diff --git a/code_obj.lua b/code_obj.lua
index 37ac55a..b67e78d 100644
--- a/code_obj.lua
+++ b/code_obj.lua
@@ -312,12 +312,6 @@ 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, indent = { }, 0
diff --git a/code_obj.moon b/code_obj.moon
index e1cf226..9bfa9a5 100644
--- a/code_obj.moon
+++ b/code_obj.moon
@@ -4,7 +4,6 @@
 {:insert, :remove, :concat} = table
 {:repr} = require 'utils'
 local LuaCode, NomsuCode, Source
-export LINE_STARTS
 
 class Source
     new: (@filename, @start, @stop)=>
@@ -185,11 +184,6 @@ 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/compatibility/2.nom b/compatibility/2.nom
index 35ed1a0..a93730c 100644
--- a/compatibility/2.nom
+++ b/compatibility/2.nom
@@ -4,7 +4,7 @@ use "compatibility/compatibility.nom"
 
 upgrade %tree to "2" as:
     unless (%tree is "Action" syntax tree): return
-    if (all[%tree.stub is "if % % else %", not (%tree.3 is "Var" syntax tree), not (%tree.5 is "Var" syntax tree)]):
+    if (%tree.stub is "if % % else %"):
         %true_body = (%tree.3 upgraded)
         unless (%true_body is "Block" syntax tree):
             %true_body = (=lua "Block(\%true_body.source, \%true_body)")
@@ -22,7 +22,7 @@ upgrade %tree to "2" as:
         "for % in % to % via % %", "for % in % to % %", "for % % in % %", "do %"
         "for % in recursive % %", "test %", "with % %", "result of %"
     for %n in %need_blocks:
-        if ((%tree.stub is %n) and (not ((last in %tree) is "Var" syntax tree))):
+        if (%tree.stub is %n):
             %bits = (((% upgraded) if (% is syntax tree) else %) for % in %tree)
             unless ((last in %bits) is "Block" syntax tree):
                 %body = (last in %bits)
diff --git a/compatibility/compatibility.nom b/compatibility/compatibility.nom
index 9482e32..c5ac55f 100644
--- a/compatibility/compatibility.nom
+++ b/compatibility/compatibility.nom
@@ -21,16 +21,16 @@ compile [upgrade action %action to %version as %body] to:
             %replacements.(%action.%i.1) = "\(\%tree as lua id)[\%i]"
     local action [make tree %t]:
         when:
-            * (%t is "Var" syntax tree):
+            (%t is "Var" syntax tree):
                 if (%replacements.(%t.1)):
                     return %replacements.(%t.1)
                 ..else:
                     return "\(%t.type)(\(quote "\(%t.source)"), \(quote "\(%t.1) \0\(=lua "string.format('%X', __MANGLE_INDEX)")"))"
-            * (%t is syntax tree):
+            (%t is syntax tree):
                 %args = ((make tree %) for % in %t)
                 add "\(\%tree as lua id).source" to %args at index 1
                 return "\(%t.type)(\(%args joined with ", "))"
-            *else: return (quote "\%t")
+            else: return (quote "\%t")
     return (..)
         Lua ".."
             A_upgrade_action_1_to_2_via_3(\(quote %action.stub), \(%version as lua expr), function(\(\%tree as lua id))
@@ -66,9 +66,9 @@ parse [%tree upgraded from %start_version] as (..)
     %tree upgraded from %start_version to (Nomsu version)
 
 parse [%tree upgraded to %end_version] as (..)
-    %tree upgraded from %tree.version to %end_version
+    %tree upgraded from (%tree.version or "0") to %end_version
 
-parse [%tree upgraded] as (%tree upgraded from %tree.version to (Nomsu version))
+parse [%tree upgraded] as (%tree upgraded from (%tree.version or "0") to (Nomsu version))
 action [use %path from version %version] (..)
     for file %filename in %path:
         if (=lua "LOADED[\%filename]"): do next %filename
diff --git a/core/collections.nom b/core/collections.nom
index 45ca74c..428ed4d 100644
--- a/core/collections.nom
+++ b/core/collections.nom
@@ -1,4 +1,4 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 #
     This file contains code that supports manipulating and using collections like lists
     and dictionaries.
diff --git a/core/control_flow.nom b/core/control_flow.nom
index b3f0978..5719d72 100644
--- a/core/control_flow.nom
+++ b/core/control_flow.nom
@@ -154,7 +154,7 @@ compile [..]
 ..to:
     
     # This uses Lua's approach of only allowing loop-scoped variables in a loop
-    assume (%var.type is "Var") or barf "Loop expected variable, not: \%var"
+    unless (%var.type is "Var"): compile error at %var.source "Loop expected variable, not: %s"
     %lua = (..)
         Lua ".."
             for \(%var as lua expr)=\(%start as lua expr),\(%stop as lua expr),\(%step as lua expr) do
@@ -185,12 +185,11 @@ compile [..]
 parse [for %var in %start to %stop %body] as (..)
     for %var in %start to %stop via 1 %body
 
-
 # For-each loop (lua's "ipairs()")
 compile [for %var in %iterable %body] to:
     
     # This uses Lua's approach of only allowing loop-scoped variables in a loop
-    assume (%var.type is "Var") or barf "Loop expected variable, not: \%var"
+    unless (%var.type is "Var"): compile error at %var.source "Loop expected variable, not: %s"
     %lua = (..)
         Lua ".."
             for i,\(%var as lua identifier) in ipairs(\(%iterable as lua expr)) do
@@ -223,8 +222,8 @@ compile [for %key = %value in %iterable %body, for %key %value in %iterable %bod
 ..to:
     
