tests

Pentole/result.fs

@@ -1,12 +1,86 @@
-module Pentole.Result
+namespace Pentole
 
-type Result<'o, 'e> with
+module Result =
 
+    let inline protect ([<InlineIfLambda>]f) x =
+        try
+            Ok (f x)
+        with e -> Error e
+
+    let inline pairwise_map fun_ (x: 'a, y: 'a) =
+        match fun_ x with
+        | Error e -> Error e
+        | Ok o ->
+            match fun_ y with | Ok o' -> Ok (o, o') | Error e -> Error e
+
+    let of_option = function | Some s -> Ok s | None -> Error ()
+
+    let zip a b =
+        match (a, b) with
+        | Ok a, Ok b -> Ok (a, b)
+        | Error e, _ -> Error e
+        | _, Error e -> Error e
+
+    module Unsafe =
         /// <summary>
         /// `o` if `Ok o` else throw
         /// </summary>
         /// <param name="result"></param>
-    static member get (result: Result<'o, 'e>) =
-        match result with
+        let inline get r =
+            match r with
             | Ok o -> o
-        | Error e -> failwith $"Can't unwrap Error {e}"
+            | Error e ->
+                $"Tried to access value from Result r, error={e}"
+                |> System.ArgumentException
+                |> raise
+
+/// Module to operate on lists
+module ResultList =
+    /// <summary>
+    /// Transforms a sequence by applying a function that returns a Result, collecting successful results or short-circuiting on the first error.
+    /// </summary>
+    /// 
+    /// <param name="lambda">A function that transforms each element and returns a Result</param>
+    /// <param name="seq_">The input sequence to transform</param>
+    /// <returns>
+    /// <list>
+    /// - Ok of a list containing all successfully transformed elements if all transformations succeed
+    /// </list>
+    /// <list>
+    /// - Error with the first encountered error if any transformation fails
+    /// </list>
+    /// </returns>
+    /// <example>
+    /// Basic usage:
+    ///
+    /// <code>
+    /// let parseInts = ResultList.collect int "123,456,789".Split(',')
+    /// // Returns Ok [123; 456; 789]
+    /// </code>
+    /// 
+    ///
+    /// Error handling:
+    /// <code>
+    /// let parseInts = ResultList.collect (Result.protect int) ["123"; "abc"; "456"]
+    /// // Returns Error (FormatException "The input string 'abc' was not in a correct format.")
+    /// </code>
+    /// 
+    ///
+    /// Custom transformation:
+    ///
+    /// <code>
+    /// let validatePositive x = 
+    ///     if x > 0 then Ok x else Error "Negative value"
+    /// let result = ResultList.collect validatePositive [1; 2; -3; 4]
+    /// // Returns Error "Negative value"
+    /// </code>
+    /// </example>
+    let collect (lambda: 'a -> Result<'ok, 'err>) (seq_: 'a seq) =
+        let rec iter_ acc seq_ =
+            match Seq.tryHead seq_ with
+            | None -> Ok acc
+            | Some x ->
+                match lambda x with
+                | Error e -> Error e
+                | Ok o -> iter_ (o::acc) (Seq.tail seq_)
+        iter_ [] seq_

tests/path_tests.fs

@@ -2,9 +2,9 @@ module Tests.Path
 
 open NUnit.Framework
 
+open Pentole
 open Pentole.TestsExtensions
 open Pentole.Path
-open Pentole.Result
 
 [<Test>]
 let constructor_test () =
@@ -42,8 +42,8 @@ let resolve_test () =
         s
         |> Path.of_string
         |> Result.map FileSystem.resolve
-        |> Result.get
-    let p (n: string ) = Path.of_string n |> Result.get
+        |> Result.Unsafe.get
+    let p (n: string ) = Path.of_string n |> Result.Unsafe.get
 
     "/"            |> test |> Assert.ok_is_equal (p "/")
     "/etc/../"     |> test |> Assert.ok_is_equal (p "/")
@@ -51,7 +51,7 @@ let resolve_test () =
 
 [<Test>]
 let equality_test () =
-    let p (n: string ) = Path.of_string n |> Result.get
+    let p (n: string ) = Path.of_string n |> Result.Unsafe.get
     Assert.are_equal (p "/etc") (p "/etc/")
 (* 
 [<Test>]

tests/result_tests.fs

@@ -0,0 +1,16 @@
+module Tests.Result
+
+open NUnit.Framework
+
+open Pentole.TestsExtensions
+
+open Pentole
+
+[<Test>]
+let err_test () =
+ let got = ResultList.collect (Result.protect int) ["123"; "abc"; "456"]
+ let msg = "The input string 'abc' was not in a correct format."
+
+ match got with
+     | Ok _ -> Assert.Fail "Expected an error"
+     | Error exn -> Assert.are_equal exn.Message msg

tests/tests.fsproj

@@ -10,6 +10,7 @@
 
   <ItemGroup>
     <Compile Include="bytes_tests.fs" />
+    <Compile Include="result_tests.fs" />
     <Compile Include="string_tests.fs" />
     <Compile Include="path_tests.fs" />
     <Compile Include="Program.fs" />