From c609775d1fc5ae18aadc92b8b65be9c9b1980004 Mon Sep 17 00:00:00 2001
From: William Boman <william@redwill.se>
Date: Tue, 10 Jan 2023 17:53:17 +0100
Subject: feat(functional): add list.index_by (#882)

---
 lua/mason-core/functional/init.lua |  1 +
 lua/mason-core/functional/list.lua | 12 ++++++++++++
 2 files changed, 13 insertions(+)

(limited to 'lua/mason-core/functional')

diff --git a/lua/mason-core/functional/init.lua b/lua/mason-core/functional/init.lua
index 9b52047c..20293bd8 100644
--- a/lua/mason-core/functional/init.lua
+++ b/lua/mason-core/functional/init.lua
@@ -63,6 +63,7 @@ _.drop = list.drop
 _.drop_last = list.drop_last
 _.reduce = list.reduce
 _.split_every = list.split_every
+_.index_by = list.index_by
 
 ---@module "mason-core.functional.relation"
 local relation = lazy_require "mason-core.functional.relation"
diff --git a/lua/mason-core/functional/list.lua b/lua/mason-core/functional/list.lua
index 275bc61a..30e134bd 100644
--- a/lua/mason-core/functional/list.lua
+++ b/lua/mason-core/functional/list.lua
@@ -284,4 +284,16 @@ _.split_every = fun.curryN(function(n, list)
     return res
 end, 2)
 
+---@generic T, U
+---@param index fun(item: T): U
+---@param list T[]
+---@return table<U, T>
+_.index_by = fun.curryN(function(index, list)
+    local res = {}
+    for _, item in ipairs(list) do
+        res[index(item)] = item
+    end
+    return res
+end, 2)
+
 return _
-- 
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