     # This uses Lua's approach of only allowing loop-scoped variables in a loop
-    assume (%key.type is "Var") or barf "Loop expected variable, not: \%key"
-    assume (%value.type is "Var") or barf "Loop expected variable, not: \%value"
+    unless (%key.type is "Var"): compile error at %key.source "Loop expected variable, not: %s"
+    unless (%value.type is "Var"): compile error at %value.source "Loop expected variable, not: %s"
     %lua = (..)
         Lua ".."
             for \(%key as lua identifier),\(%value as lua identifier) in pairs(\(%iterable as lua expr)) do
@@ -266,101 +265,88 @@ compile [for %key = %value in %iterable %body, for %key %value in %iterable %bod
 
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-# Switch statement/multi-branch if
-compile [when %body] to:
+# Multi-branch conditional (if..elseif..else)
+compile [if %body, when %body] to:
     %code = (Lua "")
-    %fallthroughs = []
-    %is_first = (yes)
-    %seen_else = (no)
-    %branches = (%body if (%body.type == "Block") else [%body])
-    for %func_call in %branches:
-        assume (%func_call.type is "Action") or barf "Invalid format for 'when' statement. Only '*' blocks are allowed."
-        with {%star: %func_call.1, %condition: %func_call.2, %action: %func_call.3}:
-            assume (%star == "*") or barf "Invalid format for 'when' statement. Lines must begin with '*'"
-            assume %condition or barf ".."
-                Invalid format for 'when' statement. Lines must begin with '*' and have a condition \
-                ..or the word "else"
-            
-            if (%action is (nil)):
-                lua> "table.insert(\%fallthroughs, \(%condition as lua expr))"
-                do next %func_call
-            
-            if (%condition == "else"):
-                assume (not %is_first) or barf "'else' clause cannot be first in 'when % = ?' block"
-                to %code write "\nelse\n    "
-                to %code write (%action as lua statements)
-                %seen_else = (yes)
-            ..else:
-                assume (not %seen_else) or barf "'else' clause needs to be last in 'when' block"
-                lua> "table.insert(\%fallthroughs, \(%condition as lua expr))"
-                to %code write "\("if" if %is_first else "\nelseif") "
-                for %i = %condition in %fallthroughs:
-                    if (%i > 1): to %code write " or "
-                    to %code write %condition
-                
-                to %code write " then\n    "
-                to %code write (%action as lua statements)
-            
-            %fallthroughs = []
-            %is_first = (no)
+    %clause = "if"
+    %else_allowed = (yes)
+    unless (%body.type is "Block"): compile error at %body.source "'if' expected a Block, but got: %s"
+    for %line in %body:
+        unless (..)
+            ((%line.type is "Action") and ((length of %line) >= 2))
+            ..and (%line.(length of %line) is "Block" syntax tree)
+        ..:
+            compile error at %line.source ".."
+                Invalid line for 'if', each line should contain conditional expressions \
+                ..followed by a block, or "else" followed by a block:
+                %s
+        %action = %line.(length of %line)
+        if ((%line.1 is "else") and ((length of %line) == 2)):
+            unless %else_allowed: compile error at %line.source "Can't have two 'else' blocks"
+            unless ((length of "\%code") > 0):
+                compile error at %line.source "Can't have an 'else' block without a preceeding condition"
+            to %code write "\nelse\n    \(%action as lua statements)"
+            %else_allowed = (no)
+        ..else:
+            to %code write "\%clause "
+            for %i in 1 to ((length of %line) - 1):
+                unless (%line.%i is syntax tree):
+                    compile error at %line.source ".."
+                        Invalid condition for 'if' statement:
+                        %s
+                if (%i > 1): to %code write " or "
+                to %code write (%line.%i as lua expr)
+            to %code write " then\n    \(%action as lua statements)"
+            %clause = "\nelseif"
     
-    assume (%fallthroughs == []) or barf "Unfinished fallthrough conditions in 'when' block"
-    assume ((length of "\%code") > 0) or barf "Empty body for 'when' block"
+    if ((length of "\%code") == 0):
+        compile error at %body.source "'if' block has an empty body"
     to %code write "\nend --when"
     return %code
 
