diff --git a/files.lua b/files.lua
index 365cb96..ded403a 100644
--- a/files.lua
+++ b/files.lua
@@ -1,3 +1,5 @@
+local lpeg = require('lpeg')
+local re = require('re')
 local files = { }
 local _FILE_CACHE = { }
 files.spoof = function(filename, contents)
@@ -48,7 +50,7 @@ iterate_single = function(item, prev)
   end
 end
 local ok, lfs = pcall(require, "lfs")
-if ok and false then
+if ok then
   files.walk = function(path)
     local browse
     browse = function(filename)
@@ -121,4 +123,42 @@ else
     end)
   end
 end
+local line_counter = re.compile([[    lines <- {| line (%nl line)* |}
+    line <- {} (!%nl .)*
+]], {
+  nl = lpeg.P("\r") ^ -1 * lpeg.P("\n")
+})
+local get_lines = re.compile([[    lines <- {| line (%nl line)* |}
+    line <- {[^%nl]*}
+]], {
+  nl = lpeg.P("\r") ^ -1 * lpeg.P("\n")
+})
+local _LINE_STARTS = { }
+files.get_line_starts = function(str)
+  if type(str) ~= 'string' then
+    str = tostring(str)
+  end
+  do
+    local starts = _LINE_STARTS[str]
+    if starts then
+      return starts
+    end
+  end
+  local line_starts = line_counter:match(str)
+  _LINE_STARTS[str] = line_starts
+  return line_starts
+end
+files.get_line_number = function(str, pos)
+  local line_starts = files.get_line_starts(str)
+  local lo, hi = 1, #line_starts
+  while lo <= hi do
+    local mid = math.floor((lo + hi) / 2)
+    if line_starts[mid] > pos then
+      hi = mid - 1
+    else
+      lo = mid + 1
+    end
+  end
+  return hi
+end
 return files
diff --git a/files.moon b/files.moon
index 5422651..1d28e5c 100644
--- a/files.moon
+++ b/files.moon
@@ -1,4 +1,6 @@
 -- Some file utilities for searching for files recursively and using package.nomsupath
+lpeg = require 'lpeg'
+re = require 're'
 files = {}
 
 _FILE_CACHE = {}
@@ -83,4 +85,36 @@ else
             unless found
                 error("Invalid file path: "..tostring(path))
 
+line_counter = re.compile([[
+    lines <- {| line (%nl line)* |}
+    line <- {} (!%nl .)*
+]], nl:lpeg.P("\r")^-1 * lpeg.P("\n"))
+
+get_lines = re.compile([[
+    lines <- {| line (%nl line)* |}
+    line <- {[^%nl]*}
+]], nl:lpeg.P("\r")^-1 * lpeg.P("\n"))
+
+-- LINE_STARTS is a mapping from strings to a table that maps line number to character positions
+_LINE_STARTS = {}
+files.get_line_starts = (str)->
+    if type(str) != 'string'
+        str = tostring(str)
+    if starts = _LINE_STARTS[str]
+        return starts
+    line_starts = line_counter\match(str)
+    _LINE_STARTS[str] = line_starts
+    return line_starts
+
+files.get_line_number = (str, pos)->
+    line_starts = files.get_line_starts(str)
+    -- Binary search for line number of position
+    lo, hi = 1, #line_starts
+    while lo <= hi
+        mid = math.floor((lo+hi)/2)
+        if line_starts[mid] > pos
+            hi = mid-1
+        else lo = mid+1
+    return hi
+
 return files
diff --git a/nomsu_compiler.lua b/nomsu_compiler.lua
index 200f0f7..137df2e 100644
--- a/nomsu_compiler.lua
