diff --git a/sallyforth/basic_words.py b/sallyforth/basic_words.py
index 926a813..50f670c 100644
--- a/sallyforth/basic_words.py
+++ b/sallyforth/basic_words.py
@@ -3,6 +3,7 @@ import importlib
 import os
 from compiler import Compiler
 from arglist import Arglist
+from operator_words import w_not
 
 def const_f(value):
     def x(f, i):
@@ -25,11 +26,15 @@ def native_function_handler(func):
 def import_native_module(forth, m, alias=None, excludes=[]):
     if not alias:
         alias = m.__name__
+    alias = alias.replace(".", "/")
+    print(m, alias)
+
     raw_names = dir(m)
     names = [x for x in raw_names if x not in excludes] 
     for name in names:
-        localname = f'{alias}.{name}'
+        localname = f'{alias}/{name}'
         val = getattr(m, name)
+        print("setting", localname)
         forth.namespace.set(localname, const_f(val))
 
 def w_eval(f, i):
@@ -62,10 +67,18 @@ def w_ns(f, i):
         f.namespace = new_ns
     return i + 1
 
+def w_resolve(f, i):
+    token = f.stack.pop()
+    print("token", token)
+    resolved = f.resolve_token(token)
+    print("resovled:", resolved)
+    f.stack.push(resolved)
+    return i + 1
+
 def w_alias(f, i):
     new_name = f.stack.pop() 
     old_name = f.stack.pop() 
-    f.namespace[new_name] = f.namespace[old_name]
+    f.namespace.alias(new_name, old_name)
     return i + 1
 
 def w_require(f, i):
@@ -145,11 +158,11 @@ def w_import(f, i):
 def w_call(f, i):
     func = f.stack.pop()
     args = f.stack.pop()
-    # print('f', f, 'args', args)
+    #print('f', f, 'args', args)
     try:
         result = func(*args)
     except:
-        print(f'Error executing {func}{list(args)}')
+        print(f'Error executing {func}({args})')
         raise
     # print('result', result)
     f.stack.push(result)
@@ -189,6 +202,9 @@ def i_semi(forth, i):
     entry = forth.defword(name, word_f)
     entry.inline = forth.compiler.inline
     entry.definition = forth.compiler.instructions
+    #print(name)
+    #for ins in entry.definition:
+    #    print(ins)
     forth.compiler = None
     return i+1
 
@@ -223,6 +239,14 @@ def i_if(forth, i):
     compiler.add_instruction(w_should_not_happen)
     return i+1
 
+def i_ifnot(forth, i):
+    compiler = forth.compiler
+    compiler.add_instruction(w_not)
+    compiler.push_offset()
+    compiler.push_offset()
+    compiler.add_instruction(w_should_not_happen)
+    return i+2
+
 def i_then(forth, i):
     compiler = forth.compiler
     else_offset = compiler.pop_offset()
@@ -252,26 +276,40 @@ def i_do(forth, i):
     compiler.add_instruction(w_should_not_happen)
     return i+1
 
-def i_while(forth, i):
-    compiler = forth.compiler
-    do_offset = compiler.pop_offset()
-    while_offset = compiler.offset()
-    delta = do_offset - while_offset
-    compiler.instructions[if_offset] = ifnot_jump_f(delta)
-    return i+1
-
 def i_begin(forth, i):
     compiler = forth.compiler
     compiler.push_offset()
+    return i
+ 
+def i_while(forth, i):
+    compiler = forth.compiler
+    compiler.push_offset()
+    compiler.add_instruction(w_should_not_happen)
     return i+1
 
-def i_until(forth, i):
+def i_repeat(forth, i):
     compiler = forth.compiler
+    while_offset = compiler.pop_offset()
     begin_offset = compiler.pop_offset()
-    until_offset = compiler.offset()
-    delta = begin_offset - until_offset
-    #print('Delta:', delta)
-    compiler.instructions.append(ifnot_jump_f(delta))
+    repeat_offset = compiler.offset()
+    begin_delta = begin_offset - repeat_offset
+    while_delta = repeat_offset - while_offset + 1
+    print("Begin delta", begin_delta)
+    print("while delta", while_delta)
+    compiler.instructions[while_offset] = ifnot_jump_f(while_delta)
+    compiler.add_instruction(jump_f(begin_delta))
+    return i+1
+
+def w_marker1(f, i):
+    print("marker1")
+    return i+1
+
+def w_marker2(f, i):
+    print("marker3")
+    return i+1
+
+def w_marker3(f, i):
+    print("marker3")
     return i+1
 
 def w_dump(f, i):
diff --git a/sallyforth/data_words.py b/sallyforth/data_words.py
index 26b2a55..d56c2d4 100644
--- a/sallyforth/data_words.py
+++ b/sallyforth/data_words.py
@@ -76,8 +76,10 @@ def w_list(f, ip):    # ->list
 
 def w_thread(f, i):    # @@
     contents = f.stack.pop()
+    print("Contents:", contents)
     result = contents[0]
     for field in contents[1::]:
+        print("Result:", result)
         if isinstance(field, str) and hasattr(result, field):
             result = getattr(result, field)    # result.field
         elif isinstance(field, Arglist):
diff --git a/sallyforth/init.sf b/sallyforth/init.sf
index f1c0b04..d375af4 100644
--- a/sallyforth/init.sf
+++ b/sallyforth/init.sf
@@ -28,8 +28,8 @@
 
