diff --git a/sallyforth/arglist.py b/sallyforth/arglist.py
new file mode 100644
index 0000000..d7b9b31
--- /dev/null
+++ b/sallyforth/arglist.py
@@ -0,0 +1,2 @@
+class Arglist(list):
+    pass
diff --git a/sallyforth/kernel.py b/sallyforth/kernel.py
index 73019c2..e4655cb 100644
--- a/sallyforth/kernel.py
+++ b/sallyforth/kernel.py
@@ -4,6 +4,7 @@ from words import *
 import words
 from lex import forth_prompt, read_tokens, is_string, tokenize
 from stack import Stack
+from namespace import Namespace
 
 def to_number(token):
     try:
@@ -17,31 +18,33 @@ def to_number(token):
 class Forth:
     def __init__(self, startup=None):
         self.stack = Stack()
-        self.dictionary = {
+        self.namespaces = {}
+        initial_defs = {
                 '*prompt*': const_f('SallyForth>> '),
                 'true': const_f(True),
                 'false': const_f(False),
                 'nil': const_f(None),
                 '0': const_f(0),
                 '1': const_f(1),
-                '2': const_f(2) }
+                '2': const_f(2)}
 
-        self.import_from_module(words, 'w_')
+        self.forth_ns = self.make_namespace('forth', initial_defs)
+        user_ns = self.make_namespace('user', {}, [self.forth_ns])
+
+        self.forth_ns.import_from_module(words, 'w_')
+        self.namespace = self.forth_ns
 
         self.compiler = None
-        if startup:
-            execute_startup(startup)
 
-    def import_from_module(self, m, prefix):
-        names = dir(m)
-        prefix_len = len(prefix)
-        for name in names:
-            if name.startswith(prefix):
-                word_name = name[prefix_len::]
-                self.dictionary[word_name] = m.__getattribute__(name)
+        self.defvar("argv", sys.argv[1::])
+
+        if startup:
+            self.execute_file(startup)
+
+        self.namespace = user_ns
 
     def defvar(self, name, value):
-        self.dictionary[name] = const_f(value)
+        self.namespace[name] = const_f(value)
 
     def evaluate_token(self, token):
         self.execute_token(token)
@@ -62,8 +65,22 @@ class Forth:
             else:
                 self.compile_token(token)
 
+    def set_ns(self, ns_name):
+        if ns_name in self.namespaces:
+            self.namespace = self.namespaces[ns_name]
+        else:
+            raise ValueError(f'No such namespace: {ns_name}')
+
+    def make_namespace(self, ns_name, initial_defs={}, refers=[]):
+        print(f'New namespace {ns_name} {refers}')
+        result = Namespace(ns_name, initial_defs, refers)
+        self.namespaces[ns_name] = result
+        print(f'Returning {result}')
+        return result
+
     def execute_file(self, fpath):
-        old_source = self.dictionary.get('*source*', None)
+        old_source = self.namespace.get('*source*', None)
+        old_namespace = self.namespace
         self.defvar('*source*', fpath)
         with open(fpath) as f:
             line = f.readline()
@@ -71,8 +88,8 @@ class Forth:
                 tokens = tokenize(line)
                 self.execute_tokens(tokens)
                 line = f.readline()
-        self.defvar('*source*', '')
-        self.dictionary['*source*'] = old_source
+        self.namespace['*source*'] = old_source
+        self.namespace = old_namespace
 
     def compile_token(self, token):
         if self.compiler.name == None:
@@ -83,28 +100,29 @@ class Forth:
             self.compiler.add_instruction(const_f(token[1::]))
             return
 
-        if token in self.dictionary:
-            word = self.dictionary[token]
+        if token in self.namespace:
+            word = self.namespace[token]
             if 'immediate' in word.__dict__:
                 word(self, 0)
             else:
-                self.compiler.add_instruction(self.dictionary[token])
+                self.compiler.add_instruction(self.namespace[token])
             return
 
         n = to_number(token)
         if n == None:
+            print(f'{token}? Compile of {self.compiler.name} terminated.')
             self.compiler = None
-            print(f'{token}? Compile terminated.')
         else:
             self.compiler.add_instruction(const_f(n))
 
     def execute_token(self, token):
+        # print("x token:", token)
         if is_string(token):
             self.stack.push(token[1::])
             return
 
