diff --git a/_G.yml b/_G.yml
new file mode 100644
index 0000000..52da894
--- /dev/null
+++ b/_G.yml
@@ -0,0 +1,246 @@
+__root: &__root_t0x4004f960
+ _G: *__root_t0x4004f960
+ _VERSION: Lua 5.1
+ arg: &arg_t0x40055cc8
+  "-1": luajit
+  0: run.lua
+ assert: fbuiltin#2
+ bit: &bit_t0x40054d58
+  arshift: fbuiltin#70
+  band: fbuiltin#73
+  bnot: fbuiltin#66
+  bor: fbuiltin#74
+  bswap: fbuiltin#67
+  bxor: fbuiltin#75
+  lshift: fbuiltin#68
+  rol: fbuiltin#71
+  ror: fbuiltin#72
+  rshift: fbuiltin#69
+  tobit: fbuiltin#65
+  tohex: fbuiltin#76
+ collectgarbage: fbuiltin#27
+ coroutine: &coroutine_t0x40051730
+  create: fbuiltin#32
+  resume: fbuiltin#34
+  running: fbuiltin#31
+  status: fbuiltin#30
+  wrap: fbuiltin#36
+  yield: fbuiltin#33
+ debug: &debug_t0x40054740
+  debug: fbuiltin#145
+  getfenv: fbuiltin#134
+  gethook: fbuiltin#144
+  getinfo: fbuiltin#136
+  getlocal: fbuiltin#137
+  getmetatable: fbuiltin#132
+  getregistry: fbuiltin#131
+  getupvalue: fbuiltin#139
+  setfenv: fbuiltin#135
+  sethook: fbuiltin#143
+  setlocal: fbuiltin#138
+  setmetatable: fbuiltin#133
+  setupvalue: fbuiltin#140
+  traceback: fbuiltin#146
+  upvalueid: fbuiltin#141
+  upvaluejoin: fbuiltin#142
+ dofile: fbuiltin#25
+ dump: f0x4005dd40
+ error: fbuiltin#19
+ gcinfo: fbuiltin#26
+ getfenv: fbuiltin#10
+ getmetatable: fbuiltin#8
+ io: &io_t0x40052a90
+  close: fbuiltin#112
+  flush: fbuiltin#115
+  input: fbuiltin#116
+  lines: fbuiltin#118
+  open: fbuiltin#109
+  output: fbuiltin#117
+  popen: fbuiltin#110
+  read: fbuiltin#113
+  stderr: file (0x7ff9dd21f500)
+  stdin: file (0x7ff9dd21e8a0)
+  stdout: file (0x7ff9dd21f5e0)
+  tmpfile: fbuiltin#111
+  type: fbuiltin#119
+  write: fbuiltin#114
+ ipairs: fbuiltin#7
+ jit: &jit_t0x40055318
+  arch: x64
+  attach: fbuiltin#151
+  flush: fbuiltin#149
+  off: fbuiltin#148
+  on: fbuiltin#147
+  opt: &opt_t0x40055bd8
+   start: fbuiltin#163
+  os: Linux
+  status: fbuiltin#150
+  util: &util_t0x400556a0
+   funcbc: fbuiltin#153
+   funcinfo: fbuiltin#152
+   funck: fbuiltin#154
+   funcuvname: fbuiltin#155
+   ircalladdr: fbuiltin#162
+   traceexitstub: fbuiltin#161
+   traceinfo: fbuiltin#156
+   traceir: fbuiltin#157
+   tracek: fbuiltin#158
+   tracemc: fbuiltin#160
+   tracesnap: fbuiltin#159
+  version: LuaJIT 2.0.4
+  version_num: 20004
+ load: fbuiltin#23
+ loadfile: fbuiltin#22
+ loadstring: fbuiltin#24
+ math: &math_t0x40053b60
+  abs: fbuiltin#37
+  acos: fbuiltin#47
+  asin: fbuiltin#46
+  atan: fbuiltin#48
+  atan2: fbuiltin#57
+  ceil: fbuiltin#39
+  cos: fbuiltin#44
+  cosh: fbuiltin#50
+  deg: fbuiltin#54
+  exp: fbuiltin#42
+  floor: fbuiltin#38
+  fmod: fbuiltin#59
+  frexp: fbuiltin#52
+  huge: inf
+  ldexp: fbuiltin#60
+  log: fbuiltin#56
+  log10: fbuiltin#41
+  max: fbuiltin#62
+  min: fbuiltin#61
+  mod: fbuiltin#59
+  modf: fbuiltin#53
+  pi: 3.1415926535898
+  pow: fbuiltin#58
+  rad: fbuiltin#55
+  random: fbuiltin#63
+  randomseed: fbuiltin#64
+  sin: fbuiltin#43
+  sinh: fbuiltin#49
+  sqrt: fbuiltin#40
+  tan: fbuiltin#45
+  tanh: fbuiltin#51
+ module: f0x40051ee0
+ newproxy: fbuiltin#28
+ next: fbuiltin#4
+ os: &os_t0x40052fd0
+  clock: fbuiltin#126
+  date: fbuiltin#127
+  difftime: fbuiltin#129
+  execute: fbuiltin#120
+  exit: fbuiltin#125
+  getenv: fbuiltin#124
+  remove: fbuiltin#121
+  rename: fbuiltin#122
+  setlocale: fbuiltin#130
+  time: fbuiltin#128
+  tmpname: fbuiltin#123
+ package: &package_t0x40051ac8
+  config: 
+   /
+   ;
+   ?