 'os import
 
-: expandvars #os.path.expandvars !!1 ;
-: expanduser #os.path.expanduser !!1 ;
+: expandvars #os/path/expandvars !!1 ;
+: expanduser #os/path/expanduser !!1 ;
 : expand expanduser expandvars ;
 
 : tokenize <. $? 'split .> " " swap !!1 ;
@@ -48,4 +48,5 @@
   then
 ;
 
+
 : % "Toggle" p ;
diff --git a/sallyforth/io.sf b/sallyforth/io.sf
index 3d0c4d1..b46a3c2 100644
--- a/sallyforth/io.sf
+++ b/sallyforth/io.sf
@@ -1,12 +1,12 @@
 
-: open builtins.open  !!1 ;
+: open builtins/open  !!1 ;
 : close <. $? 'close .> !!0 drop  ;
 
 : read-file (path -- contents) open dup <. $? 'read .> !!0 swap close ;
 : read-lines (path -- contents) open dup <. $? 'readlines .> !!0 swap close ;
 
 : read-line (prompt -- input-line)
-  builtins.input !!1
+  builtins/input !!1
 ;
 
 \ : read-next nexttoken second ;
diff --git a/sallyforth/kernel.py b/sallyforth/kernel.py
index eba98a2..8ccd1f3 100644
--- a/sallyforth/kernel.py
+++ b/sallyforth/kernel.py
@@ -3,18 +3,10 @@ from os import path
 import basic_words, data_words, operator_words, stack_words, os_words
 from basic_words import const_f, w_enlist
 import tokenstream as ts
+from kword import Keyword
 from stack import Stack
 from namespace import Namespace
 
-def to_number(token):
-    try:
-        return int(token)
-    except ValueError:
-        try:
-            return float(token)
-        except ValueError:
-            return None
-
 class Forth:
     def __init__(self, startup=None):
         self.streams = Stack()
@@ -39,6 +31,7 @@ class Forth:
         self.forth_ns.import_from_module(operator_words)
         self.forth_ns.import_from_module(stack_words)
         self.forth_ns.import_from_module(os_words)
+        self.namespace.alias("*execute-command*", "execute")
 
         self.compiler = None
 
@@ -58,77 +51,71 @@ class Forth:
     def compiling(self):
         return self.compiler
 
-    def _compile_token(self, kind, token):
+    def _compile_token(self, token):
         #print(f"compile: {self.compiler.name}: {token}")
         if self.compiler.name == None:
             #print(f'Compiling {token}')
-            self.compiler.name = token
+            self.compiler.name = token.value
             return
 
-        if kind in ['dqstring', 'sqstring']:
-            self.compiler.add_instruction(const_f(token))
+        if token.isnumber() or token.isstring():
+            self.compiler.add_instruction(const_f(token.value))
             return
 
-        if token in self.namespace:
-            entry = self.namespace[token]
-            #print(token, entry)
-            if entry.immediate:
-                value = entry.get_ivalue()
-                value(self, 0)
-            elif entry.inline:
-                self.compiler.add_instructions(entry.definition[slice(0,-1)])
-            else:
-                value = entry.get_cvalue()
-                self.compiler.add_instruction(value)
+        if token.iskeyword():
+            self.compiler.add_instruction(Keyword(token.value))
             return
 
-        n = to_number(token)
-        if n == None:
+        if token.value not in self.namespace:
             print(f'[{token}]?? Compile of [{self.compiler.name}] terminated.')
             self.compiler = None
+            return
+
+        entry = self.namespace[token.value] 
+
+        if entry.immediate:
+            value = entry.get_ivalue()
+            value(self, 0)
+        elif entry.inline:
+            self.compiler.add_instructions(entry.definition[slice(0,-1)])
         else:
-            self.compiler.add_instruction(const_f(n))
+            value = entry.get_cvalue()
+            self.compiler.add_instruction(value)
 