-        if token in self.dictionary:
-            self.dictionary[token](self, 0)
+        if token in self.namespace:
+            self.namespace[token](self, 0)
             return
 
         n = to_number(token)
@@ -116,5 +134,5 @@ class Forth:
     def dump(self):
         print('Forth:', self)
         print('Stack:', self.stack)
-        print('Dictionary:', self.dictionary)
+        print('Dictionary:', self.namespace)
         print('Compiler:', self.compiler)
diff --git a/sallyforth/namespace.py b/sallyforth/namespace.py
new file mode 100644
index 0000000..5d11ab1
--- /dev/null
+++ b/sallyforth/namespace.py
@@ -0,0 +1,86 @@
+class Namespace:
+    def __init__(self, name, initial_contents={}, refers=[]):
+        print('name', name)
+        print('initial contents', initial_contents)
+        print('refers', refers)
+        print('===')
+        self.name = name
+        self.contents = initial_contents.copy()
+        self.refers = refers.copy()
+
+    def refer(self, ns):
+        """
+        Add the supplied namespace to the refers list.
+        """
+        self.refers.append(ns)
+
+    def import_from_module(self, m, prefix):
+        """
+        Import all of the word defining functions in
+        module m whose function names start with prefix
+        into this namespace. Removes the prefix.
+        """
+        names = dir(m)
+        prefix_len = len(prefix)
+        for name in names:
+            if name.startswith(prefix):
+                word_name = name[prefix_len::]
+                self[word_name] = m.__getattribute__(name)
+
+    def keys(self):
+        return self.contents.keys()
+
+    def all_keys(self):
+        result = set(self.contents.keys())
+        for r in self.refers:
+            result = result.union(set(r.contents.keys()))
+        return result
+
+    def get(self, key, default):
+        if not self.__contains__(key):
+            return default
+        return self[key]
+        
+    def __contains__(self, key):
+        if self.contents.__contains__(key):
+            return True
+        for r in self.refers:
+            if r.__contains__(key):
+                return True
+        return False
+
+    def local_contains(self, key):
+        return self.contents.__contains__(key)
+
+    def __delattr__(self, key):
+        return self.contents.__delattr__(key)
+
+    def __setitem__(self, key, x):
+        self.contents[key] = x
+
+    def __iter__(self):
+        return self.contents.__iter__()
+
+    def __getitem__(self, key):
+        # print("get item", key, self.contents)
+        if key in self.contents:
+            return self.contents[key]
+        # print("not in local ns")
+        for imp in self.refers:
+            # print("trying ", imp)
+            if key in imp:
+                return imp[key]
+        # print("not found")
+        raise KeyError(key)
+
+    def __str__(self):
+        return f'Namespace({self.name})'
+
+if __name__ == '__main__':
+    print("main program")
+    x = Namespace('x', {'a': 1, 'b': 2})
+    print(x['a'])
+    y = Namespace('y', {'c': 3, 'd': 4})
+    print(y['c'])
+    y.refer(x)
+    print(y['a'])
diff --git a/sallyforth/sallyforth.py b/sallyforth/sallyforth.py
index 95cb31f..45da16b 100644
--- a/sallyforth/sallyforth.py
+++ b/sallyforth/sallyforth.py
@@ -4,6 +4,7 @@ import atexit
 from kernel import Forth
 from lex import tokenize
 import readline
+import traceback
 
 HistoryFile=".sallyforth"
 
@@ -13,7 +14,7 @@ class Completer:
     def __init__(self, f):
         self.f = f
     def complete(self, prefix, index):
-        self.matching_words = [w for w in self.f.dictionary.keys() if w.startswith(prefix) ]
+        self.matching_words = [w for w in self.f.namespace.all_keys() if w.startswith(prefix) ]
         try:
             return self.matching_words[index]
         except IndexError:
@@ -32,14 +33,14 @@ def setup_readline(history_path, f):
     atexit.register(save_history)
 
 def setup_forth():
-    f = Forth()
-    f.defvar("argv", sys.argv[1::])
-
     source_dir = os.path.dirname(os.path.abspath(__file__))
     startup_file = f'{source_dir}/startup.sf'
 
     if os.path.exists(startup_file):
-        f.execute_file(startup_file)
+        f = Forth(startup_file)
+    else:
+        f = Forth()
+
 
     return f
 
@@ -62,6 +63,7 @@ def repl(f):
             print("Error:", exc_type)
             print("Error:", exc_value)
             print("Error:", exc_traceback)
+            traceback.print_tb(exc_traceback)
     
 
 if __name__ == "__main__":
diff --git a/sallyforth/stack.py b/sallyforth/stack.py
index 5b19828..c7e654a 100644
--- a/sallyforth/stack.py
+++ b/sallyforth/stack.py
@@ -18,6 +18,10 @@ class Stack:
             self.top = -1;
         return result
 