-
 # Switch statement
-compile [when %branch_value = ? %body, when %branch_value is? %body] to:
+compile [if %branch_value is %body, when %branch_value is %body] to:
     %code = (Lua "")
-    %fallthroughs = []
-    %is_first = (yes)
-    %seen_else = (no)
-    %branches = (%body if (%body.type == "Block") else [%body])
-    for %func_call in %branches:
-        assume (%func_call.type is "Action") or barf "Invalid format for 'when' statement. Only '*' blocks are allowed."
-        with {%star: %func_call.1, %condition: %func_call.2, %action: %func_call.3}:
-            assume (%star == "*") or barf "Invalid format for 'when' statement. Lines must begin with '*'"
-            assume %condition or barf ".."
-                Invalid format for 'when' statement. Lines must begin with '*' and have a condition \
-                ..or the word "else"
-            
-            if (%action is (nil)):
-                lua> "table.insert(\%fallthroughs, \(%condition as lua expr))"
-                do next %func_call
-            
-            if (%condition == "else"):
-                assume (not %is_first) or barf "'else' clause cannot be first in 'when % = ?' block"
-                to %code write "\nelse\n    "
-                to %code write (%action as lua statements)
-            ..else:
-                assume (not %seen_else) or barf "'else' clause needs to be last in 'when % = ?' block"
-                to %code write "\("if" if %is_first else "\nelseif") "
-                lua> "table.insert(\%fallthroughs, \(%condition as lua expr))"
-                for %i = % in %fallthroughs:
-                    if (%i > 1): to %code write " or "
-                    if ((%.type is "Text") or (%.type is "Number")):
-                        to %code write "branch_value == \%"
-                    ..else: to %code write "utils.equivalent(branch_value, \%)"
-                
-                to %code write "then\n    "
-                to %code write (%action as lua statements)
-        
-        %fallthroughs = []
-        %is_first = (no)
+    %clause = "if"
+    %else_allowed = (yes)
+    unless (%body.type is "Block"): compile error at %body.source "'if' expected a Block, but got: %s"
+    for %line in %body:
+        unless (..)
+            ((%line.type is "Action") and ((length of %line) >= 2))
+            ..and (%line.(length of %line) is "Block" syntax tree)
+        ..:
+            compile error at %line.source ".."
+                Invalid line for 'if % is % %', each line should contain expressions \
+                ..followed by a block, or "else" followed by a block:
+                %s
+        %action = %line.(length of %line)
+        if ((%line.1 is "else") and ((length of %line) == 2)):
+            unless %else_allowed: compile error at %line.source "Can't have two 'else' blocks"
+            unless ((length of "\%code") > 0):
+                compile error at %line.source "Can't have an 'else' block without a preceeding condition"
+            to %code write "\nelse\n    \(%action as lua statements)"
+            %else_allowed = (no)
+        ..else:
+            to %code write "\%clause "
+            for %i in 1 to ((length of %line) - 1):
+                unless (%line.%i is syntax tree):
+                    compile error at %line.source ".."
+                        Invalid condition for 'if' statement:
+                        %s
+                if (%i > 1): to %code write " or "
+                to %code write "branch_value == \(%line.%i as lua expr)"
+            to %code write " then\n    \(%action as lua statements)"
+            %clause = "\nelseif"
     
-    assume (%fallthroughs == []) or barf "Unfinished fallthrough conditions in 'when' block"
-    assume ((length of "\%code") > 0) or barf "No body for 'when % = ?' block!"
-    to %code write "\nend"
-    %code = (..)
+    if ((length of "\%code") == 0):
+        compile error at %body.source "'if % is % %' block has an empty body"
+    to %code write "\nend --when"
+    return (..)
         Lua ".."
-            do --when % = ?
+            do --if % is
                 local branch_value = \(%branch_value as lua expr)
                 \%code
-            end --when % = ?
-    
-    return %code
-
+            end --if % is
 
 # Do/finally
 compile [do %action] to (..)
diff --git a/core/coroutines.nom b/core/coroutines.nom
index 54889d4..bff115d 100644
--- a/core/coroutines.nom
+++ b/core/coroutines.nom
@@ -1,4 +1,4 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 #
     This file defines the code that creates and manipulates coroutines
 
diff --git a/core/errors.nom b/core/errors.nom
index efa69a8..5dfed1e 100644
--- a/core/errors.nom
+++ b/core/errors.nom
@@ -1,4 +1,4 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 #
     This file contains basic error reporting code
 
@@ -7,6 +7,9 @@ compile [traceback] to (Lua value "debug.traceback()")
 compile [traceback %] to (Lua value "debug.traceback('', \(% as lua expr))")
 compile [barf] to (Lua "error(nil, 0);")
 compile [barf %msg] to (Lua "error(\(%msg as lua expr), 0);")
+compile [compile error at %source %msg] to (..)
+    Lua "nomsu:compile_error(\(%source as lua expr), \(%msg as lua expr))"
+
 compile [assume %condition] to:
     lua> ".."
         local \%assumption = 'Assumption failed: '..tostring(nomsu:tree_to_nomsu(\%condition))
diff --git a/core/io.nom b/core/io.nom
index 2659b3b..b06ebb3 100644
--- a/core/io.nom
+++ b/core/io.nom
@@ -1,4 +1,4 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 #
     This file contains basic input/output code
 
diff --git a/core/math.nom b/core/math.nom
index d8952f6..e0c58a3 100644
--- a/core/math.nom
+++ b/core/math.nom
@@ -1,4 +1,4 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 #
     This file defines some common math literals and functions
 
diff --git a/core/metaprogramming.nom b/core/metaprogramming.nom
index 8328d26..028a914 100644
--- a/core/metaprogramming.nom
+++ b/core/metaprogramming.nom
@@ -1,9 +1,9 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 #
     This File contains actions for making actions and compile-time actions and some helper
     functions to make that easier.
 
-lua> "NOMSU_CORE_VERSION = 3"
+lua> "NOMSU_CORE_VERSION = 4"
 lua> ".."
     nomsu.COMPILE_ACTIONS["% -> %"] = function(nomsu, tree, \%args, \%body)
         local lua = LuaCode.Value(tree.source, "function(")
@@ -119,8 +119,16 @@ compile [parse %actions as %body] to (..)
         local ret = \(compile as (compile %actions to %new_body))
         return ret
 
-compile [%tree as lua expr] to (..)
-    Lua value "nomsu:compile(\(=lua "nomsu:compile(\%tree):as_expr()")):as_expr()"
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+action [%tree as lua expr]:
+    lua> ".."
+        \%tree_lua = nomsu:compile(\%tree)
+        if not \%tree_lua.is_value then
+            nomsu:compile_error(\%tree.source, "Could not convert %s to a Lua expression",
+                nomsu:tree_to_nomsu(\%tree))
+        end
+        return \%tree_lua
 
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/core/operators.nom b/core/operators.nom
index 70b0207..bce91c4 100644
--- a/core/operators.nom
+++ b/core/operators.nom
@@ -1,4 +1,4 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 #
     This file contains definitions of operators like "+" and "and".
 