-    def _eval_token(self, kind, token):
-        #print(f'eval token {token} kind {kind}')
-        if kind in ['dqstring', 'sqstring']:
-            self.stack.push(token)
-            return
-
-        if token in self.namespace:
-            #print("executing ", token)
-            f = self.namespace[token].get_ivalue()
-            #print(f)
-            f(self, 0)
-            return
-
-        n = to_number(token)
-        if n == None:
+    def _eval_token(self, token):
+        #print(f'***Eval token {token}')
+        if token == None:
             print(f'{token}?')
+        elif token.isnumber() or token.isstring():
+            self.stack.push(token.value)
+        elif token.iskeyword():
+            self.stack.push(Keyword(token.value))
+            return
+        elif token.value not in self.namespace:
+            print(f"{token.value}??")
         else:
-            self.stack.push(n)
+            entry = self.namespace[token.value] 
+            f = entry.get_ivalue()
+            f(self, 0)
 
-    def execute_token(self, kind, token):
+    def execute_token(self, token):
         #print(f'execute_token: {token}')
-        kts = self.macro_expand_token(kind, token)
-        #print(kts)
-        for kt in kts:
-            this_kind, this_token = kt
+        expanded_tokens = self.macro_expand_token(token)
+        #print(expanded_tokens)
+        for expanded in expanded_tokens:
             if not self.compiling():
-                #print("interactive", this_token)
-                self._eval_token(this_kind, this_token)
+                self._eval_token(expanded)
             else:
-                #print("compiling...", this_token)
-                self._compile_token(this_kind, this_token)
-        #print("Done")
+                self._compile_token(expanded)
 
     def execute_current_stream(self):
         s = self.streams.peek()
         #print("exec current s:", s)
-        kind, token = s.get_token()
-        while kind != 'eof':
-            self.execute_token(kind, token)
-            kind, token = s.get_token()
+        token = s.get_token()
+        while token:
+            #print("Exec:", token)
+            self.execute_token(token)
+            token = s.get_token()
         self.streams.pop()
 
     def execute_token_stream(self, s):
@@ -140,6 +127,22 @@ class Forth:
         token_stream = ts.string_token_stream(s)
         return self.execute_token_stream(token_stream)
 
+    def resolve_token(self, s):
+        token_stream = ts.string_token_stream(s)
+        token = token_stream.get_token()
+
+        print("token", token)
+
+        if token.isstring():
+            return token.value
+        elif token.isnumber():
+            return token.value
+        elif token.isword():
+            entry = self.namespace[token.value]
+            return entry.get_ivalue()
+        else:
+            return None
+
     def evaluate_string(self, s):
         self.execute_string(s)
         return self.stack.pop()
@@ -154,24 +157,29 @@ class Forth:
         rargs.reverse()
         if rargs:
             for a in rargs:
-                # print("pushing", a);
+                #print("pushing", a);
                 self.stack.push(a)
         #print(f'Before eval stack is {str(self.stack)}')
         return self.evaluate_string(s)
 
 
-    def macro_expand_token(self, kind, token):
-        if len(token) <= 0 or token[0] != '#':
-            return [[kind, token]]
+    def macro_expand_token(self, token):
+        if not token.isword():
+            return [token]
+        elif len(token.value) <= 1:
+            return [token]
+        elif token.value[0] != '#':
+            return [token]
 
-        tag = token[1:]
+        print("Expanding token:", token)
+        tag = token.value[1:]
         parts = tag.split('.')
-        result = [ '<.', parts[0] ]
-        result = [['word', '<.'], ['word', parts[0]]]
+        print("Parts", parts)
+        result = [ ts.Token('word', '<.'), ts.Token('word', parts[0]) ]
         for part in parts[1::]:
-            result.append(['sqstring', part])
-        result.append(['word', '.>'])
-        #print(result)
+            result.append(ts.Token('string', part))
+        result.append(ts.Token('word', '.>'))
+        print(result)
         return result
 
     def set_ns(self, ns_name):
diff --git a/sallyforth/kword.py b/sallyforth/kword.py
new file mode 100644
index 0000000..3081f40
--- /dev/null
+++ b/sallyforth/kword.py
@@ -0,0 +1,12 @@
+from collections import UserString
+
+class Keyword(UserString):
+    def __init__(self, value):
+        value = value[1::]
+        UserString.__init__(self, value)
+
+    def __call__(self, d):
+        return d[self]
+
+    def __repr__(self):
+        return ':' + str(self)
diff --git a/sallyforth/list.sf b/sallyforth/list.sf
index 4d44919..df1690e 100644
--- a/sallyforth/list.sf
+++ b/sallyforth/list.sf
@@ -11,7 +11,7 @@
 : slice (start stop -- slice-obj)
   swap
   2 ->list
-  builtins.slice
+  builtins/slice
   !!
 ;
 
@@ -25,11 +25,11 @@
   [x]
 ;
 
-: repeat (n x -- list-of-x-repeated-n-times)
+: n-of (n x -- list-of-x-repeated-n-times)
   1 ->list * 
 ;
 
