diff --git a/compile.c b/compile.c
index 2255783..7c4913d 100644
--- a/compile.c
+++ b/compile.c
@@ -74,7 +74,7 @@ static bool promote(env_t *env, ast_t *ast, CORD *code, type_t *actual, type_t *
     if (needed->tag == NumType && actual->tag == OptionalType && Match(actual, OptionalType)->type->tag == NumType) {
         *code = CORD_all("({ ", compile_declaration(actual, "opt"), " = ", *code, "; ",
                          "if unlikely (", check_none(actual, "opt"), ")\n",
-                        CORD_asprintf("fail_source(%r, %ld, %ld, \"This was expected to be a value, but it's NONE\");\n",
+                        CORD_asprintf("fail_source(%r, %ld, %ld, \"This was expected to be a value, but it's none\");\n",
                                       CORD_quoted(ast->file->filename),
                                       (long)(ast->start - ast->file->text),
                                       (long)(ast->end - ast->file->text)),
@@ -470,7 +470,7 @@ static CORD compile_condition(env_t *env, ast_t *ast)
     } else if (t->tag == OptionalType) {
         return CORD_all("!", check_none(t, compile(env, ast)));
     } else if (t->tag == PointerType) {
-        code_err(ast, "This pointer will always be non-NONE, so it should not be used in a conditional.");
+        code_err(ast, "This pointer will always be non-none, so it should not be used in a conditional.");
     } else {
         code_err(ast, "%T values cannot be used for conditionals", t);
     }
@@ -1991,7 +1991,7 @@ CORD compile_none(type_t *t)
         env_t *enum_env = Match(t, EnumType)->env;
         return CORD_all("((", compile_type(t), "){", namespace_prefix(enum_env, enum_env->namespace), "null})");
     }
-    default: compiler_err(NULL, NULL, NULL, "NONE isn't implemented for this type: %T", t);
+    default: compiler_err(NULL, NULL, NULL, "none isn't implemented for this type: %T", t);
     }
 }
 
@@ -2033,7 +2033,7 @@ CORD compile(env_t *env, ast_t *ast)
     switch (ast->tag) {
     case None: {
         if (!Match(ast, None)->type)
-            code_err(ast, "This 'NONE' needs to specify what type it is using `NONE:Type` syntax");
+            code_err(ast, "This 'none' needs to specify what type it is using `none:Type` syntax");
         type_t *t = parse_type_ast(env, Match(ast, None)->type);
         return compile_none(t);
     }
@@ -2122,7 +2122,7 @@ CORD compile(env_t *env, ast_t *ast)
         CORD value_code = compile(env, value);
         return CORD_all("({ ", compile_declaration(t, "opt"), " = ", value_code, "; ",
                         "if unlikely (", check_none(t, "opt"), ")\n",
-                        CORD_asprintf("fail_source(%r, %ld, %ld, \"This was expected to be a value, but it's NONE\");\n",
+                        CORD_asprintf("fail_source(%r, %ld, %ld, \"This was expected to be a value, but it's none\");\n",
                                       CORD_quoted(ast->file->filename),
                                       (long)(value->start - value->file->text),
                                       (long)(value->end - value->file->text)),
diff --git a/docs/arrays.md b/docs/arrays.md
index c1886d4..efb108b 100644
--- a/docs/arrays.md
+++ b/docs/arrays.md
@@ -366,7 +366,7 @@ The index of the first occurrence or `!Int` if not found.
 = 2 : Int?
 
 >> [10, 20, 30, 40, 50]:find(9999)
-= NONE : Int?
+= none : Int?
 ```
 
 ---
@@ -396,7 +396,7 @@ item matches.
 >> [4, 5, 6]:find(func(i:&Int): i:is_prime())
 = 5 : Int?
 >> [4, 6, 8]:find(func(i:&Int): i:is_prime())
-= NONE : Int?
+= none : Int?
 ```
 
 ---
diff --git a/docs/booleans.md b/docs/booleans.md
index d2a22d5..ab6be43 100644
--- a/docs/booleans.md
+++ b/docs/booleans.md
@@ -33,5 +33,5 @@ func parse(text: Text -> Bool?)
 >> Bool.parse("no")
 = no : Bool?
 >> Bool.parse("???")
-= NONE : Bool?
+= none : Bool?
 ```
diff --git a/docs/integers.md b/docs/integers.md
index c832949..fe1fbc0 100644
--- a/docs/integers.md
+++ b/docs/integers.md
@@ -220,7 +220,7 @@ func parse(text: Text -> Int?)
 **Returns:**  
 The integer represented by the text. If the given text contains a value outside
 of the representable range or if the entire text can't be parsed as an integer,
-`NONE` will be returned.
+`none` will be returned.
 
 **Example:**  
 ```tomo
@@ -231,11 +231,11 @@ of the representable range or if the entire text can't be parsed as an integer,
 
