskValidation<string, int> =
TaskValidation.error "bad things happened" // TaskValidation<string, string>
|> TaskValidation.mapErrors getErrorCode // TaskValidation<string, int>
// task { Error [1] }