+++ b/nomsu_compiler.lua
@@ -1,6 +1,5 @@
 local lpeg = require('lpeg')
 local re = require('re')
-lpeg.setmaxstack(10000)
 local utils = require('utils')
 local files = require('files')
 local repr, stringify, equivalent
@@ -19,10 +18,10 @@ do
   insert, remove, concat = _obj_0.insert, _obj_0.remove, _obj_0.concat
 end
 local unpack = unpack or table.unpack
-local match, sub, rep, gsub, format, byte, find
+local match, sub, gsub, format, byte, find
 do
   local _obj_0 = string
-  match, sub, rep, gsub, format, byte, match, find = _obj_0.match, _obj_0.sub, _obj_0.rep, _obj_0.gsub, _obj_0.format, _obj_0.byte, _obj_0.match, _obj_0.find
+  match, sub, gsub, format, byte, find = _obj_0.match, _obj_0.sub, _obj_0.gsub, _obj_0.format, _obj_0.byte, _obj_0.find
 end
 local NomsuCode, LuaCode, Source
 do
@@ -61,46 +60,6 @@ table.fork = function(t, values)
     __index = t
   })
 end
-local line_counter = re.compile([[    lines <- {| line (%nl line)* |}
-    line <- {} (!%nl .)*
-]], {
-  nl = lpeg.P("\r") ^ -1 * lpeg.P("\n")
-})
-local get_lines = re.compile([[    lines <- {| line (%nl line)* |}
-    line <- {[^%nl]*}
-]], {
-  nl = lpeg.P("\r") ^ -1 * lpeg.P("\n")
-})
-LINE_STARTS = setmetatable({ }, {
-  __mode = "k",
-  __index = function(self, k)
-    if type(k) ~= 'string' then
-      k = tostring(k)
-      do
-        local v = rawget(self, k)
-        if v then
-          return v
-        end
-      end
-    end
-    local line_starts = line_counter:match(k)
-    self[k] = line_starts
-    return line_starts
-  end
-})
-pos_to_line = function(str, pos)
-  local line_starts = LINE_STARTS[str]
-  local lo, hi = 1, #line_starts
-  while lo <= hi do
-    local mid = math.floor((lo + hi) / 2)
-    if line_starts[mid] > pos then
-      hi = mid - 1
-    else
-      lo = mid + 1
-    end
-  end
-  return hi
-end
 do
   local STRING_METATABLE = getmetatable("")
   STRING_METATABLE.__add = function(self, other)
@@ -262,11 +221,12 @@ do
   NomsuCompiler.AST = AST
   NomsuCompiler.compile_error = function(self, tok, err_format_string, ...)
     local file = files.read(tok.source.filename)
-    local line_no = pos_to_line(file, tok.source.start)
-    local line_start = LINE_STARTS[file][line_no]
+    local line_starts = files.get_line_starts(file)
+    local line_no = files.get_line_number(file, tok.source.start)
+    local line_start = line_starts[line_no]
     local src = colored.dim(file:sub(line_start, tok.source.start - 1))
     src = src .. colored.underscore(colored.bright(colored.red(file:sub(tok.source.start, tok.source.stop - 1))))
-    local end_of_line = (LINE_STARTS[file][pos_to_line(file, tok.source.stop) + 1] or 0) - 1
+    local end_of_line = (line_starts[files.get_line_number(file, tok.source.stop) + 1] or 0) - 1
     src = src .. colored.dim(file:sub(tok.source.stop, end_of_line - 1))
     src = '    ' .. src:gsub('\n', '\n    ')
     local err_msg = err_format_string:format(src, ...)