 # Can't parse:
 >> Int.parse("asdf")
-= NONE : Int?
+= none : Int?
 
 # Outside valid range:
 >> Int8.parse("9999999")
-= NONE : Int8?
+= none : Int8?
 ```
 
 ---
diff --git a/docs/iterators.md b/docs/iterators.md
index 064af9c..ff7ed13 100644
--- a/docs/iterators.md
+++ b/docs/iterators.md
@@ -22,7 +22,7 @@ successively gets one line from a file at a time until the file is exhausted:
 >> iter()
 = "line three" : Text?
 >> iter()
-= NONE : Text?
+= none : Text?
 
 for line in (./test.txt):each_line():
     pass
diff --git a/docs/metamethods.md b/docs/metamethods.md
index a3f73b5..0983aff 100644
--- a/docs/metamethods.md
+++ b/docs/metamethods.md
@@ -6,7 +6,7 @@ behavior that is required for all types:
 - `func as_text(obj:&T?, colorize=no, type:&TypeInfo_t -> Text)`: a method to
   convert the type to a string. If `colorize` is `yes`, then the method should
   include ANSI escape codes for syntax highlighting. If the `obj` pointer is
-  `NONE`, a string representation of the type will be returned instead.
+  `none`, a string representation of the type will be returned instead.
 
 - `func compare(x:&T, y:&T, type:&TypeInfo_t -> Int32)`: Return an integer representing
   the result of comparing `x` and `y`, where negative numbers mean `x` is less
diff --git a/docs/moments.md b/docs/moments.md
index 84b71d0..1cd26ed 100644
--- a/docs/moments.md
+++ b/docs/moments.md
@@ -523,7 +523,7 @@ Returns a `Moment` object representing the current date and time.
 
 **Description:**  
 Return a new `Moment` object parsed from the given string in the given format,
-or `NONE` if the value could not be successfully parsed.
+or `none` if the value could not be successfully parsed.
 
 **Signature:**  
 ```tomo
@@ -539,7 +539,7 @@ func parse(text: Text, format: Text = "%Y-%m-%dT%H:%M:%S%z" -> Moment?)
 
 **Returns:**
 If the text was successfully parsed according to the given format, return a
-`Moment` representing that information. Otherwise, return `NONE`.
+`Moment` representing that information. Otherwise, return `none`.
 
 **Example:**  
 ```tomo
diff --git a/docs/nums.md b/docs/nums.md
index 4a6b06d..b8d7459 100644
--- a/docs/nums.md
+++ b/docs/nums.md
@@ -26,7 +26,7 @@ differentiate between possibly-NaN values and definitely-not-NaN values.
 
 Tomo has a separate concept for expressing the lack of a defined value:
 optional types. Consequently, Tomo has merged these two concepts, so `NaN` is
-called `NONE` and has the type `Num?` or `Num32?`. In this way, it's no
+called `none` and has the type `Num?` or `Num32?`. In this way, it's no
 different from optional integers or optional arrays. This means that if a
 variable has type `Num`, it is guaranteed to not hold a NaN value. This also
 means that operations which may produce NaN values have a result type of
@@ -36,9 +36,9 @@ values (zero times infinity), and many math functions like `sqrt()` can return
 NaN for some inputs.
 
 Unfortunately, one of the big downsides of optional types is that explicit
-`NONE` handling can be very verbose. To make Nums actually usable, Tomo applies
-very liberal use of type coercion and implicit `NONE` checks when values are
-required to be non-NONE. Here are a few examples:
+`none` handling can be very verbose. To make Nums actually usable, Tomo applies
+very liberal use of type coercion and implicit `none` checks when values are
+required to be non-none. Here are a few examples:
 
 ```tomo
 >> x := 0.0
@@ -46,17 +46,17 @@ required to be non-NONE. Here are a few examples:
 
 y := 1.0
 
-# Division might produce NONE:
+# Division might produce none:
 >> x / y
 = 0 : Num?
 >> x / x
-= NONE : Num?
+= none : Num?
 
-# Optional types and NONE values propagate:
+# Optional types and none values propagate:
 >> x/y + 1 + 2
 = 3 : Num?
 >> x/x + 1 + 2
-= NONE : Num?
+= none : Num?
 
 # Optional Nums can be handled explicitly using `or` and `!`:
 >> x/x or -123
@@ -66,18 +66,18 @@ y := 1.0
 >> (x/y)!
 = 0 : Num
 
-# Assigning to a non-optional variable will do an implicit check for NONE and
-# raise a runtime error if the value is NONE, essentially the same as an
+# Assigning to a non-optional variable will do an implicit check for none and
+# raise a runtime error if the value is none, essentially the same as an
 # implicit `!`:
 x = x/y
 
 func doop(x:Num -> Num):
     # If a function's return type is non-optional and an optional value is
-    # used in a return statement, an implicit NONE check will be inserted and
-    # will error if the value is NONE:
+    # used in a return statement, an implicit none check will be inserted and
+    # will error if the value is none:
     return x / 2
 
-# Function arguments are also implicitly checked for NONE if the given value
+# Function arguments are also implicitly checked for none if the given value
 # is optional and the function needs a non-optional value:
 >> doop(x/y)
 = 0 : Num
@@ -665,7 +665,7 @@ func parse(text: Text -> Num?)
 - `text`: The text containing the number.
 
 **Returns:**
-The number represented by the text or `NONE` if the entire text can't be parsed
+The number represented by the text or `none` if the entire text can't be parsed
 as a number.
 
 **Example:**
diff --git a/docs/optionals.md b/docs/optionals.md
index a0f5462..56b7ba1 100644
--- a/docs/optionals.md
+++ b/docs/optionals.md
@@ -35,12 +35,12 @@ Optional types are written using a `?` after the type name. So, an optional
 integer would be written as `Int?` and an optional array of texts would be
 written as `[Text]?`.
 
