orElse.md

TaskValidation.orElse / TaskValidation.orElseWith

Namespace: FsToolkit.ErrorHandling

orElse

orElse returns the original TaskValidation if it is Ok, otherwise returns the provided alternative TaskValidation.

Function Signature

TaskValidation<'ok, 'errorOutput> -> TaskValidation<'ok, 'errorInput> -> TaskValidation<'ok, 'errorOutput>

Examples

Example 1

let result =
    TaskValidation.ok "First"
    |> TaskValidation.orElse (TaskValidation.ok "Second")

// task { Ok "First" }

Example 2

let result =
    TaskValidation.error "First"
    |> TaskValidation.orElse (TaskValidation.ok "Second")

// task { Ok "Second" }

Example 3

let result =
    TaskValidation.error "First"
    |> TaskValidation.orElse (TaskValidation.error "Second")

// task { Error ["Second"] }

---

orElseWith

orElseWith returns the original TaskValidation if it is Ok, otherwise calls the given function with the error list and returns its result.

Function Signature

('errorInput list -> TaskValidation<'ok, 'errorOutput>) -> TaskValidation<'ok, 'errorInput> -> TaskValidation<'ok, 'errorOutput>

Examples

Example 1

let result =
    TaskValidation.ok "First"
    |> TaskValidation.orElseWith (fun _ -> TaskValidation.ok "Second")

// task { Ok "First" }

Example 2

let result =
    TaskValidation.error "First"
    |> TaskValidation.orElseWith (fun _ -> TaskValidation.ok "Second")

// task { Ok "Second" }

Example 3

let result =
    TaskValidation.error "First"
    |> TaskValidation.orElseWith (fun errors ->
        TaskValidation.error $"Recovered from: %A{errors}")

// task { Error ["Recovered from: [\"First\"]"] }