sequenceResultA

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sequenceResultA

List.sequenceResultA
Namespace: FsToolkit.ErrorHandling
Function Signature:
Result<'a, 'b> list -> Result<'a list, 'b list>
Note that sequence is the same as traverse id. See also List.traverseResultA.
This is applicative, collecting all errors. Compare the example below with sequenceResultM.
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.map tryParseInt
|> List.sequenceResultA
// Ok [1; 2; 3]
​
["1"; "foo"; "3"; "bar"]
|> List.map tryParseInt
|> List.sequenceResultA
// Error ["unable to parse 'foo' to integer"; 
//        "unable to parse 'bar' to integer"]

traverseResultA

traverseAsyncResultM

Last modified 9mo ago

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Outline

List.sequenceResultA

Examples