@@ -147,21 +147,29 @@ compile [%x wrapped around %y, %x mod %y] to (..)
 # (uses a lambda to avoid re-evaluating middle value, while still being an expression)
 parse [%x < %y < %z] as (..)
     =lua "(function(x,y,z) return x <  y and y <  z; end)(\%x,\%y,\%z)"
+
 parse [%x <= %y < %z] as (..)
     =lua "(function(x,y,z) return x <= y and y <  z; end)(\%x,\%y,\%z)"
+
 parse [%x < %y <= %z] as (..)
     =lua "(function(x,y,z) return x <  y and y <= z; end)(\%x,\%y,\%z)"
+
 parse [%x <= %y <= %z] as (..)
     =lua "(function(x,y,z) return x <= y and y <= z; end)(\%x,\%y,\%z)"
+
 parse [%x > %y > %z] as (..)
     =lua "(function(x,y,z) return x >  y and y >  z; end)(\%x,\%y,\%z)"
+
 parse [%x >= %y > %z] as (..)
     =lua "(function(x,y,z) return x >= y and y >  z; end)(\%x,\%y,\%z)"
+
 parse [%x > %y >= %z] as (..)
     =lua "(function(x,y,z) return x >  y and y >= z; end)(\%x,\%y,\%z)"
+
 parse [%x >= %y >= %z] as (..)
     =lua "(function(x,y,z) return x >= y and y >= z; end)(\%x,\%y,\%z)"
 
+
 # TODO: optimize for common case where x,y,z are all either variables or number literals
 # Boolean Operators
 compile [%x and %y] to (Lua value "(\(%x as lua expr) and \(%y as lua expr))")
@@ -204,4 +212,4 @@ parse [%var /= %] as (%var = (%var / %))
 parse [%var ^= %] as (%var = (%var ^ %))
 parse [%var and= %] as (%var = (%var and %))
 parse [%var or= %] as (%var = (%var or %))
-parse [wrap %var around %] as (%var = (%var wrapped around %))
+parse [wrap %var around %] as (%var = (%var wrapped around %))
\ No newline at end of file
diff --git a/core/scopes.nom b/core/scopes.nom
index 2be24e6..30bdea0 100644
--- a/core/scopes.nom
+++ b/core/scopes.nom
@@ -1,4 +1,4 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 #
     This file contains definitions pertaining to variable scoping
 
@@ -8,17 +8,16 @@ use "core/collections.nom"
 use "core/control_flow.nom"
 compile [with local %locals %body, with local %locals do %body] to:
     %body_lua = (%body as lua statements)
-    when %locals.type = ?:
-        * "Dict":
+    if %locals.type is:
+        "Dict":
             %body_lua = (..)
                 Lua "\(compile as (<- %locals))\n\%body_lua"
             
             declare locals ("\(%.1 as lua)" for % in %locals) in %body_lua
         
-        * "List": declare locals ("\(% as lua)" for % in %locals) in %body_lua
-        * "Var"
-        * "Action": declare locals ["\(%locals as lua)"] in %body_lua
-        *else (barf "Unexpected local: \(%locals as nomsu)")
+        "List": declare locals ("\(% as lua)" for % in %locals) in %body_lua
+        "Var" "Action": declare locals ["\(%locals as lua)"] in %body_lua
+        else: compile error at %locals.source "Unexpected locals: %s"
     
     return (..)
         Lua "do\n    \%body_lua\nend"
\ No newline at end of file
diff --git a/core/text.nom b/core/text.nom
index 62ec056..30eab50 100644
--- a/core/text.nom
+++ b/core/text.nom
@@ -1,4 +1,4 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 #
     This file contains some definitions of text escape sequences, including ANSI console
     color codes.
diff --git a/lib/consolecolor.nom b/lib/consolecolor.nom
index 39bae68..6e327ff 100644
--- a/lib/consolecolor.nom
+++ b/lib/consolecolor.nom
@@ -1,4 +1,4 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 #
     This file defines actions for ANSI console color escape codes.
 
diff --git a/lib/file_hash.nom b/lib/file_hash.nom
index 283c5b4..49c768f 100644
--- a/lib/file_hash.nom
+++ b/lib/file_hash.nom
@@ -1,4 +1,4 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 #
     This file defines some actions for hashing files and looking up files by hash.
 
diff --git a/lib/object.nom b/lib/object.nom
index cb5cd3c..ae52d99 100644
--- a/lib/object.nom
+++ b/lib/object.nom
@@ -1,4 +1,4 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 #
     This file contains the implementation of an Object-Oriented programming system.
 
diff --git a/lib/os.nom b/lib/os.nom
index 57dac26..e29b5d1 100644
--- a/lib/os.nom
+++ b/lib/os.nom
@@ -1,4 +1,4 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 #
     This file defines some actions that interact with the operating system and filesystem.
 
