Factorial

src/Homework1/Factorial.fs

@@ -0,0 +1,20 @@
+namespace Homework1
+
+/// <summary>
+/// Module that implements method that calculates factorial.
+/// </summary>
+module Factorial =
+    /// <summary>
+    /// Calculates factorial.
+    /// </summary>
+    /// <param name="number">Last number in factorial.</param>
+    let factorial number =
+        let rec factorialRec acc n =
+            match n with
+            | 0
+            | 1 -> acc
+            | _ -> factorialRec (acc * n) (n - 1)
+
+        match number with
+        | _ when number < 0 -> None
+        | _ -> Some(factorialRec 1 number)

src/Homework1/Homework1.fsproj

@@ -15,6 +15,7 @@
     </PropertyGroup>
     <ItemGroup>
         <Content Include="paket.references" />
+        <Compile Include="Factorial.fs" />
         <Compile Include="Main.fs" />
     </ItemGroup>
     <Import Project="..\..\.paket\Paket.Restore.targets" />

tests/Homeworks.Tests/Main.fs

@@ -5,5 +5,4 @@ let allTests = testList "all Tests" []
 
 [<EntryPoint>]
 let main argv =
-    allTests
-    |> runTestsWithCLIArgs [] argv
+    allTests |> runTestsWithCLIArgs [] argv