apply

Namespace: FsToolkit.ErrorHandling

Function Signature:

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

Examples

Take the following function for example

// string -> int
let characterCount (s: string) = s.Length

Example 1

let result =
    Ok(Some "foo") // Result<string option, 'error>
    |> ResultOption.apply (Ok(Some characterCount)) // Result<int option, 'error>

// Ok (Some 3)

Example 2

let result =
    Ok None // Result<string option, 'error>
    |> ResultOption.apply (Ok(Some characterCount)) // Result<int option, 'error>

// Ok None

Example 3

let result =
    Error "bad things happened" // Result<string option, string>
    |> ResultOption.apply (Ok(Some characterCount)) // Result<int option, string>

// Error "bad things happened"