diff --git a/lib/training_wheels.nom b/lib/training_wheels.nom
index 4c0b166..2845768 100644
--- a/lib/training_wheels.nom
+++ b/lib/training_wheels.nom
@@ -1,4 +1,4 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 #
     This file contains a set of definitions that bring some familiar language features
     from other languages into nomsu (e.g. "==" and "continue")
@@ -11,7 +11,7 @@ parse [%a === %b] as ((%a 's id) is (%b 's id))
 parse [%a !== %b] as ((%a 's id) is not (%b 's id))
 parse [%a mod %b] as (%a wrapped around %b)
 parse [function %names %body, def %names %body] as (action %names %body)
-parse [switch %branch_value %body] as (when %branch_value = ? %body)
+parse [switch %branch_value %body] as (if %branch_value is: %body)
 parse [None, Null] as (nil)
 parse [True, true] as (yes)
 parse [False, false] as (no)
diff --git a/lib/version.nom b/lib/version.nom
index 952d940..3380301 100644
--- a/lib/version.nom
+++ b/lib/version.nom
@@ -1,3 +1,3 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 # This file sets the current library version.
 lua> "NOMSU_LIB_VERSION = 3"
\ No newline at end of file
diff --git a/nomsu_compiler.lua b/nomsu_compiler.lua
index da4a155..b4702ed 100644
--- a/nomsu_compiler.lua
+++ b/nomsu_compiler.lua
@@ -227,18 +227,19 @@ do
   })
   NomsuCompiler.LOADED = { }
   NomsuCompiler.AST = AST
-  NomsuCompiler.compile_error = function(self, tok, err_format_string, ...)
-    local file = files.read(tok.source.filename)
+  NomsuCompiler.compile_error = function(self, source, err_format_string, ...)
+    err_format_string = err_format_string:gsub("%%[^s]", "%%%1")
+    local file = files.read(source.filename)
     local line_starts = files.get_line_starts(file)
-    local line_no = files.get_line_number(file, tok.source.start)
+    local line_no = files.get_line_number(file, 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[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))
+    local src = colored.dim(file:sub(line_start, source.start - 1))
+    src = src .. colored.underscore(colored.bright(colored.red(file:sub(source.start, source.stop - 1))))
+    local end_of_line = (line_starts[files.get_line_number(file, source.stop) + 1] or 0) - 1
+    src = src .. colored.dim(file:sub(source.stop, end_of_line - 1))
     src = '    ' .. src:gsub('\n', '\n    ')
     local err_msg = err_format_string:format(src, ...)
-    return error(tostring(tok.source.filename) .. ":" .. tostring(line_no) .. ": " .. err_msg, 0)
+    return error(tostring(source.filename) .. ":" .. tostring(line_no) .. ": " .. err_msg, 0)
   end
   local math_expression = re.compile([[ ([+-] " ")* "%" (" " [*/^+-] (" " [+-])* " %")+ !. ]])
   local add_lua_bits
@@ -256,7 +257,7 @@ do
         else
           local bit_lua = self:compile(bit)
           if not (bit_lua.is_value) then
-            self:compile_error(bit, "Cannot use:\n%s\nas a string interpolation value, since it's not an expression.")
+            self:compile_error(bit.source, "Cannot use:\n%s\nas a string interpolation value, since it's not an expression.")
           end
           lua:append(bit_lua)
         end
@@ -289,7 +290,7 @@ do
         else
           local bit_lua = self:compile(bit)
           if not (bit_lua.is_value) then
-            self:compile_error(bit, "Cannot use:\n%s\nas a string interpolation value, since it's not an expression.")
+            self:compile_error(bit.source, "Cannot use:\n%s\nas a string interpolation value, since it's not an expression.")
           end
           add_bit_lua(lua, bit_lua)
         end
@@ -308,7 +309,7 @@ do
         else
           local tok_lua = self:compile(tok)
           if not (tok_lua.is_value) then
-            self:compile_error(tok, "Non-expression value inside math expression:\n%s")
+            self:compile_error(tok.source, "Non-expression value inside math expression:\n%s")
           end
           if tok.type == "Action" then
             tok_lua:parenthesize()
@@ -456,7 +457,7 @@ do
       source = nil
     end
     local lua_string = tostring(lua)
-    local run_lua_fn, err = load(lua_string, tostring(source or lua.source), "t", self)
+    local run_lua_fn, err = load(lua_string, nil and tostring(source or lua.source), "t", self)
     if not run_lua_fn then
       local line_numbered_lua = concat((function()
         local _accum_0 = { }
@@ -540,7 +541,7 @@ do
           end
           local ret = compile_action(self, tree, unpack(args))
           if not ret then
-            self:compile_error(tree, "Compile-time action:\n%s\nfailed to produce any Lua")
+            self:compile_error(tree.source, "Compile-time action:\n%s\nfailed to produce any Lua")
           end
           return ret
         end
@@ -556,7 +557,7 @@ do
           end
           local arg_lua = self:compile(tok)
           if not (arg_lua.is_value) then
-            self:compile_error(tok, "Cannot use:\n%s\nas an argument to %s, since it's not an expression, it produces: %s", stub, repr(arg_lua))
+            self:compile_error(tok.source, "Cannot use:\n%s\nas an argument to %s, since it's not an expression, it produces: %s", stub, repr(arg_lua))
           end
           insert(args, arg_lua)
           _continue_0 = true
@@ -624,7 +625,7 @@ do
           if not (bit_lua.is_value) then
             local src = '    ' .. gsub(tostring(recurse(bit)), '\n', '\n    ')
             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.")
+            self:compile_error(bit.source, "Cannot use:\n%s\nas a string interpolation value, since it's not an expression.")
           end
           if #lua.bits > 0 then
             lua:append("..")
@@ -655,7 +656,7 @@ do
       for i, item in ipairs(tree) do
         local item_lua = self:compile(item)
         if not (item_lua.is_value) then
-          self:compile_error(item, "Cannot use:\n%s\nas a list item, since it's not an expression.")
+          self:compile_error(item.source, "Cannot use:\n%s\nas a list item, since it's not an expression.")
         end
         items[i] = item_lua
       end
@@ -680,11 +681,11 @@ do
       local key, value = tree[1], tree[2]
       local key_lua = self:compile(key)
       if not (key_lua.is_value) then
-        self:compile_error(tree[1], "Cannot use:\n%s\nas a dict key, since it's not an expression.")
+        self:compile_error(tree[1].source, "Cannot use:\n%s\nas a dict key, since it's not an expression.")
       end
       local value_lua = value and self:compile(value) or LuaCode.Value(key.source, "true")
       if not (value_lua.is_value) then
-        self:compile_error(tree[2], "Cannot use:\n%s\nas a dict value, since it's not an expression.")
+        self:compile_error(tree[2].source, "Cannot use:\n%s\nas a dict value, since it's not an expression.")
       end
       local key_str = match(tostring(key_lua), [=[["']([a-zA-Z_][a-zA-Z0-9_]*)['"]]=])
       if key_str then
@@ -697,7 +698,7 @@ do
     elseif "IndexChain" == _exp_0 then
       local lua = self:compile(tree[1])
       if not (lua.is_value) then
-        self:compile_error(tree[1], "Cannot index:\n%s\nsince it's not an expression.")
+        self:compile_error(tree[1].source, "Cannot index:\n%s\nsince it's not an expression.")
       end
       local first_char = sub(tostring(lua), 1, 1)
       if first_char == "{" or first_char == '"' or first_char == "[" then
@@ -707,7 +708,7 @@ do
         local key = tree[i]
         local key_lua = self:compile(key)
         if not (key_lua.is_value) then
-          self:compile_error(key, "Cannot use:\n%s\nas an index, since it's not an expression.")
+          self:compile_error(key.source, "Cannot use:\n%s\nas an index, since it's not an expression.")
         end
         local key_lua_str = tostring(key_lua)
         do
@@ -833,7 +834,7 @@ do
         return nomsu
       else
         local pos = tree.source.start
-        local nomsu = NomsuCode(tree.source, pop_comments(pos, '\n'))
+        local nomsu = NomsuCode(tree.source, pop_comments(pos))
         local next_space = ""
         for i, bit in ipairs(tree) do
           if match(next_space, '\n') then
diff --git a/nomsu_compiler.moon b/nomsu_compiler.moon
index dd08994..5b9b3f6 100644
--- a/nomsu_compiler.moon
+++ b/nomsu_compiler.moon
@@ -124,18 +124,19 @@ with NomsuCompiler
     .LOADED = {}
     .AST = AST
 