-None can be written explicitly using `NONE` with a type annotation. For
+None can be written explicitly using `none` with a type annotation. For
 example, if you wanted to declare a variable that could be either an integer
-value or `NONE` and initialize it as none, you would write it as:
+value or `none` and initialize it as none, you would write it as:
 
 ```tomo
-x := NONE:Int
+x := none:Int
 ```
 
 Similarly, if you wanted to declare a variable that could be an array of texts
@@ -51,7 +51,7 @@ x := ![Text]
 ```
 
 If you want to declare a variable and initialize it with a non-none value, but
-keep open the possibility of assigning `NONE` later, you can use the postfix
+keep open the possibility of assigning `none` later, you can use the postfix
 `?` operator to indicate that a value is optional:
 
 ```tomo
@@ -62,7 +62,7 @@ x = !Int
 
 ## Type Inference
 
-For convenience, `NONE` can also be written without the explicit type
+For convenience, `none` can also be written without the explicit type
 annotation for any type in situations where the compiler knows what type of
 optional value is expected:
 
@@ -74,12 +74,12 @@ Here are some examples:
 
 ```tomo
 x := 5?
-x = NONE
+x = none
 
 func doop(arg:Int?)->Text?:
-    return NONE
+    return none
 
-doop(NONE)
+doop(none)
 ```
 
 Non-none values can also be automatically promoted to optional values without
@@ -97,7 +97,7 @@ doop(123)
 
 ## None Checking
 
-In addition to using conditionals to check for `NONE`, you can also use `or` to
+In addition to using conditionals to check for `none`, you can also use `or` to
 get a non-none value by either providing an alternative non-none value or by
 providing an early out statement like `return`/`skip`/`stop` or a function with
 an `Abort` type like `fail()` or `exit()`:
diff --git a/docs/paths.md b/docs/paths.md
index f2b4452..b6d62b6 100644
--- a/docs/paths.md
+++ b/docs/paths.md
@@ -495,7 +495,7 @@ raised.
 = "Hello" : Text?
 
 >> (./nosuchfile.xxx):read()
-= NONE : Text?
+= none : Text?
 ```
 ---
 
@@ -524,7 +524,7 @@ returned.
 = [72[B], 101[B], 108[B], 108[B], 111[B]] : [Byte]?
 
 >> (./nosuchfile.xxx):read()
-= NONE : [Byte]?
+= none : [Byte]?
 ```
 
 ---
diff --git a/docs/reductions.md b/docs/reductions.md
index d68b388..58cfa31 100644
--- a/docs/reductions.md
+++ b/docs/reductions.md
@@ -22,7 +22,7 @@ nums := [:Int]
 sum := (+: nums)
 
 >> sum
-= NONE : Int?
+= none : Int?
 
 >> sum or 0
 = 0
diff --git a/docs/serialization.md b/docs/serialization.md
index ea21f90..764a6b2 100644
--- a/docs/serialization.md
+++ b/docs/serialization.md
@@ -52,7 +52,7 @@ cyclic datastructures correctly, enabling you to serialize cyclic structures
 like circularly linked lists or graphs:
 
 ```tomo
-struct Cycle(name:Text, next=NONE:@Cycle)
+struct Cycle(name:Text, next=none:@Cycle)
 
 c := @Cycle("A")
 c.next = @Cycle("B", next=c)
diff --git a/docs/tables.md b/docs/tables.md
index ef2333a..a8a2793 100644
--- a/docs/tables.md
+++ b/docs/tables.md
@@ -43,12 +43,12 @@ table := {"A": 1, "B": 2}
 >> table["A"]
 = 1 : Int?
 >> table["missing"]
-= NONE : Int?
+= none : Int?
 ```
 
 As with all optional values, you can use the `!` postfix operator to assert
-that the value is non-NONE (and create a runtime error if it is), or you can
-use the `or` operator to provide a fallback value in the case that it's NONE:
+that the value is non-none (and create a runtime error if it is), or you can
+use the `or` operator to provide a fallback value in the case that it's none:
 
 ```tomo
 >> table["A"]!
@@ -77,7 +77,7 @@ table value:
 >> t2.fallback
 = {"A":10} : {Text:Int}?
 >> t.fallback
-= NONE : {Text:Int}?
+= none : {Text:Int}?
 ```
 
 ## Setting Values
@@ -213,7 +213,7 @@ The value associated with the key or null if the key is not found.
 = 1 : Int?
 
 >> t:get("????")
-= NONE : Int?
+= none : Int?
 
 >> t:get("A")!
 = 1 : Int
diff --git a/docs/text.md b/docs/text.md
index d67f0a7..463a233 100644
--- a/docs/text.md
+++ b/docs/text.md
@@ -695,9 +695,9 @@ containing information about the match.
 **Example:**  
 ```tomo
 >> " #one   #two  #three   ":find($/#{id}/, start=-999)
-= NONE : Match?
+= none : Match?
 >> " #one   #two  #three   ":find($/#{id}/, start=999)
-= NONE : Match?
+= none : Match?
 >> " #one   #two  #three   ":find($/#{id}/)
 = Match(text="#one", index=2, captures=["one"]) : Match?
 >> " #one   #two  #three   ":find("{id}", start=6)
@@ -887,7 +887,7 @@ or a null value otherwise.
 **Example:**  
 ```tomo
 >> "hello world":matches($/{id}/)
-= NONE : [Text]?
+= none : [Text]?
 