-: len builtins.len !!1 ;
+: len builtins/len !!1 ;
 
 : empty? len zero? ;
   
@@ -39,3 +39,9 @@
 
 : ffirst  (list -- first-of-first) first first ;
 : fffirst (list -- fff-irst) first first first ;
+
+: append (x list -- list-with-x-appended)
+  dup tbm 
+  <. $? 'append .> !!1
+  drop
+;
diff --git a/sallyforth/namespace.py b/sallyforth/namespace.py
index 37f2ffd..6ae43e3 100644
--- a/sallyforth/namespace.py
+++ b/sallyforth/namespace.py
@@ -24,6 +24,9 @@ class Namespace:
         self.contents = initial_contents.copy()
         self.refers = refers.copy()
 
+    def alias(self, new_name, existing_name):
+        self.contents[new_name] = self.contents[existing_name]
+
     def refer(self, ns):
         """
         Add the supplied namespace to the refers list.
diff --git a/sallyforth/startup.sf b/sallyforth/startup.sf
index af95258..8203098 100644
--- a/sallyforth/startup.sf
+++ b/sallyforth/startup.sf
@@ -38,7 +38,7 @@
 'current_ns   '*ns*       alias
 
 : *prompt* "Sally> " ;
-: *execute-command* stack execute ;
+: *execute-command* execute ;
 
 \ Make a list.
 'list-marker unique def
@@ -73,7 +73,7 @@
 : }} 
     set-marker [list]                 \ Turn elements into list
     set-marker swap set-marker [list] \ Nest list in argument list
-    builtins.set !!                   \ Call set with 1 argument 
+    builtins/set !!                   \ Call set with 1 argument 
     inline
 ;
 
@@ -83,17 +83,17 @@
 : :] ] ->arglist inline ;
 
 
-: str builtins.str !!1 ;
+: str builtins/str !!1 ;
 
-: type builtins.type !!1 ;
+: type builtins/type !!1 ;
 
 : type? (x class -- bool) swap type = ;
 
-: ctime time.ctime !!0 ;
+: ctime time/ctime !!0 ;
 
-: sleep time.sleep !!1 drop ;
+: sleep time/sleep !!1 drop ;
 
-: callable? builtins.callable !!1 ;
+: callable? builtins/callable !!1 ;
 
 : hello "Hello" . nl ;
 
@@ -114,16 +114,18 @@
 : neg?  0 < inline ;
 : zero? 0 = inline ;
 
-: exists? os.path.exists !!1 ;
+: exists? os/path/exists !!1 ;
 
 : source-if-exists 
   (path -- result-of-sourcing)
+  "SOURCE IF EXISTS" p
+  stack
   dup 
   exists?
   if source else drop then
 ;
 
-: getattr ( obj attr -- attr-value ) swap 2 ->list builtins.getattr !! ;
+: getattr ( obj attr -- attr-value ) swap 2 ->list builtins/getattr !! ;
 
 : .!! (obj args method-name -- result) tbm getattr !! ;
 : .!!0 (obj method-name -- result ) [] swap .!! ;
@@ -132,11 +134,11 @@
 : .!!3 (obj a1 a2 a3 method-name -- result ) swap 3 ->list swap .!! ;
 
 : assert ( bool msg -- )
-  swap
+  p
   if 
-    "OK " . p
+    "OK " p
   else
-    #builtins.AssertionError !!1
+    #builtins/AssertionError !!1
     raise
   then
 ;
diff --git a/sallyforth/string.sf b/sallyforth/string.sf
index dd4271a..c18df47 100644
--- a/sallyforth/string.sf
+++ b/sallyforth/string.sf
@@ -1,4 +1,4 @@
-: split  (delimit str -- tokens) 2 ->list  <. builtins.str 'split .> !! ;
+: split  (delimit str -- tokens) 2 ->list  <. builtins/str 'split .> !! ;
 
 : dot-split (str -- tokens) "." swap split ;
 
diff --git a/sallyforth/test.sf b/sallyforth/test.sf
index 03a238e..5959f6c 100644
--- a/sallyforth/test.sf
+++ b/sallyforth/test.sf
@@ -91,3 +91,13 @@ reset false 1-or-2 2 = "False part of ifelse fires." assert
 [ ] empty? "Empty? knows an empty list." assert
 [ 1 ] empty? not "Empty? knows a non-empty list." assert
 [ 1 2 ] empty? not "Empty? knows a non-empty list." assert
+
+\ Loop
+
+: test-while ( n -- ) -999 swap begin dup zero? while -- repeat -888 ;
+
+5 test-while 3 ->list [ -999 0 -888 ] "While loop works" assert
+
+: zero-trip-while begin false while "Should not get here." repeat ;
+
+888 zero-trip-while 888 = "While should handle zero trip case." assert