-    .compile_error = (tok, err_format_string, ...)=>
-        file = files.read(tok.source.filename)
+    .compile_error = (source, err_format_string, ...)=>
+        err_format_string = err_format_string\gsub("%%[^s]", "%%%1")
+        file = files.read(source.filename)
         line_starts = files.get_line_starts(file)
-        line_no = files.get_line_number(file, tok.source.start)
+        line_no = files.get_line_number(file, 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[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 = colored.dim(file\sub(line_start, source.start-1))
+        src ..= colored.underscore colored.bright colored.red(file\sub(source.start, source.stop-1))
+        end_of_line = (line_starts[files.get_line_number(file, source.stop) + 1] or 0) - 1
+        src ..= colored.dim(file\sub(source.stop, end_of_line-1))
         src = '    '..src\gsub('\n', '\n    ')
         err_msg = err_format_string\format(src, ...)
-        error("#{tok.source.filename}:#{line_no}: "..err_msg, 0)
+        error("#{source.filename}:#{line_no}: "..err_msg, 0)
 
     -- This is a bit of a hack, but this code handles arbitrarily complex
     -- math expressions like 2*x + 3^2 without having to define a single
@@ -154,7 +155,7 @@ with NomsuCompiler
                 else
                     bit_lua = @compile(bit)
                     unless bit_lua.is_value
-                        @compile_error bit,
+                        @compile_error bit.source,
                             "Cannot use:\n%s\nas a string interpolation value, since it's not an expression."
                     lua\append bit_lua
             return lua
@@ -178,7 +179,7 @@ with NomsuCompiler
                 else
                     bit_lua = @compile(bit)
                     unless bit_lua.is_value
-                        @compile_error bit,
+                        @compile_error bit.source,
                             "Cannot use:\n%s\nas a string interpolation value, since it's not an expression."
                     add_bit_lua(lua, bit_lua)
             lua\append ")"
@@ -194,7 +195,7 @@ with NomsuCompiler
                 else
                     tok_lua = @compile(tok)
                     unless tok_lua.is_value
-                        @compile_error tok, "Non-expression value inside math expression:\n%s"
+                        @compile_error tok.source, "Non-expression value inside math expression:\n%s"
                     if tok.type == "Action"
                         tok_lua\parenthesize!
                     lua\append tok_lua
@@ -293,7 +294,7 @@ with NomsuCompiler
 
     .run_lua = (lua, source=nil)=>
         lua_string = tostring(lua)
-        run_lua_fn, err = load(lua_string, tostring(source or lua.source), "t", self)
+        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 files.get_lines(lua_string)],
@@ -340,7 +341,7 @@ with NomsuCompiler
                     -- TODO: use tail call?
                     ret = compile_action(@, tree, unpack(args))
                     if not ret
-                        @compile_error tree,
+                        @compile_error tree.source,
                             "Compile-time action:\n%s\nfailed to produce any Lua"
                     return ret
 