 >> "hello world":matches($/{id} {id}/)
 = ["hello", "world"] : [Text]?
diff --git a/environment.c b/environment.c
index b5edc20..6182143 100644
--- a/environment.c
+++ b/environment.c
@@ -293,29 +293,29 @@ env_t *new_compilation_unit(CORD libname)
             // Used as a default for functions below:
             {"now", "Moment$now", "func(->Moment)"},
 
-            {"after", "Moment$after", "func(moment:Moment,seconds,minutes,hours=0.0,days,weeks,months,years=0,timezone=NONE:Text -> Moment)"},
-            {"date", "Moment$date", "func(moment:Moment,timezone=NONE:Text -> Text)"},
-            {"day_of_month", "Moment$day_of_month", "func(moment:Moment,timezone=NONE:Text -> Int)"},
-            {"day_of_week", "Moment$day_of_week", "func(moment:Moment,timezone=NONE:Text -> Int)"},
-            {"day_of_year", "Moment$day_of_year", "func(moment:Moment,timezone=NONE:Text -> Int)"},
-            {"format", "Moment$format", "func(moment:Moment,format=\"%Y-%m-%dT%H:%M:%S%z\",timezone=NONE:Text -> Text)"},
+            {"after", "Moment$after", "func(moment:Moment,seconds,minutes,hours=0.0,days,weeks,months,years=0,timezone=none:Text -> Moment)"},
+            {"date", "Moment$date", "func(moment:Moment,timezone=none:Text -> Text)"},
+            {"day_of_month", "Moment$day_of_month", "func(moment:Moment,timezone=none:Text -> Int)"},
+            {"day_of_week", "Moment$day_of_week", "func(moment:Moment,timezone=none:Text -> Int)"},
+            {"day_of_year", "Moment$day_of_year", "func(moment:Moment,timezone=none:Text -> Int)"},
+            {"format", "Moment$format", "func(moment:Moment,format=\"%Y-%m-%dT%H:%M:%S%z\",timezone=none:Text -> Text)"},
             {"from_unix_timestamp", "Moment$from_unix_timestamp", "func(timestamp:Int64 -> Moment)"},
             {"get_local_timezone", "Moment$get_local_timezone", "func(->Text)"},
-            {"hour", "Moment$hour", "func(moment:Moment,timezone=NONE:Text -> Int)"},
+            {"hour", "Moment$hour", "func(moment:Moment,timezone=none:Text -> Int)"},
             {"hours_till", "Moment$hours_till", "func(now,then:Moment -> Num)"},
-            {"minute", "Moment$minute", "func(moment:Moment,timezone=NONE:Text -> Int)"},
+            {"minute", "Moment$minute", "func(moment:Moment,timezone=none:Text -> Int)"},
             {"minutes_till", "Moment$minutes_till", "func(now,then:Moment -> Num)"},
-            {"month", "Moment$month", "func(moment:Moment,timezone=NONE:Text -> Int)"},
-            {"microsecond", "Moment$microsecond", "func(moment:Moment,timezone=NONE:Text -> Int)"},
-            {"new", "Moment$new", "func(year,month,day:Int,hour,minute=0,second=0.0,timezone=NONE:Text -> Moment)"},
+            {"month", "Moment$month", "func(moment:Moment,timezone=none:Text -> Int)"},
+            {"microsecond", "Moment$microsecond", "func(moment:Moment,timezone=none:Text -> Int)"},
+            {"new", "Moment$new", "func(year,month,day:Int,hour,minute=0,second=0.0,timezone=none:Text -> Moment)"},
             {"parse", "Moment$parse", "func(text:Text, format=\"%Y-%m-%dT%H:%M:%S%z\" -> Moment?)"},
-            {"relative", "Moment$relative", "func(moment:Moment,relative_to=Moment.now(),timezone=NONE:Text -> Text)"},
-            {"second", "Moment$second", "func(moment:Moment,timezone=NONE:Text -> Int)"},
+            {"relative", "Moment$relative", "func(moment:Moment,relative_to=Moment.now(),timezone=none:Text -> Text)"},
+            {"second", "Moment$second", "func(moment:Moment,timezone=none:Text -> Int)"},
             {"seconds_till", "Moment$seconds_till", "func(now:Moment,then:Moment -> Num)"},
-            {"set_local_timezone", "Moment$set_local_timezone", "func(timezone=NONE:Text)"},
-            {"time", "Moment$time", "func(moment:Moment,seconds=no,am_pm=yes,timezone=NONE:Text -> Text)"},
+            {"set_local_timezone", "Moment$set_local_timezone", "func(timezone=none:Text)"},
+            {"time", "Moment$time", "func(moment:Moment,seconds=no,am_pm=yes,timezone=none:Text -> Text)"},
             {"unix_timestamp", "Moment$unix_timestamp", "func(moment:Moment -> Int64)"},
-            {"year", "Moment$year", "func(moment:Moment,timezone=NONE:Text -> Int)"},
+            {"year", "Moment$year", "func(moment:Moment,timezone=none:Text -> Int)"},
         )},
         {"Path", Type(TextType, .lang="Path", .env=namespace_env(env, "Path")), "Text_t", "Text$info", TypedArray(ns_entry_t,
             {"append", "Path$append", "func(path:Path, text:Text, permissions=Int32(0o644))"},
@@ -338,7 +338,7 @@ env_t *new_compilation_unit(CORD libname)
             {"is_symlink", "Path$is_symlink", "func(path:Path -> Bool)"},
             {"parent", "Path$parent", "func(path:Path -> Path)"},
             {"read", "Path$read", "func(path:Path -> Text?)"},
-            {"read_bytes", "Path$read_bytes", "func(path:Path, limit=NONE:Int -> [Byte]?)"},
+            {"read_bytes", "Path$read_bytes", "func(path:Path, limit=none:Int -> [Byte]?)"},
             {"relative", "Path$relative", "func(path:Path, relative_to=(./) -> Path)"},
             {"remove", "Path$remove", "func(path:Path, ignore_missing=no)"},
             {"resolved", "Path$resolved", "func(path:Path, relative_to=(./) -> Path)"},
diff --git a/examples/base64/base64.tm b/examples/base64/base64.tm
index bed94ac..52af6e8 100644
--- a/examples/base64/base64.tm
+++ b/examples/base64/base64.tm
@@ -59,10 +59,10 @@ lang Base64:
             output[dest+2] = _EQUAL_BYTE
             output[dest+3] = _EQUAL_BYTE
 
