traverseResultA

List.traverseResultA
Namespace: FsToolkit.ErrorHandling
Function Signature:
('a -> Result<'b,'c>) -> 'a list -> Result<'b list, 'c list>
Note that traverse is the same as map >> sequence. See also List.sequenceResultA.
This is applicative, collecting all errors. Compare the example below with traverseResultM.
See also Scott Wlaschin's Understanding traverse and sequence.
Examples
Example 1
// string -> Result<int, string>
let tryParseInt str =
  match Int32.TryParse str with
  | true, x -> Ok x
  | false, _ -> 
    Error (sprintf "unable to parse '%s' to integer" str)
​
["1"; "2"; "3"]
|> List.traverseResultA tryParseInt
// Ok [1; 2; 3]
​
["1"; "foo"; "3"; "bar"]
|> List.traverseResultA tryParseInt
//  Error ["unable to parse 'foo' to integer";
//         "unable to parse 'bar' to integer"]

sequenceResultM

sequenceResultA

Last modified 1yr ago