@@ -350,7 +351,7 @@ with NomsuCompiler
                     if type(tok) == "string" then continue
                     arg_lua = @compile(tok)
                     unless arg_lua.is_value
-                        @compile_error tok,
+                        @compile_error tok.source,
                             "Cannot use:\n%s\nas an argument to %s, since it's not an expression, it produces: %s",
                             stub, repr arg_lua
                     insert args, arg_lua
@@ -387,7 +388,7 @@ with NomsuCompiler
                     unless bit_lua.is_value
                         src = '    '..gsub(tostring(recurse(bit)), '\n','\n    ')
                         line = "#{bit.source.filename}:#{files.get_line_number(files.read(bit.source.filename), bit.source.start)}"
-                        @compile_error bit,
+                        @compile_error bit.source,
                             "Cannot use:\n%s\nas a string interpolation value, since it's not an expression."
                     if #lua.bits > 0 then lua\append ".."
                     if bit.type != "Text"
@@ -408,7 +409,7 @@ with NomsuCompiler
                 for i, item in ipairs tree
                     item_lua = @compile(item)
                     unless item_lua.is_value
-                        @compile_error item,
+                        @compile_error item.source,
                             "Cannot use:\n%s\nas a list item, since it's not an expression."
                     items[i] = item_lua
                 lua\concat_append(items, ", ", ",\n  ")
@@ -425,11 +426,11 @@ with NomsuCompiler
                 key, value = tree[1], tree[2]
                 key_lua = @compile(key)
                 unless key_lua.is_value
-                    @compile_error tree[1],
+                    @compile_error tree[1].source,
                         "Cannot use:\n%s\nas a dict key, since it's not an expression."
                 value_lua = value and @compile(value) or LuaCode.Value(key.source, "true")
                 unless value_lua.is_value
-                    @compile_error tree[2],
+                    @compile_error tree[2].source,
                         "Cannot use:\n%s\nas a dict value, since it's not an expression."
                 -- TODO: support arbitrary words here, like operators and unicode
                 key_str = match(tostring(key_lua), [=[["']([a-zA-Z_][a-zA-Z0-9_]*)['"]]=])
@@ -446,7 +447,7 @@ with NomsuCompiler
             when "IndexChain"
                 lua = @compile(tree[1])
                 unless lua.is_value
-                    @compile_error tree[1],
+                    @compile_error tree[1].source,
                         "Cannot index:\n%s\nsince it's not an expression."
                 first_char = sub(tostring(lua),1,1)
                 if first_char == "{" or first_char == '"' or first_char == "["
@@ -456,7 +457,7 @@ with NomsuCompiler
                     key = tree[i]
                     key_lua = @compile(key)
                     unless key_lua.is_value
-                        @compile_error key,
+                        @compile_error key.source,
                             "Cannot use:\n%s\nas an index, since it's not an expression."
                     key_lua_str = tostring(key_lua)
                     if lua_id = match(key_lua_str, "^['\"]([a-zA-Z_][a-zA-Z0-9_]*)['\"]$")
@@ -539,7 +540,7 @@ with NomsuCompiler
                     return nomsu
                 else
                     pos = tree.source.start
-                    nomsu = NomsuCode(tree.source, pop_comments(pos, '\n'))
+                    nomsu = NomsuCode(tree.source, pop_comments(pos))
                     next_space = ""
                     for i,bit in ipairs tree
                         if match(next_space, '\n')
diff --git a/tests/collections.nom b/tests/collections.nom
index cf60ebe..f8b813f 100644
--- a/tests/collections.nom
+++ b/tests/collections.nom
@@ -1,4 +1,4 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 #..
     Tests for the stuff defined in core/control_flow.nom
 use "core"
diff --git a/tests/colors.nom b/tests/colors.nom
index d4d5ac5..da1b2e3 100644
--- a/tests/colors.nom
+++ b/tests/colors.nom
@@ -1,3 +1,3 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 use "lib/consolecolor.nom"
 say (bright (green "Color test passed."))
\ No newline at end of file
diff --git a/tests/control_flow.nom b/tests/control_flow.nom
index 1d223a4..6312d77 100644
--- a/tests/control_flow.nom
+++ b/tests/control_flow.nom
@@ -1,4 +1,4 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 #
     Tests for the stuff defined in core/control_flow.nom
 
@@ -107,37 +107,35 @@ for %key = %value in {x: 1, y: 2}:
     do next %value
     barf "skipping value failed"
 
-action [barfer] (barf "this should never be reached")
-when:
-    * (no) (barf "'when' fail")
-    * (no)
-    * (3 > 4) (barf "'when' fail 2")
-    * (yes)
-    * (barfer) (do nothing)
-    * (99 > 1) (barf "Fell through incorrectly")
+action [barfer]: barf "this should never be reached"
+if:
+    (no): barf "'when' fail"
+    (no) (3 > 4): barf "'when' fail 2"
+    (yes) (barfer): do nothing
+    (99 > 1): barf "Fell through incorrectly"
 
 %else_worked = (no)
-when:
-    * (no) (barf)
-    *else (%else_worked = (yes))
+if:
+    (no): barf
+    else: %else_worked = (yes)
+
+
 
 assume %else_worked or barf "when..else failed"
-action [test when scope] (when (* (yes) (%leaked = (yes))))
+action [test when scope]:
+    if (yes): %leaked = (yes)
 test when scope
 assume (not %leaked) or barf "'when' is leaking locals"
 %when_worked = (no)
-when 4 = ?:
-    * 1
-    * 2 (barf "'when = ?' fail")
-    * 3
-    * 4
-    * (barfer) (%when_worked = (yes))
+if 4 is:
+    1 2: barf "'when = ?' fail"
+    3 4 (barfer): %when_worked = (yes)
 
 assume %when_worked
 %when_worked = (no)
-when 5 = ?:
-    * 6 (barf)
-    *else (%when_worked = (yes))
+if 5 is:
+    6: barf
+    else: %when_worked = (yes)
 