+   !
+   -
+  cpath: /home/notwa/opt/local/lib/?.so;/home/notwa/.luarocks/lib/lua/5.1/?.so;/home/notwa/opt/local/lib/lua/5.1/?.so;./?.so;/usr/local/lib/lua/5.1/?.so;/usr/local/lib/lua/5.1/loadall.so
+  loaded: &loaded_t0x40050b38
+   _G: *__root_t0x4004f960
+   bit: *bit_t0x40054d58
+   coroutine: *coroutine_t0x40051730
+   debug: *debug_t0x40054740
+   extra: &extra_t0x4005cd30
+    add_zeros: f0x4005db58
+    mixed_sorter: f0x4005db98
+    opairs: f0x4005cca8
+    order_keys: f0x4005b2f8
+    strpad: f0x4004f8b8
+    traverse: f0x4005cce8
+   io: *io_t0x40052a90
+   jit: *jit_t0x40055318
+   "jit.opt": *opt_t0x40055bd8
+   "jit.util": *util_t0x400556a0
+   math: *math_t0x40053b60
+   os: *os_t0x40052fd0
+   package: *package_t0x40051ac8
+   pt: &pt_t0x4005ce20
+    __metatable: *pt_t0x4005ce20
+    __call: f0x4005dc98
+    __index: *pt_t0x4005ce20
+    inner: f0x4005dde0
+    outer: f0x4005dd18
+    outer_old: f0x4005dc00
+    safecanon: f0x4005dd60
+    safekey: f0x4005dd80
+    safeval: f0x4005ddc0
+    write: f0x4005dcd8
+   string: *string_t0x400534b0
+   table: *table_t0x400522f8
+  loaders: &loaders_t0x40051c38
+   1: f0x40051c88
+   2: f0x40051cb0
+   3: f0x40051cd8
+   4: f0x40051d00
+  loadlib: f0x40051b58
+  path: /home/notwa/.luarocks/share/lua/5.1/?.lua;/home/notwa/.luarocks/share/lua/5.1/?/init.lua;/home/notwa/opt/local/share/lua/5.1/?.lua;/home/notwa/opt/local/share/lua/5.1/?/init.lua;./?.lua;/home/notwa/opt/local/share/luajit-2.1.0-beta1/?.lua;/usr/local/share/lua/5.1/?.lua;/usr/local/share/lua/5.1/?/init.lua
+  preload: &preload_t0x400520c0
+   ffi: f0x40055c80
+  searchpath: f0x40051ba0
+  seeall: f0x40051bf0
+ pairs: fbuiltin#5
+ pcall: fbuiltin#20
+ print: fbuiltin#29
+ rawequal: fbuiltin#14
+ rawget: fbuiltin#12
+ rawset: fbuiltin#13
+ require: f0x40051f28
+ select: fbuiltin#16
+ setfenv: fbuiltin#11
+ setmetatable: fbuiltin#9
+ string: &string_t0x400534b0
+  byte: fbuiltin#78
+  char: fbuiltin#79
+  dump: fbuiltin#85
+  find: fbuiltin#86
+  format: fbuiltin#91
+  gfind: fbuiltin#89
+  gmatch: fbuiltin#89
+  gsub: fbuiltin#90
+  len: fbuiltin#77
+  lower: fbuiltin#83
+  match: fbuiltin#87
+  rep: fbuiltin#81
+  reverse: fbuiltin#82
+  sub: fbuiltin#80
+  upper: fbuiltin#84
+ t: &t_t0x4005e298
+  A: hello
+  B: &B_t0x4005e328
+   a: beep
+   b: boop
+   c: burp
+   d: *d_t0x4005e550
+  C: &d_t0x4005e550
+   a: nude
+   b: dude
+   c: lewd
+   d: *B_t0x4005e328
+  D: goodbye
+  E: *t_t0x4005e298
+ table: &table_t0x400522f8
+  concat: fbuiltin#98
+  foreach: fbuiltin#93
+  foreachi: fbuiltin#92
+  getn: fbuiltin#94
+  insert: fbuiltin#96
+  maxn: fbuiltin#95
+  remove: fbuiltin#97
+  sort: fbuiltin#99
+ tonumber: fbuiltin#17
+ tostring: fbuiltin#18
+ type: fbuiltin#3
+ unpack: fbuiltin#15
+ xpcall: fbuiltin#21
diff --git a/extra.lua b/extra.lua
new file mode 100755
index 0000000..fb5982b
--- /dev/null
+++ b/extra.lua
@@ -0,0 +1,69 @@
+local insert = table.insert
+local pairs = pairs
+local rawget = rawget
+local sort = table.sort
+local tostring = tostring
+local type = type
+
+local function strpad(num, count, pad)
+    num = tostring(num)
+    return (pad:rep(count)..num):sub(#num)
+end
+
+local function add_zeros(num, count)
+    return strpad(num, count - 1, '0')
+end
+
+local function mixed_sorter(a, b)
+    a = type(a) == 'number' and add_zeros(a, 16) or tostring(a)
+    b = type(b) == 'number' and add_zeros(b, 16) or tostring(b)
+    return a < b
+end
+
+-- loosely based on http://lua-users.org/wiki/SortedIteration
