Result Type Module Extensions

Extensions to the Result module which may be useful for processing Result types.

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/// Extends the Result module with additional functions which can be useful for processing Result types.
module Result =
    [<CompiledName("IsOk")>]
    let isOk result = match result with Error _ -> false | Ok _ -> true
  
    [<CompiledName("IsError")>]
    let isError result = match result with Error _ -> true | Ok _ -> false
    
    [<CompiledName("ChooseOk")>]
    let chooseOk result = match result with Error _ -> None | Ok x -> Some x

    [<CompiledName("ChooseError")>]
    let chooseError result = match result with Error err -> Some err | Ok _ -> None

    [<CompiledName("Get")>]
    let getOk result = match result with Error err -> failwithf "Could not get Ok item from Result as it contained an error: %A" err | Ok x -> x

    [<CompiledName("GetError")>]
    let getError result = match result with Error err -> err | Ok x -> failwithf "Could not get Error from Result: %A" x
    
    [<CompiledName("Throw")>]
    let throwOnError result = match result with Error err -> failwith err | Ok _ -> ()

// A common scenario is processing a list of items and handling the results
let mixedBag =
    [|
        Ok 50.0
        Error "Could not retrieve statistics for item: Reason 1"
        Ok 16.5
        Ok 10.1
        Error "Could not retrieve statistics for item: Reason 2"
        Ok 5.0
    |]

// You may want to route the successes to a different workflow
let successes = 
    mixedBag 
    |> Array.choose Result.chooseOk
    
// You may also want to route the failures to a different workflow
let failures =
    mixedBag
    |> Array.choose Result.chooseError
    
printfn "There were %d successes and %d failures for this operation." successes.Length failures.Length

Multiple items
type CompiledNameAttribute =
  inherit Attribute
  new : compiledName:string -> CompiledNameAttribute
  member CompiledName : string

Full name: Microsoft.FSharp.Core.CompiledNameAttribute

--------------------
new : compiledName:string -> CompiledNameAttribute

val isOk : result:'a -> 'b

Full name: Script.Result.isOk

val result : 'a

val isError : result:'a -> 'b

Full name: Script.Result.isError

val chooseOk : result:'a -> 'b

Full name: Script.Result.chooseOk

union case Option.None: Option<'T>

union case Option.Some: Value: 'T -> Option<'T>

val chooseError : result:'a -> 'b

Full name: Script.Result.chooseError

val getOk : result:'a -> 'b

Full name: Script.Result.getOk

val failwithf : format:Printf.StringFormat<'T,'Result> -> 'T

Full name: Microsoft.FSharp.Core.ExtraTopLevelOperators.failwithf

val getError : result:'a -> 'b

Full name: Script.Result.getError

val throwOnError : result:'a -> 'b

Full name: Script.Result.throwOnError

val failwith : message:string -> 'T

Full name: Microsoft.FSharp.Core.Operators.failwith

val mixedBag : obj []

Full name: Script.mixedBag

val successes : obj []

Full name: Script.successes

module Array

from Microsoft.FSharp.Collections

val choose : chooser:('T -> 'U option) -> array:'T [] -> 'U []

Full name: Microsoft.FSharp.Collections.Array.choose

module Result

from Script

Extends the Result module with additional functions which can be useful for processing Result types.

val failures : obj []

Full name: Script.failures

val printfn : format:Printf.TextWriterFormat<'T> -> 'T

Full name: Microsoft.FSharp.Core.ExtraTopLevelOperators.printfn

property System.Array.Length: int

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More information

Link:	http://fssnip.net/7WU
Posted:	5 years ago
Author:	Travis Rosenbaum
Tags:	applicative , extensions , result type