traverseOptionM

Namespace: FsToolkit.ErrorHandling

Applies the given function to each element in the input list, and returns an option containing a list of the results. If any of the function applications return None, the entire result will be None.

Function Signature

('a -> 'b option) -> 'a list -> 'b list option

Examples

Example 1

let tryParseInt (s: string) =
    match Int32.TryParse(s) with
    | true, i -> Some i
    | false, _ -> None

let myList = ["123"; "456"; "789"]
  
List.traverseOptionM tryParseInt myList
// Some [123; 456; 789]

Example 2

let tryParseInt (s: string) =
    match Int32.TryParse(s) with
    | true, i -> Some i
    | false, _ -> None

let myList = ["123"; "Not a number"; "789"]

List.traverseOptionM tryParseInt myList
// None