+-- the original didn't make use of closures for who knows why
+local function order_keys(t)
+    local oi = {}
+    for key in pairs(t) do
+        insert(oi, key)
+    end
+    sort(oi, mixed_sorter)
+    return oi
+end
+
+local function opairs(t, cache)
+    local oi = cache and cache[t] or order_keys(t)
+    if cache then
+        cache[t] = oi
+    end
+    local i = 0
+    return function()
+        i = i + 1
+        local key = oi[i]
+        if key ~= nil then return key, t[key] end
+    end
+end
+
+local function traverse(path)
+    if not path then return end
+    local parent = _G
+    local key
+    for w in path:gfind("[%w_]+") do
+        if key then
+            parent = rawget(parent, key)
+            if type(parent) ~= 'table' then return end
+        end
+        key = w
+    end
+    if not key then return end
+    return {parent=parent, key=key}
+end
+
+return {
+    strpad = strpad,
+    add_zeros = add_zeros,
+    mixed_sorter = mixed_sorter,
+    order_keys = order_keys,
+    opairs = opairs,
+    traverse = traverse,
+}
diff --git a/init.lua b/init.lua
new file mode 100644
index 0000000..e60915d
--- /dev/null
+++ b/init.lua
@@ -0,0 +1,2 @@
+local path = string.gsub(..., "[^.]+$", "")
+return require(path.."pt")
diff --git a/pt.lua b/pt.lua
new file mode 100755
index 0000000..821634f
--- /dev/null
+++ b/pt.lua
@@ -0,0 +1,203 @@
+local path = string.gsub(..., "[^.]+$", "")
+local extra = require(path.."extra")
+local opairs = extra.opairs
+
+local pt = {}
+pt.__index = pt
+setmetatable(pt, pt)
+
+local function rawstr(v)
+    if v == nil then return 'nil' end
+    local mt = getmetatable(v)
+    local ts = mt and rawget(mt, '__tostring')
+    if not ts then return tostring(v) end
+    mt.__tostring = nil
+    local s = tostring(v)
+    mt.__tostring = ts
+    return s
+end
+
+local function getaddr(t)
+    return rawstr(t):sub(#type(t) + 3)
+end
+
+local function copy(t)
+    -- shallow copy
+    if type(t) ~= 'table' then return end
+    local new = {}
+    for k,v in pairs(t) do
+        new[k] = v
+    end
+    return new
+end
+
+function pt.__call(pt, args)
+    -- print a table as semi-valid YAML
+    -- with references to prevent recursion/duplication
+    local t = args.table or args[1]
+    local self = {}
+    setmetatable(self, pt)
+    self.seen = copy(args.seen) or {}
+    self.skipped = copy(args.skipped) or {}
+    self.seen_elsewhere = args.seen or {}
+    self.depth = args.depth or 16
+    self.writer = args.writer or io.write
+    self.skeleton = args.skeleton or false
+    self.outer = args.alt_order and self.outer_old or self.outer
+    self.noncanon = args.noncanon or false
+    self.indent = args.indent or ' '
+    self.queued = {}
+    self.cache = {}
+    self.canonicalized = {}
+    self:inner('__root', t, '')
+    return self.seen
+end
+
+function pt:write(...)
+    self.writer(...)
+end
+
+function pt:safecanon(k)
+    local s = tostring(k)
+    return s:gsub('[^%w_]', '_')
+end
+
+function pt:safekey(k)
+    if type(k) == 'table' then
+        return 't'..getaddr(k)
+    end
+    local s = tostring(k)
+    s = s:gsub('[\r\n]', '')
+    return s:find('[^%w_]') and ('%q'):format(s) or s
+end
+
+function pt:safeval(v, indentation)
+    if type(v) == 'function' then
+        return 'f'..getaddr(v)
+    end
+    local s = tostring(v)
+    if type(v) == 'number' then
+        return s
+    end
+    -- TODO: move newline/indentation handling to another function?