-        return Base64.without_escaping(Text.from_bytes(output) or return NONE)
+        return Base64.without_escaping(Text.from_bytes(output) or return none)
 
     func decode_text(b64:Base64 -> Text?):
-        return Text.from_bytes(b64:decode_bytes() or return NONE)
+        return Text.from_bytes(b64:decode_bytes() or return none)
 
     func decode_bytes(b64:Base64 -> [Byte]?):
         bytes := b64.text_content:bytes()
diff --git a/examples/http/http.tm b/examples/http/http.tm
index f36fac6..425a7ba 100644
--- a/examples/http/http.tm
+++ b/examples/http/http.tm
@@ -78,7 +78,7 @@ func _send(method:_Method, url:Text, data:Text?, headers=[:Text] -> HTTPResponse
     return HTTPResponse(Int(code), "":join(chunks))
 
 func get(url:Text, headers=[:Text] -> HTTPResponse):
-    return _send(GET, url, NONE, headers)
+    return _send(GET, url, none, headers)
 
 func post(url:Text, data="", headers=["Content-Type: application/json", "Accept: application/json"] -> HTTPResponse):
     return _send(POST, url, data, headers)
@@ -89,7 +89,7 @@ func put(url:Text, data="", headers=["Content-Type: application/json", "Accept:
 func patch(url:Text, data="", headers=["Content-Type: application/json", "Accept: application/json"] -> HTTPResponse):
     return _send(PATCH, url, data, headers)
 
-func delete(url:Text, data=NONE:Text, headers=["Content-Type: application/json", "Accept: application/json"] -> HTTPResponse):
+func delete(url:Text, data=none:Text, headers=["Content-Type: application/json", "Accept: application/json"] -> HTTPResponse):
     return _send(DELETE, url, data, headers)
 
 func main():
diff --git a/examples/learnxiny.tm b/examples/learnxiny.tm
index af7a55f..5315b03 100644
--- a/examples/learnxiny.tm
+++ b/examples/learnxiny.tm
@@ -108,17 +108,17 @@ func main():
     >> table["two"]
     = 2 : Int?
 
-    # The value returned is optional because NONE will be returned if the key
+    # The value returned is optional because none will be returned if the key
     # is not in the table:
     >> table["xxx"]!
-    = NONE : Int?
+    = none : Int?
 
     # Optional values can be converted to regular values using `!` (which will
     # create a runtime error if the value is null):
     >> table["two"]!
     = 2 : Int
 
-    # You can also use `or` to provide a fallback value to replace NONE:
+    # You can also use `or` to provide a fallback value to replace none:
     >> table["xxx"] or 0
     = 0 : Int
 
diff --git a/examples/threads/threads.tm b/examples/threads/threads.tm
index 8be568c..16beb9b 100644
--- a/examples/threads/threads.tm
+++ b/examples/threads/threads.tm
@@ -85,7 +85,7 @@ func main():
 
     t := PThread.new(func():
         say("In another thread!")
-        item := @NONE:Int
+        item := @none:Int
         while item[] != 30:
             g:guarded(func():
                 while queue.length == 0:
diff --git a/examples/tomo-install/tomo-install.tm b/examples/tomo-install/tomo-install.tm
index 998462d..f769204 100644
--- a/examples/tomo-install/tomo-install.tm
+++ b/examples/tomo-install/tomo-install.tm
@@ -38,7 +38,7 @@ func main(paths:[Path]):
             say("Already installed: $url")
             skip
 
-        alias := NONE:Text
+        alias := none:Text
         curl_flags := ["-L"]
         if github := url_without_protocol:matches($|github.com/{!/}/{!/}#{..}|):
             user := github[1]
diff --git a/parse.c b/parse.c
index 17ebcea..1cd51bd 100644
--- a/parse.c
+++ b/parse.c
@@ -53,7 +53,7 @@ int op_tightness[] = {
 static const char *keywords[] = {
     "yes", "xor", "while", "when", "use", "unless", "struct", "stop", "skip", "return",
     "or", "not", "no", "mod1", "mod", "pass", "lang", "inline", "in", "if",
-    "func", "for", "extern", "enum", "else", "do", "deserialize", "defer", "and", "NONE",
+    "func", "for", "extern", "enum", "else", "do", "deserialize", "defer", "and", "none",
     "_min_", "_max_", NULL,
 };
 
