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Implement TaskValidation module
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‎src/FsToolkit.ErrorHandling/FsToolkit.ErrorHandling.fsproj‎

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<Compile Include="ValidationOp.fs" />
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<Compile Include="ValidationCE.fs" />
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<Compile Include="AsyncValidation.fs" />
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<Compile Include="TaskValidation.fs" />
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<Compile Include="AsyncValidationOp.fs" />
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<Compile Include="AsyncValidationCE.fs" />
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<Compile Include="AsyncOption.fs" />

‎src/FsToolkit.ErrorHandling/TaskValidation.fs‎

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namespace FsToolkit.ErrorHandling
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open System.Threading.Tasks
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/// TaskValidation<'a, 'err> is defined as Task<Result<'a, 'err list>> meaning you can use many of the functions found in the Result and Task module.
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type TaskValidation<'ok, 'error> = Task<Result<'ok, 'error list>>
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[<RequireQualifiedAccess>]
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module TaskValidation =
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let inline ok (value: 'ok) : TaskValidation<'ok, 'error> =
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Ok value
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|> Task.singleton
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let inline error (error: 'error) : TaskValidation<'ok, 'error> =
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Error [ error ]
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|> Task.singleton
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let inline ofResult (result: Result<'ok, 'error>) : TaskValidation<'ok, 'error> =
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Result.mapError List.singleton result
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|> Task.singleton
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let inline ofChoice (choice: Choice<'ok, 'error>) : TaskValidation<'ok, 'error> =
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match choice with
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| Choice1Of2 x -> ok x
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| Choice2Of2 e -> error e
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let inline apply
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(applier: TaskValidation<'okInput -> 'okOutput, 'error>)
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(input: TaskValidation<'okInput, 'error>)
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: TaskValidation<'okOutput, 'error> =
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task {
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let! applier = applier
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let! input = input
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return
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match applier, input with
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| Ok f, Ok x -> Ok(f x)
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| Error errs, Ok _
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| Ok _, Error errs -> Error errs
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| Error errs1, Error errs2 ->
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Error(
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errs1
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@ errs2
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)
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}
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/// <summary>
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/// Returns <c>validation</c> if it is <c>Ok</c>, otherwise returns <c>ifError</c>
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/// </summary>
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/// <param name="ifError">The value to use if <c>validation</c> is <c>Error</c></param>
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/// <param name="validation">The input validation.</param>
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/// <remarks>
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/// </remarks>
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/// <example>
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/// <code>
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/// TaskValidation.error "First" |> TaskValidation.orElse (TaskValidation.error "Second") // evaluates to Error [ "Second" ]
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/// TaskValidation.error "First" |> TaskValidation.orElse (TaskValidation.ok "Second") // evaluates to Ok ("Second")
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/// TaskValidation.ok "First" |> TaskValidation.orElse (TaskValidation.error "Second") // evaluates to Ok ("First")
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/// TaskValidation.ok "First" |> TaskValidation.orElse (TaskValidation.ok "Second") // evaluates to Ok ("First")
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/// </code>
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/// </example>
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/// <returns>
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/// The result if the validation is <c>Ok</c>, else returns <c>ifError</c>.
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/// </returns>
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let inline orElse
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(ifError: TaskValidation<'ok, 'errorOutput>)
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(validation: TaskValidation<'ok, 'errorInput>)
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: TaskValidation<'ok, 'errorOutput> =
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task {
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let! validation = validation
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return!
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validation
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|> Result.either ok (fun _ -> ifError)
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}
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/// <summary>
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/// Returns <c>validation</c> if it is <c>Ok</c>, otherwise executes <c>ifErrorFunc</c> and returns the result.
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/// </summary>
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/// <param name="ifErrorFunc">A function that provides an alternate validation when evaluated.</param>
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/// <param name="validation">The input validation.</param>
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/// <remarks>
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/// <paramref name="ifErrorFunc"/> is not executed unless <c>validation</c> is an <c>Error</c>.
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/// </remarks>
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/// <example>
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/// <code>
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/// TaskValidation.error "First" |> TaskValidation.orElseWith (fun _ -> TaskValidation.error "Second") // evaluates to Error [ "Second" ]
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/// TaskValidation.error "First" |> TaskValidation.orElseWith (fun _ -> TaskValidation.ok "Second") // evaluates to Ok ("Second")
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/// TaskValidation.ok "First" |> TaskValidation.orElseWith (fun _ -> TaskValidation.error "Second") // evaluates to Ok ("First")
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/// TaskValidation.ok "First" |> TaskValidation.orElseWith (fun _ -> TaskValidation.ok "Second") // evaluates to Ok ("First")
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/// </code>
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/// </example>
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/// <returns>
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/// The result if the result is <c>Ok</c>, else the result of executing <paramref name="ifErrorFunc"/>.