+    if s:find('[\r\n]') then
+        s = ('\n'..s):gsub('[\r\n]', '\n'..indentation..self.indent)
+    end
+    --local safe = ('%q'):format(s)
+    --return s == safe:sub(2, -2) and s or safe
+    -- TODO: finish matching valid characters
+    return s:find('[^%w_()[]{}.]') and ('%q'):format(s) or s
+end
+
+function pt:inner(k, v, indentation)
+    if type(v) ~= 'table' then
+        if self.skeleton then return end
+        self:write(indentation, self:safekey(k), ': ')
+        self:write(self:safeval(v, indentation), '\n')
+        return
+    end
+
+    local addr = getaddr(v)
+    self:write(indentation, self:safekey(k))
+
+    local canon
+    if not self.noncanon and type(k) ~= 'table' then
+        canon = self.canonicalized[addr]
+        if canon == nil then
+            canon = self:safecanon(k)..'_t'..addr
+            self.canonicalized[addr] = canon
+        end
+    else
+        canon = 't'..addr
+    end
+
+    if #indentation > self.depth or self.skipped[addr] then
+        --self.skipped[addr] = true -- TODO: extra logics
+        self:write(': #', canon, '\n')
+        return
+    end
+
+    if self.seen[addr] or self.queued[addr] then
+        self:write(': *', canon, self.seen_elsewhere[addr] and ' #\n' or '\n')
+        return
+    end
+
+    self.seen[addr] = true
+
+    self:write(': &', canon, '\n')
+    self:outer(v, indentation..self.indent)
+end
+
+function pt:outer_old(t, indentation)
+    if type(t) ~= "table" then
+        local s = self:safeval(t, indentation)
+        self:write(indentation, s, '\n')
+        return
+    end
+
+    local ours = {}
+    local not_ours = {}
+
+    for k,v in opairs(t) do
+        if type(v) == 'table' then
+            local addr = getaddr(v)
+            if not (self.queued[addr] or self.seen[addr] or self.skipped[addr]) then
+                self.queued[addr] = true
+                ours[k] = v
+            else
+                not_ours[k] = v
+            end
+        else
+            self:inner(k, v, indentation)
+        end
+    end
+
+    for k,v in opairs(not_ours) do
+        self:inner(k, v, indentation)
+    end
+
+    for k,v in opairs(ours) do
+        self.queued[getaddr(v)] = nil
+        self:inner(k, v, indentation)
+    end
+
+    local mt = getmetatable(t)
+    if mt ~= nil then
+        self:inner('__metatable', mt, indentation)
+    end
+end
+
+function pt:outer(t, indentation)
+    if type(t) ~= "table" then
+        local s = self:safeval(t, indentation)
+        self:write(indentation, s, '\n')
+        return
+    end
+
+    local ours = {}
+
+    for k,v in opairs(t, self.cache) do
+        if type(v) == 'table' then
+            local addr = getaddr(v)
+            if not (self.queued[addr] or self.seen[addr] or self.skipped[addr]) then
+                self.queued[addr] = true
+                ours[k] = addr
+            end
+        end
+    end
+
+    local mt = getmetatable(t)
+    if mt ~= nil then
+        self:inner('__metatable', mt, indentation)
+    end
+
+    for k,v in opairs(t, self.cache) do
+        local addr = ours[k]
+        if addr then
+            self.queued[addr] = nil
+        end
+        self:inner(k, v, indentation)
+    end
+end
+
+return pt
diff --git a/run.lua b/run.lua
new file mode 100755
index 0000000..63f3c00
--- /dev/null
+++ b/run.lua
@@ -0,0 +1,41 @@
+#!/usr/bin/lua
+local pt = require('pt')
+
+t = {
+    A = 'hello',
+    B = {
+        a = 'beep',
+        b = 'boop',
+        c = 'burp',
+    },
+    C = {
+        a = 'nude',
+        b = 'dude',
+        c = 'lewd',
+    },
+    D = 'goodbye',
+}
+t.B.d = t.C
+t.C.d = t.B
+t.E = t
+
+function dump(t, fn, seen)
+    if t == nil then return end
+
+    local file = io.open(fn, "w")
+    if not file then
+        io.write("Failed opening ", fn, "\n")
+        return
+    end
+
+    local writer = function(...)
+        file:write(...)
+    end
+    seen = pt{t, writer=writer, seen=seen}
+
+    file:close()
+    return seen
+end
+
+pt{t}
+dump(_G, '_G.yml')