diff --git a/code_obj.lua b/code_obj.lua
index de62c8f..e3f7b16 100644
--- a/code_obj.lua
+++ b/code_obj.lua
@@ -297,6 +297,12 @@ do
       end
       return statements
     end,
+    as_expr = function(self)
+      if self.is_value then
+        return self
+      end
+      return error("Cannot convert to expression: " .. tostring(tostring(self)))
+    end,
     __tostring = function(self)
       if self.__str == nil then
         local buff, indents = { }, self.indents
diff --git a/code_obj.moon b/code_obj.moon
index 73a1ba8..a5c3960 100644
--- a/code_obj.moon
+++ b/code_obj.moon
@@ -177,6 +177,11 @@ class LuaCode extends Code
         if suffix != ""
             statements\append suffix
         return statements
+    
+    as_expr: =>
+        if @is_value
+            return self
+        error("Cannot convert to expression: #{tostring self}")
 
     __tostring: =>
         if @__str == nil
diff --git a/core/control_flow.nom b/core/control_flow.nom
index 0cc8f4e..61438d1 100644
--- a/core/control_flow.nom
+++ b/core/control_flow.nom
@@ -385,16 +385,18 @@ compile [result of %body] to
     Lua value "(\(compile as: [] -> %body))()"
 
 # Recurion control flow
-using
-    compile [%var's stack] to: Lua value "stack\(%var as lua id)"
-..compile
-    parse [for %var in recursive %structure %body] as
-        with local {(%var's stack): [%structure], action: recurse % on %}
-            action [recurse %v on %x]
-                add %x to (%v's stack)
-            repeat while: (length of (%var's stack)) > 0
-                %var <- (remove 1 from (%var's stack))
-                %body
-                === next %var ==
-            === stop %var ===
-            
+compile [for %var in recursive %structure %body] to
+    with local compile actions
+        compile [recurse %v on %x] to
+            Lua "table.insert(stack\(%v as lua id), \(%x as lua expr))"
+        return
+            Lua ".."
+                do
+                    local stack\(%var as lua id) = list{\(%structure as lua expr)}
+                    while #stack\(%var as lua id) > 0 do
+                        \(%var as lua expr) = table.remove(stack\(%var as lua id), 1)
+                        \(%body as lua statements)
+                        \(compile as: === next %var ===)
+                    end
+                    \(compile as: === stop %var ===)
+                end
diff --git a/core/metaprogramming.nom b/core/metaprogramming.nom
index d22a457..242db04 100644
--- a/core/metaprogramming.nom
+++ b/core/metaprogramming.nom
@@ -61,20 +61,6 @@ compile [call %fn with %args] to
         lua:append(")")
         return lua
 
-compile [using %defs compile %body] to
-    lua> ".."
-        local lua = LuaCode(tree.source)
-        lua:append(
-            "local old_nomsu = nomsu\n",
-            "local nomsu = table.fork(old_nomsu, {COMPILE_ACTIONS=table.fork(old_nomsu.COMPILE_ACTIONS)})")
-        lua:append(nomsu:compile(\%defs))
-        lua:append("\n")
-        lua:append("local ret = nomsu:compile(tree)\n")
-        lua:append("return ret")
-        nomsu = table.fork(nomsu, {tree=\%body})
-        local output = nomsu:run_lua(lua)
-        return output
-
 compile [local action %actions %body] to
     lua> ".."
         local fn_name = "A"..string.as_lua_id(\%actions[1].stub)
@@ -138,33 +124,28 @@ compile [parse %actions as %body] to
         return ret
 
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+compile [%tree as lua expr] to
+    Lua value "nomsu:compile(\(=lua "nomsu:compile(\%tree):as_expr()")):as_expr()"
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+compile [%tree as lua] to
+    Lua value "nomsu:compile(\(%tree as lua expr))"
+
+compile [%tree as lua statements] to
+    Lua value "nomsu:compile(\(%tree as lua expr)):as_statements()"
+
+compile [%tree as lua return] to
+    Lua value "nomsu:compile(\(%tree as lua expr)):as_statements('return ')"
 
 compile [remove action %action] to
     Lua ".."
         A\(=lua "string.as_lua_id(\(%action.stub))") = nil
 