@@ -498,7 +458,7 @@ do
       end
       local nomsu_str = tostring(file:sub(source.start, source.stop))
       local lua_line = 1
-      local nomsu_line = pos_to_line(nomsu_str, source.start)
+      local nomsu_line = files.get_line_number(nomsu_str, source.start)
       local fn
       fn = function(s)
         if type(s) == 'string' then
@@ -509,7 +469,7 @@ do
         else
           local old_line = nomsu_line
           if s.source then
-            nomsu_line = pos_to_line(nomsu_str, s.source.start)
+            nomsu_line = files.get_line_number(nomsu_str, s.source.start)
           end
           local _list_0 = s.bits
           for _index_0 = 1, #_list_0 do
@@ -629,7 +589,7 @@ do
           local bit_lua = self:compile(bit)
           if not (bit_lua.is_value) then
             local src = '    ' .. gsub(tostring(self:tree_to_nomsu(bit)), '\n', '\n    ')
-            local line = tostring(bit.source.filename) .. ":" .. tostring(pos_to_line(files.read(bit.source.filename), bit.source.start))
+            local line = tostring(bit.source.filename) .. ":" .. tostring(files.get_line_number(files.read(bit.source.filename), bit.source.start))
             self:compile_error(bit, "Cannot use:\n%s\nas a string interpolation value, since it's not an expression.")
           end
           if #lua.bits > 0 then
diff --git a/nomsu_compiler.moon b/nomsu_compiler.moon
index 99cfce7..c7105f3 100644
--- a/nomsu_compiler.moon
+++ b/nomsu_compiler.moon
@@ -11,7 +11,6 @@
 --        lua nomsu.lua your_file.nom
 lpeg = require 'lpeg'
 re = require 're'
-lpeg.setmaxstack 10000
 utils = require 'utils'
 files = require 'files'
 {:repr, :stringify, :equivalent} = utils
@@ -20,7 +19,7 @@ colors = require 'consolecolors'
 colored = setmetatable({}, {__index:(_,color)-> ((msg)-> colors[color]..tostring(msg or '')..colors.reset)})
 {:insert, :remove, :concat} = table
 unpack or= table.unpack
-{:match, :sub, :rep, :gsub, :format, :byte, :match, :find} = string
+{:match, :sub, :gsub, :format, :byte, :find} = string
 {:NomsuCode, :LuaCode, :Source} = require "code_obj"
 AST = require "nomsu_tree"
 Parser = require("parser")
@@ -50,41 +49,6 @@ table.fork = (t, values)-> setmetatable(values or {}, {__index:t})
 -- Add a ((%x foo %y) where {x:"asdf", y:"fdsa"}) compile-time action for substitution
 -- Re-implement nomsu-to-lua comment translation?
 
-line_counter = re.compile([[
-    lines <- {| line (%nl line)* |}
-    line <- {} (!%nl .)*
-]], nl:lpeg.P("\r")^-1 * lpeg.P("\n"))
-get_lines = re.compile([[
-    lines <- {| line (%nl line)* |}
-    line <- {[^%nl]*}
-]], nl:lpeg.P("\r")^-1 * lpeg.P("\n"))
--- Mapping from line number -> character offset
-export LINE_STARTS
--- LINE_STARTS is a mapping from strings to a table that maps line number to character positions
-LINE_STARTS = setmetatable {}, {
-    __mode:"k"
-    __index: (k)=>
-        -- Implicitly convert Lua and Nomsu objects to strings
-        if type(k) != 'string'
-            k = tostring(k)
-            if v = rawget(self, k)
-                return v
-        line_starts = line_counter\match(k)
-        self[k] = line_starts
-        return line_starts
-}
-export pos_to_line
-pos_to_line = (str, pos)->
-    line_starts = LINE_STARTS[str]
-    -- Binary search for line number of position
-    lo, hi = 1, #line_starts
-    while lo <= hi
-        mid = math.floor((lo+hi)/2)
-        if line_starts[mid] > pos
-            hi = mid-1
-        else lo = mid+1
-    return hi
-
 -- Use + operator for string coercive concatenation (note: "asdf" + 3 == "asdf3")
 -- Use [] for accessing string characters, or s[{3,4}] for s:sub(3,4)
 -- Note: This globally affects all strings in this instance of Lua!