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/// </returns>
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let inline orElseWith
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([<InlineIfLambda>] ifErrorFunc: 'errorInput list -> TaskValidation<'ok, 'errorOutput>)
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(validation : TaskValidation<'ok, 'errorInput>)
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: TaskValidation<'ok, 'errorOutput> =
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task {
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let! validation = validation
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return!
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match validation with
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| Ok x -> ok x
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| Error err -> ifErrorFunc err
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}
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/// <summary>
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/// Applies a transformation to the value of a <c>TaskValidation</c> to a new value using the specified mapper function.
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///
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/// Documentation is found here: <href>https://demystifyfp.gitbook.io/fstoolkit-errorhandling/fstoolkit.errorhandling/taskvalidation/map</href>
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/// </summary>
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/// <param name="mapper">The function to apply to the value of the <c>TaskValidation</c> if it is <c>Ok</c>.</param>
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/// <param name="input">The <c>TaskValidation</c> to map.</param>
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/// <returns>A new <c>TaskValidation</c>with the mapped value if the input <c>TaskValidation</c> is <c>Ok</c>, otherwise the original <c>Error</c>.</returns>
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let inline map
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([<InlineIfLambda>] mapper: 'okInput -> 'okOutput)
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(input: TaskValidation<'okInput, 'error>)
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: TaskValidation<'okOutput, 'error> =
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task {
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let! input = input
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return Result.map mapper input
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}
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/// <summary>
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/// Applies a mapper function to two input <c>TaskValidation</c>s, producing a new <c>TaskValidation</c>.
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///
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/// Documentation is found here: <href>https://demystifyfp.gitbook.io/fstoolkit-errorhandling/fstoolkit.errorhandling/taskvalidation/map2</href>
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/// </summary>
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/// <param name="mapper">The function to apply to the inputs.</param>
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/// <param name="input1">The first input <c>TaskValidation</c>.</param>
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/// <param name="input2">The second input <c>TaskValidation</c>.</param>
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/// <returns>A new <c>TaskValidation</c>containing the output of the mapper function if both input <c>TaskValidation</c>s are <c>Ok</c>, otherwise an <c>Error TaskValidation</c>.</returns>
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let inline map2
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([<InlineIfLambda>] mapper: 'okInput1 -> 'okInput2 -> 'okOutput)
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(input1: TaskValidation<'okInput1, 'error>)
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(input2: TaskValidation<'okInput2, 'error>)
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: TaskValidation<'okOutput, 'error> =
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task {
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let! input1 = input1
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let! input2 = input2
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return
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match input1, input2 with
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| Ok x, Ok y -> Ok(mapper x y)
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| Ok _, Error errs -> Error errs
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| Error errs, Ok _ -> Error errs
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| Error errs1, Error errs2 ->
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Error(
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errs1
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@ errs2
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)
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}
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/// <summary>
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/// Applies a mapper function to three input <c>TaskValidation</c>s, producing a new <c>TaskValidation</c>.
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///
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/// Documentation is found here: <href>https://demystifyfp.gitbook.io/fstoolkit-errorhandling/fstoolkit.errorhandling/taskvalidation/map3</href>
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/// </summary>
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/// <param name="mapper">The function to apply to the input <c>TaskValidation</c>s.</param>
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/// <param name="input1">The first input <c>TaskValidation</c>.</param>
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/// <param name="input2">The second input <c>TaskValidation</c>.</param>
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/// <param name="input3">The third input <c>TaskValidation</c>.</param>
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/// <returns>A new <c>TaskValidation</c> with the output of the mapper function applied to the input validations, if all <c>TaskValidation</c>s are <c>Ok</c>, otherwise returns the original <c>Error</c></returns>
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let inline map3
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([<InlineIfLambda>] mapper: 'okInput1 -> 'okInput2 -> 'okInput3 -> 'okOutput)
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(input1: TaskValidation<'okInput1, 'error>)
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(input2: TaskValidation<'okInput2, 'error>)
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(input3: TaskValidation<'okInput3, 'error>)
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: TaskValidation<'okOutput, 'error> =
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task {
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let! input1 = input1
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let! input2 = input2
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let! input3 = input3
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return
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match input1, input2, input3 with
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| Ok x, Ok y, Ok z -> Ok(mapper x y z)
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| Error errs, Ok _, Ok _ -> Error errs
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| Ok _, Error errs, Ok _ -> Error errs
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| Ok _, Ok _, Error errs -> Error errs
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| Error errs1, Error errs2, Ok _ ->
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Error(
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errs1
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@ errs2
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)
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| Ok _, Error errs1, Error errs2 ->
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Error(
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errs1
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@ errs2
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)
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| Error errs1, Ok _, Error errs2 ->
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Error(
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errs1
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@ errs2
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)
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| Error errs1, Error errs2, Error errs3 ->
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Error(
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errs1
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@ errs2
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@ errs3
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)
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}
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/// <summary>
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/// Maps the error value of a <c>TaskValidation</c>to a new error value using the specified error mapper function.