-action [%tree as nomsu]
-    =lua "nomsu:tree_to_nomsu(\%tree)"
+compile [%tree as nomsu] to
+    Lua value "nomsu:tree_to_nomsu(\(%tree as lua expr))"
 
-action [%tree as inline nomsu]
-    =lua "nomsu:tree_to_nomsu(\%tree, true)"
-
-action [%tree as lua]
-    =lua "nomsu:compile(\%tree)"
-
-action [%tree as lua expr]
-    lua> ".."
-        local lua = nomsu:compile(\%tree)
-        if not lua.is_value then
-            nomsu:compile_error(\%tree, "Invalid thing to convert to lua expr:\n%s")
-        end
-        return lua
-
-action [%tree as lua statements]
-    =lua "nomsu:compile(\%tree):as_statements()"
-
-action [%tree as lua return]
-    =lua "nomsu:compile(\%tree):as_statements('return ')"
+compile [%tree as inline nomsu] to
+    Lua value "nomsu:tree_to_nomsu(\(%tree as lua expr), true)"
 
 action [%var as lua identifier, %var as lua id]
     lua> ".."
@@ -174,6 +155,12 @@ action [%var as lua identifier, %var as lua id]
         end
 
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+compile [% is syntax tree] to
+    Lua value "AST.is_syntax_tree(\(% as lua expr))"
+
+compile [% is %kind syntax tree] to
+    Lua value "AST.is_syntax_tree(\(% as lua expr), \(%kind as lua expr))"
     
 compile [%tree with %t -> %replacement] to
     Lua value ".."
@@ -215,6 +202,10 @@ compile [parse %text] to
     Lua value ".."
         nomsu:parse(NomsuCode("\("\(%text.source)")", \(%text as lua expr)))
 
+compile [parse %text from %filename] to
+    Lua value ".."
+        nomsu:parse(NomsuCode(Source(\(%filename as lua expr), 1, #\(%text as lua expr)), \(%text as lua expr)))
+
 compile [run %nomsu_code] to
     Lua value "nomsu:run(NomsuCode(\(quote "\(%nomsu_code.source)"), \(%nomsu_code as lua expr)))"
 
@@ -238,8 +229,19 @@ compile [Nomsu syntax version] to: Lua value "NOMSU_SYNTAX_VERSION"
 compile [Nomsu compiler version] to: Lua value "NOMSU_COMPILER_VERSION"
 compile [core version] to: Lua value "NOMSU_CORE_VERSION"
 compile [lib version] to: Lua value "NOMSU_LIB_VERSION"
+compile [command line args] to: Lua value "arg"
 
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+compile [with local compile actions %body] to
+    Lua ".."
+        do
+            local nomsu = table.fork(nomsu, {COMPILE_ACTIONS=table.fork(nomsu.COMPILE_ACTIONS)})
+            \(%body as lua statements)
+        end
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
 action [Nomsu version]
     use "lib/version.nom"
     return "\(Nomsu syntax version).\(core version).\(Nomsu compiler version).\(lib version)"
diff --git a/core/operators.nom b/core/operators.nom
index 0756751..d434ea7 100644
--- a/core/operators.nom
+++ b/core/operators.nom
@@ -163,7 +163,7 @@ compile [%x ARSHIFT %shift, %x >> %shift] to: Lua value "(\(%x as lua expr) >> \
 # Unary operators
 compile [- %] to: Lua value "(- \(% as lua expr))"
 compile [not %] to: Lua value "(not \(% as lua expr))"
-compile [length of %list] to: Lua value "(#\(%list as lua expr))"
+compile [length of %list, || %list ||] to: Lua value "(#\(%list as lua expr))"
 