@@ -158,11 +122,12 @@ with NomsuCompiler
 
     .compile_error = (tok, err_format_string, ...)=>
         file = files.read(tok.source.filename)
-        line_no = pos_to_line(file, tok.source.start)
-        line_start = LINE_STARTS[file][line_no]
+        line_starts = files.get_line_starts(file)
+        line_no = files.get_line_number(file, tok.source.start)
+        line_start = line_starts[line_no]
         src = colored.dim(file\sub(line_start, tok.source.start-1))
         src ..= colored.underscore colored.bright colored.red(file\sub(tok.source.start, tok.source.stop-1))
-        end_of_line = (LINE_STARTS[file][pos_to_line(file, tok.source.stop) + 1] or 0) - 1
+        end_of_line = (line_starts[files.get_line_number(file, tok.source.stop) + 1] or 0) - 1
         src ..= colored.dim(file\sub(tok.source.stop, end_of_line-1))
         src = '    '..src\gsub('\n', '\n    ')
         err_msg = err_format_string\format(src, ...)
@@ -336,7 +301,7 @@ with NomsuCompiler
                 error "Failed to find file: #{source.filename}"
             nomsu_str = tostring(file\sub(source.start, source.stop))
             lua_line = 1
-            nomsu_line = pos_to_line(nomsu_str, source.start)
+            nomsu_line = files.get_line_number(nomsu_str, source.start)
             fn = (s)->
                 if type(s) == 'string'
                     for nl in s\gmatch("\n")
@@ -345,7 +310,7 @@ with NomsuCompiler
                 else
                     old_line = nomsu_line
                     if s.source
-                        nomsu_line = pos_to_line(nomsu_str, s.source.start)
+                        nomsu_line = files.get_line_number(nomsu_str, s.source.start)
                     for b in *s.bits do fn(b)
             fn(lua)
             map[lua_line] or= nomsu_line
@@ -410,7 +375,7 @@ with NomsuCompiler
                     bit_lua = @compile(bit)
                     unless bit_lua.is_value
                         src = '    '..gsub(tostring(@tree_to_nomsu(bit)), '\n','\n    ')
-                        line = "#{bit.source.filename}:#{pos_to_line(files.read(bit.source.filename), bit.source.start)}"
+                        line = "#{bit.source.filename}:#{files.get_line_number(files.read(bit.source.filename), bit.source.start)}"
                         @compile_error bit,
                             "Cannot use:\n%s\nas a string interpolation value, since it's not an expression."
                     if #lua.bits > 0 then lua\append ".."
diff --git a/parser.lua b/parser.lua
index ad81252..e54ad6b 100644
--- a/parser.lua
+++ b/parser.lua
@@ -4,10 +4,10 @@ lpeg.setmaxstack(10000)
 local P, R, V, S, Cg, C, Cp, B, Cmt, Carg
 P, R, V, S, Cg, C, Cp, B, Cmt, Carg = lpeg.P, lpeg.R, lpeg.V, lpeg.S, lpeg.Cg, lpeg.C, lpeg.Cp, lpeg.B, lpeg.Cmt, lpeg.Carg
 local utils = require('utils')
-local match, sub, rep, gsub, format, byte, find
+local match, sub
 do
   local _obj_0 = string
-  match, sub, rep, gsub, format, byte, match, find = _obj_0.match, _obj_0.sub, _obj_0.rep, _obj_0.gsub, _obj_0.format, _obj_0.byte, _obj_0.match, _obj_0.find
+  match, sub = _obj_0.match, _obj_0.sub
 end
 local NomsuCode, LuaCode, Source
 do
diff --git a/parser.moon b/parser.moon
index 6fe54e6..e7ee809 100644
--- a/parser.moon
+++ b/parser.moon
@@ -4,7 +4,7 @@ re = require 're'
 lpeg.setmaxstack 10000
 {:P,:R,:V,:S,:Cg,:C,:Cp,:B,:Cmt,:Carg} = lpeg
 utils = require 'utils'
-{:match, :sub, :rep, :gsub, :format, :byte, :match, :find} = string
+{:match, :sub} = string
 {:NomsuCode, :LuaCode, :Source} = require "code_obj"
 AST = require "nomsu_tree"