@@ -1545,7 +1545,7 @@ PARSER(parse_lambda) {
 
 PARSER(parse_none) {
     const char *start = pos;
-    if (!match_word(&pos, "NONE"))
+    if (!match_word(&pos, "none"))
         return NULL;
 
     const char *none_end = pos;
diff --git a/stdlib/optionals.c b/stdlib/optionals.c
index 38cd470..ccda980 100644
--- a/stdlib/optionals.c
+++ b/stdlib/optionals.c
@@ -53,7 +53,7 @@ public Text_t Optional$as_text(const void *obj, bool colorize, const TypeInfo_t
         return Text$concat(generic_as_text(obj, colorize, type->OptionalInfo.type), Text("?"));
 
     if (is_none(obj, type->OptionalInfo.type))
-        return colorize ? Text("\x1b[31mNONE\x1b[m") : Text("NONE");
+        return colorize ? Text("\x1b[31mnone\x1b[m") : Text("none");
     return generic_as_text(obj, colorize, type->OptionalInfo.type);
 }
 
diff --git a/test/arrays.tm b/test/arrays.tm
index 0d21ea1..f59ed6c 100644
--- a/test/arrays.tm
+++ b/test/arrays.tm
@@ -162,9 +162,9 @@ func main():
 	>> ["a", "b", "c"]:find("b")
 	= 2 : Int?
 	>> ["a", "b", "c"]:find("XXX")
-	= NONE : Int?
+	= none : Int?
 
 	>> [10, 20]:first(func(i:&Int): i:is_prime())
-	= NONE : Int?
+	= none : Int?
 	>> [4, 5, 6]:first(func(i:&Int): i:is_prime())
 	= 2 : Int?
diff --git a/test/iterators.tm b/test/iterators.tm
index ebb040f..4a85e6f 100644
--- a/test/iterators.tm
+++ b/test/iterators.tm
@@ -4,7 +4,7 @@ struct Pair(x:Text, y:Text)
 func pairwise(strs:[Text] -> func(->Pair?)):
     i := 1
     return func():
-        if i + 1 > strs.length: return NONE:Pair
+        if i + 1 > strs.length: return none:Pair
         i += 1
         return Pair(strs[i-1], strs[i])?
 
@@ -12,7 +12,7 @@ func range(first:Int, last:Int -> func(->Int?)):
     i := first
     return func():
         if i > last:
-            return NONE:Int
+            return none:Int
         i += 1
         return (i-1)?
 
diff --git a/test/nums.tm b/test/nums.tm
index 3a66ffe..1192826 100644
--- a/test/nums.tm
+++ b/test/nums.tm
@@ -22,8 +22,8 @@ func main():
 	>> Num.INF:isinf()
 	= yes
 
-	>> nan := NONE : Num
-	= NONE : Num?
+	>> nan := none : Num
+	= none : Num?
 	>> nan == nan
 	= yes
 	>> nan < nan
@@ -46,10 +46,10 @@ func main():
 	= -1
 
 	>> nan + 1
-	= NONE : Num?
+	= none : Num?
 
 	>> 0./0.
-	= NONE : Num?
+	= none : Num?
 
 	>> Num.PI:cos()!:near(-1)
 	= yes
diff --git a/test/optionals.tm b/test/optionals.tm
index acefdd2..2ccdf39 100644
--- a/test/optionals.tm
+++ b/test/optionals.tm
@@ -4,81 +4,81 @@ struct Struct(x:Int, y:Text):
         if should_i:
             return Struct(123, "hello")
         else:
-            return NONE
+            return none
 
 enum Enum(X, Y(y:Int)):
     func maybe(should_i:Bool->Enum?):
         if should_i:
             return Enum.Y(123)
         else:
-            return NONE
+            return none
 
 func maybe_int(should_i:Bool->Int?):
     if should_i:
         return 123
     else:
-        return NONE
+        return none
 
 func maybe_int64(should_i:Bool->Int64?):
     if should_i:
         return Int64(123)
     else:
-        return NONE
+        return none
 
 func maybe_array(should_i:Bool->[Int]?):
     if should_i:
         return [10, 20, 30]
     else:
-        return NONE
+        return none
 
 func maybe_bool(should_i:Bool->Bool?):
     if should_i:
         return no
     else:
-        return NONE
+        return none
 
 func maybe_text(should_i:Bool->Text?):
     if should_i:
         return "Hello"
     else:
-        return NONE
+        return none
 
 func maybe_num(should_i:Bool->Num?):
     if should_i:
         return 12.3
     else:
-        return NONE
+        return none
 
 func maybe_lambda(should_i:Bool-> func()?):
     if should_i:
         return func(): say("hi!")
     else:
-        return NONE
+        return none
 
 func maybe_c_string(should_i:Bool->CString?):
     if should_i:
         return ("hi":as_c_string())?
     else:
-        return NONE
+        return none
 
 func maybe_channel(should_i:Bool->|Int|?):
     if should_i:
         return |:Int|?
     else:
-        return NONE
+        return none
 
 func maybe_thread(should_i:Bool->Thread?):
     if should_i:
         return Thread.new(func(): pass)
     else:
-        return NONE
+        return none
 
 func main():
     >> 5?
     = 5 : Int?
 