 assume %when_worked
 %x = 1
@@ -149,8 +147,7 @@ assume (..)
             %n = 0
             for % in [1, 2, 3]: %n += %
             return %n
-    ..== 6
-
+    .. == 6
 %t = [1, [2, [[3], 4], 5, [[[6]]]]]
 %flat = []
 for % in recursive %t:
diff --git a/tests/coroutines.nom b/tests/coroutines.nom
index 54b233e..a67e1c8 100644
--- a/tests/coroutines.nom
+++ b/tests/coroutines.nom
@@ -1,4 +1,4 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 #
     Tests for the stuff defined in core/control_flow.nom
 
diff --git a/tests/errors.nom b/tests/errors.nom
index 7f91c88..af918a6 100644
--- a/tests/errors.nom
+++ b/tests/errors.nom
@@ -1,4 +1,4 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 #
     Tests for the stuff defined in core/errors.nom
 
diff --git a/tests/inner/inner.nom b/tests/inner/inner.nom
index a4341f0..903e0c0 100644
--- a/tests/inner/inner.nom
+++ b/tests/inner/inner.nom
@@ -1,3 +1,3 @@
-#!/usr/bin/env nomsu -V1
+#!/usr/bin/env nomsu -V2.4.4.3
 use "core"
-say "Inner directory 'use' test passed."
+say "Inner directory 'use' test passed."
\ No newline at end of file
diff --git a/tests/math.nom b/tests/math.nom
index 7ddefba..f740315 100644
--- a/tests/math.nom
+++ b/tests/math.nom
@@ -1,4 +1,4 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 #..
     Tests for the stuff defined in core/control_flow.nom
 use "core"
diff --git a/tests/metaprogramming.nom b/tests/metaprogramming.nom
index d74542c..b8dfde0 100644
--- a/tests/metaprogramming.nom
+++ b/tests/metaprogramming.nom
@@ -1,4 +1,4 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 #
     Tests for the stuff defined in core/metaprogramming.nom
 
@@ -68,4 +68,4 @@ lua> %code
 assume (=lua "global_x") or barf "Running lua from a variable failed."
 %code = (Lua value "global_x")
 assume (=lua %code) or barf "Running lua from a variable failed."
-say "Metaprogramming test passed."
+say "Metaprogramming test passed."
\ No newline at end of file
diff --git a/tests/object.nom b/tests/object.nom
index 30cf748..186957d 100644
--- a/tests/object.nom
+++ b/tests/object.nom
@@ -1,4 +1,4 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 #
     Tests for the object model defined in lib/object.nom
 
diff --git a/tests/operators.nom b/tests/operators.nom
index 0ab44c1..a8f7bfd 100644
--- a/tests/operators.nom
+++ b/tests/operators.nom
@@ -1,4 +1,4 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 #..
     Tests for the stuff defined in core/operators.nom
 use "core"
@@ -69,4 +69,4 @@ assume (%x == 2) or barf "+<- failed"
 assume (%x == 4) or barf "*<- failed"
 wrap %x around 3
 assume (%x == 1) or barf "wrap around failed"
-say "Operator test passed."
+say "Operator test passed."
\ No newline at end of file
diff --git a/tests/os.nom b/tests/os.nom
index cbda5b3..c96306b 100644
--- a/tests/os.nom
+++ b/tests/os.nom
@@ -1,4 +1,4 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 #
     Tests for the stuff defined in lib/os.nom
 
diff --git a/tests/scopes.nom b/tests/scopes.nom
index a882dcb..4d20dd7 100644
--- a/tests/scopes.nom
+++ b/tests/scopes.nom
@@ -1,4 +1,4 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 use "core"
 %x = "outer"
 with local %x:
diff --git a/tests/text.nom b/tests/text.nom
index 316b343..a002445 100644
--- a/tests/text.nom
+++ b/tests/text.nom
@@ -1,4 +1,4 @@
-#!/usr/bin/env nomsu -V2.3.4.3
+#!/usr/bin/env nomsu -V2.4.4.3
 #..
     Tests for the stuff defined in core/text.nom
 use "core"
@@ -40,10 +40,9 @@ assume (..)
     ..== "one\ntwo"
 
 assume ("nogap" == "nogap")
+
 #comment
 #
     block comment
 
-
-
 say "Text test passed."
\ No newline at end of file
diff --git a/tools/upgrade.nom b/tools/upgrade.nom
index 14f7ee0..8f478ac 100644
--- a/tools/upgrade.nom
+++ b/tools/upgrade.nom
@@ -1,4 +1,4 @@
-#!/usr/bin/env Nomsu -V2.3.4.3
+#!/usr/bin/env Nomsu -V2.4.4.3
 use "core"
 use "compatibility"
 use "lib/os.nom"
@@ -8,14 +8,25 @@ use "lib/os.nom"
 if (%args.1 is "-i"):
     %inplace = (yes)
     remove index 1 from %args
+if (%args.1 is "-t"):
+    use "lib/consolecolor.nom"
+    %test = (yes)
+    remove index 1 from %args
 for %path in %args:
     if (%path is "-i"): %inplace = (yes)
     for file %filename in %path:
         %tree = (parse (read file %filename) from %filename)
-        %tree = (%tree upgraded from %tree.version to (Nomsu version))
-        %text = "#!/usr/bin/env nomsu -V\(Nomsu version)\n\(%tree as nomsu)"
-        if %inplace:
-            write %text to file %filename
-        ..else:
-            say %text
+        %uptree = (%tree upgraded from %tree.version to (Nomsu version))
+        %text = "#!/usr/bin/env nomsu -V\(Nomsu version)\n\(%uptree as nomsu)"
+        if:
+            %inplace:
+                say "Upgraded \%filename"
+                write %text to file %filename
+            %test:
+                if (%uptree == %tree):
+                    say (dim "\%filename will not be changed")
+                ..else:
+                    say (bright "\%filename will be changed")
+            else:
+                say %text