map

Namespace: FsToolkit.ErrorHandling
Function Signature:
('a -> 'b) -> Result<'a option, 'c> -> Result<'b option, 'c>
ResultOption.map is the same as Result.map Option.map.
Examples
Take the following functions for example
// string -> int
let remainingCharacters (prompt: string) =
    280 - prompt.Length
Example 1
let result =
    Ok(Some "foo") // Result<string option, 'error>
    |> ResultOption.map remainingCharacters // Result<int option, 'error>
​
// Ok (Some 277)
Example 2
let result =
    Ok None // Result<string option, 'error>
    |> ResultOption.map remainingCharacters // Result<int option, 'error>
​
// Ok None
Example 3
let result =
    Error "bad things happened" // Result<string option, string>
    |> ResultOption.map remainingCharacters // Result<int option, string>
​
// Error "bad things happened"

ignore

map2

Last modified 2mo ago