     >> if no:
-        NONE:Int
+        none:Int
     else:
         5
     = 5 : Int?
@@ -92,7 +92,7 @@ func main():
     >> 5? or exit("Non-null is falsey")
     = 5 : Int
 
-    >> (NONE:Int) or -1
+    >> (none:Int) or -1
     = -1 : Int
 
     do:
@@ -100,7 +100,7 @@ func main():
         >> yep := maybe_int(yes)
         = 123 : Int?
         >> nope := maybe_int(no)
-        = NONE : Int?
+        = none : Int?
         >> if yep:
             >> yep
             = 123
@@ -115,7 +115,7 @@ func main():
         >> yep := maybe_int64(yes)
         = 123 : Int64?
         >> nope := maybe_int64(no)
-        = NONE : Int64?
+        = none : Int64?
         >> if yep:
             >> yep
             = 123
@@ -130,7 +130,7 @@ func main():
         >> yep := maybe_array(yes)
         = [10, 20, 30] : [Int]?
         >> nope := maybe_array(no)
-        = NONE : [Int]?
+        = none : [Int]?
         >> if yep:
             >> yep
             = [10, 20, 30]
@@ -145,7 +145,7 @@ func main():
         >> yep := maybe_bool(yes)
         = no : Bool?
         >> nope := maybe_bool(no)
-        = NONE : Bool?
+        = none : Bool?
         >> if yep:
             >> yep
             = no
@@ -160,7 +160,7 @@ func main():
         >> yep := maybe_text(yes)
         = "Hello" : Text?
         >> nope := maybe_text(no)
-        = NONE : Text?
+        = none : Text?
         >> if yep:
             >> yep
             = "Hello"
@@ -175,7 +175,7 @@ func main():
         >> yep := maybe_num(yes)
         = 12.3 : Num?
         >> nope := maybe_num(no)
-        = NONE : Num?
+        = none : Num?
         >> if yep:
             >> yep
             = 12.3
@@ -190,7 +190,7 @@ func main():
         >> yep := maybe_lambda(yes)
         = func() [optionals.tm:54] : func()?
         >> nope := maybe_lambda(no)
-        = NONE : func()?
+        = none : func()?
         >> if yep:
             >> yep
             = func() [optionals.tm:54]
@@ -205,7 +205,7 @@ func main():
         >> yep := Struct.maybe(yes)
         = Struct(x=123, y="hello") : Struct?
         >> nope := Struct.maybe(no)
-        = NONE : Struct?
+        = none : Struct?
         >> if yep:
             >> yep
             = Struct(x=123, y="hello")
@@ -220,7 +220,7 @@ func main():
         >> yep := Enum.maybe(yes)
         = Enum.Y(123) : Enum?
         >> nope := Enum.maybe(no)
-        = NONE : Enum?
+        = none : Enum?
         >> if yep:
             >> yep
             = Enum.Y(123)
@@ -235,7 +235,7 @@ func main():
         >> yep := maybe_c_string(yes)
         = CString("hi") : CString?
         >> nope := maybe_c_string(no)
-        = NONE : CString?
+        = none : CString?
         >> if yep:
             >> yep
             = CString("hi")
@@ -250,7 +250,7 @@ func main():
         >> yep := maybe_channel(yes)
         # No "=" test here because channels use addresses in the text version
         >> nope := maybe_channel(no)
-        = NONE : |:Int|?
+        = none : |:Int|?
         >> if yep: >> yep
         else: fail("Falsey: $yep")
         >> if nope:
@@ -263,7 +263,7 @@ func main():
         >> yep := maybe_thread(yes)
         # No "=" test here because threads use addresses in the text version
         >> nope := maybe_thread(no)
-        = NONE : Thread?
+        = none : Thread?
         >> if yep: >> yep
         else: fail("Falsey: $yep")
         >> if nope:
@@ -279,14 +279,16 @@ func main():
     = 123 : Int
 
     # Test comparisons, hashing, equality:
-    >> (NONE:Int == 5?)
+    >> (none:Int == 5?)
     = no
     >> (5? == 5?)
     = yes
-    >> {NONE:Int, NONE:Int}
-    = {NONE}
-    >> [5?, NONE:Int, NONE:Int, 6?]:sorted()
-    = [NONE, NONE, 5, 6]
+    >> {none:Int, none:Int}
+    = {none}
+    >> {:Int? none, none}
+    = {none}
+    >> [5?, none:Int, none:Int, 6?]:sorted()
+    = [none, none, 5, 6]
 
     do:
         >> value := if var := 5?:
@@ -296,7 +298,7 @@ func main():
         = 5
 
     do:
-        >> value := if var := NONE:Int:
+        >> value := if var := none:Int:
             var
         else:
             0
@@ -310,7 +312,7 @@ func main():
             >> opt
 
     do:
-        >> opt := NONE:Int
+        >> opt := none:Int
         >> if opt:
             >> opt
         else:
@@ -319,7 +321,7 @@ func main():
     >> not 5?
     = no
 
-    >> not NONE:Int
+    >> not none:Int
     = yes
 
     >> [Struct(5,"A")?, Struct(6,"B"), Struct(7,"C")]
diff --git a/test/paths.tm b/test/paths.tm
index 25cb4e5..1a8da4c 100644
--- a/test/paths.tm
+++ b/test/paths.tm
@@ -36,9 +36,9 @@ func main():
         fail("Couldn't read lines in $tmpfile")
 
     >> (./does-not-exist.xxx):read()
-    = NONE : Text?
+    = none : Text?
     >> (./does-not-exist.xxx):read_bytes()
-    = NONE : [Byte]?
+    = none : [Byte]?
     if lines := (./does-not-exist.xxx):by_line():
         fail("I could read lines in a nonexistent file")
     else:
diff --git a/test/reductions.tm b/test/reductions.tm
index 26f3533..7ab9577 100644
--- a/test/reductions.tm
+++ b/test/reductions.tm
@@ -5,7 +5,7 @@ func main():
 	= 60 : Int?
 
