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diff --git a/Data/Libraries/Penlight/lua/pl/import_into.lua b/Data/Libraries/Penlight/lua/pl/import_into.lua
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+++ b/Data/Libraries/Penlight/lua/pl/import_into.lua
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+--------------
+-- PL loader, for loading all PL libraries, only on demand.
+-- Whenever a module is implicitly accesssed, the table will have the module automatically injected.
+-- (e.g. `_ENV.tablex`)
+-- then that module is dynamically loaded. The submodules are all brought into
+-- the table that is provided as the argument, or returned in a new table.
+-- If a table is provided, that table's metatable is clobbered, but the values are not.
+-- This module returns a single function, which is passed the environment.
+-- If this is `true`, then return a 'shadow table' as the module
+-- See @{01-introduction.md.To_Inject_or_not_to_Inject_|the Guide}
+
+-- @module pl.import_into
+
+return function(env)
+    local mod
+    if env == true then
+        mod = {}
+        env = {}
+    end
+    local env = env or {}
+
+    local modules = {
+        utils = true,path=true,dir=true,tablex=true,stringio=true,sip=true,
+        input=true,seq=true,lexer=true,stringx=true,
+        config=true,pretty=true,data=true,func=true,text=true,
+        operator=true,lapp=true,array2d=true,
+        comprehension=true,xml=true,types=true,
+        test = true, app = true, file = true, class = true,
+        luabalanced = true, permute = true, template = true,
+        url = true, compat = true,
+        -- classes --
+        List = true, Map = true, Set = true,
+        OrderedMap = true, MultiMap = true, Date = true,
+    }
+    rawset(env,'utils',require 'pl.utils')
+
+    for name,klass in pairs(env.utils.stdmt) do
+        klass.__index = function(t,key)
+            return require ('pl.'..name)[key]
+        end;
+    end
+
+    -- ensure that we play nice with libraries that also attach a metatable
+    -- to the global table; always forward to a custom __index if we don't
+    -- match
+
+    local _hook,_prev_index
+    local gmt = {}
+    local prevenvmt = getmetatable(env)
+    if prevenvmt then
+        _prev_index = prevenvmt.__index
+        if prevenvmt.__newindex then
+            gmt.__index = prevenvmt.__newindex
+        end
+    end
+
+    function gmt.hook(handler)
+        _hook = handler
+    end
+
+    function gmt.__index(t,name)
+        local found = modules[name]
+        -- either true, or the name of the module containing this class.
+        -- either way, we load the required module and make it globally available.
+        if found then
+            -- e..g pretty.dump causes pl.pretty to become available as 'pretty'
+            rawset(env,name,require('pl.'..name))
+            return env[name]
+        else
+            local res
+            if _hook then
+                res = _hook(t,name)
+                if res then return res end
+            end
+            if _prev_index then
+                return _prev_index(t,name)
+            end
+        end
+    end
+
+    if mod then
+        function gmt.__newindex(t,name,value)
+            mod[name] = value
+            rawset(t,name,value)
+        end
+    end
+
+    setmetatable(env,gmt)
+
+    return env,mod or env
+end