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/files.lua b/files.lua
index ded403a..8163ab4 100644
--- a/files.lua
+++ b/files.lua
@@ -161,4 +161,11 @@ files.get_line_number = function(str, pos)
   end
   return hi
 end
+files.get_line = function(str, line_no)
+  local line_starts = files.get_line_starts(str)
+  return str:sub(line_starts[line_no] or 1, line_starts[line_no + 1] or -1)
+end
+files.get_lines = function(str)
+  return get_lines:match(str)
+end
 return files
diff --git a/files.moon b/files.moon
index 1d28e5c..fd8a417 100644
--- a/files.moon
+++ b/files.moon
@@ -117,4 +117,10 @@ files.get_line_number = (str, pos)->
         else lo = mid+1
     return hi
 
+files.get_line = (str, line_no)->
+    line_starts = files.get_line_starts(str)
+    return str\sub(line_starts[line_no] or 1, line_starts[line_no+1] or -1)
+
+files.get_lines = (str)-> get_lines\match(str)
+
 return files
diff --git a/lib/os.nom b/lib/os.nom
index 8a27168..25b47b6 100644
--- a/lib/os.nom
+++ b/lib/os.nom
@@ -29,3 +29,8 @@ action [write to file %filename %text, to file %filename write %text]
         file:write(\%text)
         file:close()
 
+action [line number of %pos in %str]
+    =lua "files.get_line_number(\%str, \%pos)"
+    
+action [line %line_num in %str]
+    =lua "files.get_line(\%str, \%line_num)"
diff --git a/nomsu_compiler.lua b/nomsu_compiler.lua
index 137df2e..0505562 100644
--- a/nomsu_compiler.lua
+++ b/nomsu_compiler.lua
@@ -439,7 +439,7 @@ do
       local line_numbered_lua = concat((function()
         local _accum_0 = { }
         local _len_0 = 1
-        for i, line in ipairs(get_lines:match(lua_string)) do
+        for i, line in ipairs(files.get_lines(lua_string)) do
           _accum_0[_len_0] = format("%3d|%s", i, line)
           _len_0 = _len_0 + 1
         end
@@ -870,7 +870,7 @@ do
         local nomsu = NomsuCode(tree.source, '".."\n    ')
         for i, bit in ipairs(tree) do
           if type(bit) == 'string' then
-            local bit_lines = get_lines:match(bit)
+            local bit_lines = files.get_lines(bit)
             for j, line in ipairs(bit_lines) do
               if j > 1 then
                 nomsu:append("\n    ")
diff --git a/nomsu_compiler.moon b/nomsu_compiler.moon
index fdadb67..3313aa3 100644
--- a/nomsu_compiler.moon
+++ b/nomsu_compiler.moon
@@ -288,7 +288,7 @@ with NomsuCompiler
         run_lua_fn, err = load(lua_string, nil and tostring(source or lua.source), "t", self)
         if not run_lua_fn
             line_numbered_lua = concat(
-                [format("%3d|%s",i,line) for i, line in ipairs get_lines\match(lua_string)],
+                [format("%3d|%s",i,line) for i, line in ipairs files.get_lines(lua_string)],
                 "\n")
             error("Failed to compile generated code:\n#{colored.bright colored.blue colored.onblack line_numbered_lua}\n\n#{err}", 0)
         source_key = tostring(source or lua.source)
@@ -596,7 +596,7 @@ with NomsuCompiler
                     nomsu = NomsuCode(tree.source, '".."\n    ')
                     for i, bit in ipairs tree
                         if type(bit) == 'string'
-                            bit_lines = get_lines\match(bit)
+                            bit_lines = files.get_lines(bit)
                             for j, line in ipairs bit_lines
                                 if j > 1 then nomsu\append "\n    "
                                 if #line > 1.25*MAX_LINE
diff --git a/tests/control_flow.nom b/tests/control_flow.nom
index 939d5ee..340bd7d 100644
--- a/tests/control_flow.nom
+++ b/tests/control_flow.nom
@@ -179,4 +179,13 @@ assume
     ..= 6
 ..or barf "'result of %' failed"
 
+
+%t <- [1,[2,[[3],4],5,[[[6]]]]]
+%flat <- []
+for % in recursive %t
+    if: (type of %) is "table"
+        for %2 in %: recurse % on %2
+    ..else: add % to %flat
+assume: (sorted %flat) = [1,2,3,4,5,6]
+
 say "Control flow test passed."