 	>> (+: [:Int])
-	= NONE : Int?
+	= none : Int?
 
 	>> (+: [10, 20, 30]) or 0
 	= 60
@@ -37,7 +37,7 @@ func main():
 	= yes
 
 	>> (<=: [:Int])
-	= NONE : Bool?
+	= none : Bool?
 
 	>> (<=: [5, 4, 3, 2, 1])!
 	= no
diff --git a/test/serialization.tm b/test/serialization.tm
index da79f1b..a442d9e 100644
--- a/test/serialization.tm
+++ b/test/serialization.tm
@@ -1,5 +1,5 @@
 
-struct Foo(name:Text, next=NONE:@Foo)
+struct Foo(name:Text, next=none:@Foo)
 
 enum MyEnum(Zero, One(x:Int), Two(x:Num, y:Text))
 
@@ -88,7 +88,7 @@ func main():
         = yes
 
     do:
-        >> obj := NONE:Num
+        >> obj := none:Num
         >> bytes := obj:serialized()
         >> deserialize(bytes -> Num?) == obj
         = yes
diff --git a/test/structs.tm b/test/structs.tm
index afbb1a8..de220b1 100644
--- a/test/structs.tm
+++ b/test/structs.tm
@@ -2,11 +2,11 @@
 struct Single(x:Int)
 struct Pair(x,y:Int)
 struct Mixed(x:Int, text:Text)
-struct LinkedList(x:Int, next=NONE:@LinkedList)
+struct LinkedList(x:Int, next=none:@LinkedList)
 struct Password(text:Text; secret)
 
 struct CorecursiveA(other:@CorecursiveB?)
-struct CorecursiveB(other=NONE:@CorecursiveA)
+struct CorecursiveB(other=none:@CorecursiveA)
 
 func test_literals():
 	>> Single(123)
diff --git a/test/tables.tm b/test/tables.tm
index 0d8954a..403f25e 100644
--- a/test/tables.tm
+++ b/test/tables.tm
@@ -7,7 +7,7 @@ func main():
 	>> t["two"]
 	= 2 : Int?
 	>> t["???"]
-	= NONE : Int?
+	= none : Int?
 	>> t["one"]!
 	= 1
 	>> t["???"] or -1
@@ -22,7 +22,7 @@ func main():
 	>> t.length
 	= 2
 	>> t.fallback
-	= NONE : {Text:Int}?
+	= none : {Text:Int}?
 
 	>> t.keys
 	= ["one", "two"]
@@ -37,7 +37,7 @@ func main():
 	>> t2["three"]
 	= 3 : Int?
 	>> t2["???"]
-	= NONE : Int?
+	= none : Int?
 
 	>> t2.length
 	= 1
diff --git a/test/text.tm b/test/text.tm
index c6fb6ad..26fd4c6 100644
--- a/test/text.tm
+++ b/test/text.tm
@@ -35,7 +35,7 @@ func main():
 	>> Text.from_bytes([:Byte 0x41, 0x6D, 0xC3, 0xA9, 0x6C, 0x69, 0x65])!
 	= "Amélie"
 	>> Text.from_bytes([Byte(0xFF)])
-	= NONE : Text?
+	= none : Text?
 
 	>> amelie2 := "Am$(\U65\U301)lie"
 	>> amelie2:split()
@@ -189,9 +189,9 @@ func main():
 
 	!! Test text:find()
 	>> " one   two  three   ":find($/{id}/, start=-999)
-	= NONE : Match?
+	= none : Match?
 	>> " one   two  three   ":find($/{id}/, start=999)
-	= NONE : Match?
+	= none : Match?
 	>> " one   two  three   ":find($/{id}/)
 	= Match(text="one", index=2, captures=["one"]) : Match?
 	>> " one   two  three   ":find($/{id}/, start=5)
@@ -222,7 +222,7 @@ func main():
 	= ["PENGUIN"]
 
 	>> Text.from_codepoint_names(["not a valid name here buddy"])
-	= NONE : Text?
+	= none : Text?
 
 	>> "one two; three four":find_all($/; {..}/)
 	= [Match(text="; three four", index=8, captures=["three four"])]
@@ -249,11 +249,11 @@ func main():
 	>> "Hello":matches($/{id}/)
 	= ["Hello"] : [Text]?
 	>> "Hello":matches($/{lower}/)
-	= NONE : [Text]?
+	= none : [Text]?
 	>> "Hello":matches($/{upper}/)
-	= NONE : [Text]?
+	= none : [Text]?
 	>> "Hello...":matches($/{id}/)
-	= NONE : [Text]?
+	= none : [Text]?
 
 	if matches := "hello world":matches($/{id} {id}/):
 		>> matches
diff --git a/typecheck.c b/typecheck.c
index 64660f0..4cdc683 100644
--- a/typecheck.c
+++ b/typecheck.c
@@ -520,7 +520,7 @@ type_t *get_type(env_t *env, ast_t *ast)
             return Type(OptionalType, .type=NULL);
         type_t *t = parse_type_ast(env, Match(ast, None)->type);
         if (t->tag == OptionalType)
-            code_err(ast, "Nested optional types are not supported. This should be: `NONE:%T`", Match(t, OptionalType)->type);
+            code_err(ast, "Nested optional types are not supported. This should be: `none:%T`", Match(t, OptionalType)->type);
         return Type(OptionalType, .type=t);
     }
     case Bool: {