From e6dc6097f9314a65c543dfadd3217b0456e315ca Mon Sep 17 00:00:00 2001
From: Matei Adriel <rafaeladriel11@gmail.com>
Date: Sun, 15 Dec 2019 15:20:20 +0200
Subject: [PATCH] fsharp(ygosim): feat: added a helper to create a lens from an
 array index

Signed-off-by: prescientmoon <git@moonythm.dev>
---
 fsharp/ygosim/src/Utils.fs | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/fsharp/ygosim/src/Utils.fs b/fsharp/ygosim/src/Utils.fs
index f241924..dbf2036 100644
--- a/fsharp/ygosim/src/Utils.fs
+++ b/fsharp/ygosim/src/Utils.fs
@@ -1,7 +1,15 @@
 module Utils
 
 module List =
-    let setIndex index value list =
-        List.mapi (fun previous i ->
+    let setIndex index value =
+        List.mapi (fun i previous ->
             if i = index then value
             else previous)
+
+
+    let (.->) = setIndex
+
+module Lens =
+    open FSharpPlus.Lens
+
+    let inline indexToLens index f (array: list<'a>) = f array.[index] <&> fun v -> List.setIndex index v array