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///
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/// Documentation is found here: <href>https://demystifyfp.gitbook.io/fstoolkit-errorhandling/fstoolkit.errorhandling/taskvalidation/maperror</href>
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/// </summary>
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/// <param name="errorMapper">The function that maps the input error value to the output error value.</param>
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/// <param name="input">The <c>TaskValidation</c>value to map the error value of.</param>
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/// <returns>A new <c>TaskValidation</c>with the same Ok value and the mapped error value.</returns>
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let inline mapError
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([<InlineIfLambda>] errorMapper: 'errorInput -> 'errorOutput)
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(input: TaskValidation<'ok, 'errorInput>)
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: TaskValidation<'ok, 'errorOutput> =
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task {
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let! input = input
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return Result.mapError (List.map errorMapper) input
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}
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/// <summary>
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/// Maps the error values of a <c>TaskValidation</c>to a new error value using the specified error mapper function.
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///
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/// Documentation is found here: <href>https://demystifyfp.gitbook.io/fstoolkit-errorhandling/fstoolkit.errorhandling/taskvalidation/maperror</href>
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/// </summary>
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/// <remarks>
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/// Similar to <c>TaskValidation.mapError</c>, except that the mapping function is passed the full list of errors, rather than each one individually.
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/// </remarks>
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/// <param name="errorMapper">The function that maps the input errors to the output errors.</param>
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/// <param name="input">The <c>TaskValidation</c>value to map the errors of.</param>
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/// <returns>A new <c>TaskValidation</c>with the same Ok value and the mapped errors.</returns>
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let inline mapErrors
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([<InlineIfLambda>] errorMapper: 'errorInput list -> 'errorOutput list)
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(input: TaskValidation<'ok, 'errorInput>)
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: TaskValidation<'ok, 'errorOutput> =
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task {
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let! input = input
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return Result.mapError errorMapper input
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}
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/// <summary>
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/// Takes a transformation function and applies it to the <c>TaskValidation</c> if it is <c>Ok</c>.
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///
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/// Documentation is found here: <href>https://demystifyfp.gitbook.io/fstoolkit-errorhandling/fstoolkit.errorhandling/taskvalidation/bind</href>
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/// </summary>
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/// <param name="binder">The transformation function</param>
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/// <param name="input">The input validation</param>
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/// <typeparam name="'okInput">The type of the successful validation.</typeparam>
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/// <typeparam name="'okOutput">The type of the validation after binding.</typeparam>
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/// <typeparam name="'error">The type of the error.</typeparam>
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/// <returns>Returns a new <c>TaskValidation</c> if the input is <c>Ok</c>, otherwise returns the original <c>TaskValidation</c></returns>
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let inline bind
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([<InlineIfLambda>] binder: 'okInput -> TaskValidation<'okOutput, 'error>)
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(input: TaskValidation<'okInput, 'error>)
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: TaskValidation<'okOutput, 'error> =
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task {
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let! input = input
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match input with
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| Ok x -> return! binder x
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| Error e -> return Error e
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}
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/// <summary>
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/// Takes two <c>TaskValidation</c>s and returns a tuple of the pair or <c>Error</c> if either of them are <c>Error</c>
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///
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/// Documentation is found here: <href>https://demystifyfp.gitbook.io/fstoolkit-errorhandling/fstoolkit.errorhandling/taskvalidation/zip</href>
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/// </summary>
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/// <remarks>
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/// If both validations are <c>Error</c>, the returned <c>Error</c> contains the concatenated lists of errors
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/// </remarks>
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/// <param name="left">The first input validation.</param>
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/// <param name="right">The second input validation.</param>
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/// <returns>A tuple of the pair of the input validation.</returns>
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let inline zip
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(left: TaskValidation<'left, 'error>)
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(right: TaskValidation<'right, 'error>)
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: TaskValidation<'left * 'right, 'error> =
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task {
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let! left = left
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let! right = right
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return
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match left, right with
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| Ok x1res, Ok x2res -> Ok(x1res, x2res)
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| Error e, Ok _ -> Error e
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| Ok _, Error e -> Error e
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| Error e1, Error e2 -> Error(e1 @ e2)
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}

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