+    def __iter__(self):
+        for i in range(self.top, -1, -1):
+            yield self.stack[i]
+
     def peek(self):
         return self.stack[self.top]
 
diff --git a/sallyforth/startup.sf b/sallyforth/startup.sf
index a07536a..88bab3c 100644
--- a/sallyforth/startup.sf
+++ b/sallyforth/startup.sf
@@ -17,6 +17,7 @@
 'semi         ';          alias
 'bounded_list '[list]     alias
 'list         '->list     alias
+'to_arglist   '->arglist  alias
 'list_to_map  'list->map  alias
 'lookup       '@@         alias
 'call         '!!         alias
@@ -29,6 +30,7 @@
 'le           '<=         alias
 'ge           '>=         alias
 'eq           '=          alias
+'current_ns   '*ns*       alias
 
 : *prompt* "Sally> " ;
 
@@ -54,18 +56,25 @@
 
 : {{}} ( -- <empty set>) {{ }} ;
 
-: type (x -- type-of-x) 1 ->list builtins.type !! ;
+: [: [ ;
+: :] ] ->arglist ;
 
-: px0 (mod fname -- result) []  px ;
-: px1 (mod fname arg -- result) 1 ->list px ;
-: px2 (mod fname arg arg -- result) 2 ->list px ;
-: px3 (mod fname arg arg arg -- result) 3 ->list px ;
+: => [ ;
+: >! ] arrow ;
+
+: <. [ ;
+: .> ] arrow ;
+
+: !!0 [] swap call ;
+
+: type 1 ->list builtins.type !! ;
 
-: dir (mod -- keys) "dir" px0 ;
 : ctime [] time.ctime ;
 : sleep 1 ->list stack time.sleep drop ;
 
-: hello (simple greeting) "Hello" . nl ;
+: callable? 1 ->list builtins.callable ;
+
+: hello "Hello" . nl ;
 
 : >0 0 > ;
 : <0 0 < ;
@@ -75,20 +84,22 @@
 : p . nl ;
 : top dup p ;
 
-: -- ( n -- n-1 ) -1 + ;
-: ++ ( n -- n+1 ) 1 + ;
-: pos? (n -- bool) 0 > ;
-: neg? (n -- bool) 0 < ;
-: zero? (n -- bool) 0 = ;
+: --  -1 + ;
+: ++  1 + ;
+: pos?  0 > ;
+: neg?  0 < ;
+: zero? 0 = ;
 
-: source-if-exists (path --)
+: source-if-exists 
+    (path --)
     dup 
     1 ->list os.path.exists
     if source else drop then
 ;
 
 : << [ ;
-: >> ] @@ ;
+: >>@ ] @@ ;
+: >>! ] @@ [] swap !! ;
 
 "init.sf" source-if-exists
 
diff --git a/sallyforth/words.py b/sallyforth/words.py
index bcddbe4..c4435b2 100644
--- a/sallyforth/words.py
+++ b/sallyforth/words.py
@@ -1,6 +1,7 @@
-from compiler import Compiler
-import importlib
 from inspect import isfunction, isbuiltin
+import importlib
+from compiler import Compiler
+from arglist import Arglist
 
 class Unique:
     def __str__(self):
@@ -30,18 +31,31 @@ def import_native_module(forth, m, alias=None, excludes=[]):
         #print(localname)
         val = m.__getattribute__(name)
         if isfunction(val) or isbuiltin(val):
-            forth.dictionary[localname] = native_function_handler(val)
+            forth.namespace[localname] = native_function_handler(val)
         else:
-            forth.dictionary[localname] = const_f(val)
+            forth.namespace[localname] = const_f(val)
 
 def w_forth(f, i):
     f.stack.push(f)
     return i+1
 
+def w_current_ns(f, i):
+    f.stack.push(f.namespace)
+    return i + 1
+
+def w_ns(f, i):
+    name = f.stack.pop()
+    if name in f.namespaces:
+        f.namespace = f.namespaces[name]
+    else:
+        new_ns = f.make_namespace(name, {}, [f.forth_ns])
+        f.namespace = new_ns
+    return i + 1
+
 def w_alias(f, i):
     new_name = f.stack.pop() 
     old_name = f.stack.pop() 
-    f.dictionary[new_name] = f.dictionary[old_name]
+    f.namespace[new_name] = f.namespace[old_name]
     return i + 1
 
 def w_require(f, i):
@@ -91,7 +105,7 @@ def w_recur(f, i):
 def w_import(f, i):
     name = f.stack.pop()
     m = importlib.import_module(name)
-    f.dictionary[name] = const_f(m)
+    f.namespace[name] = const_f(m)
     return i+1
 
 def w_call(f, i):
@@ -105,15 +119,10 @@ def w_call(f, i):
 
 def w_px(f, i):
     args = f.stack.pop()
-    #print('args', args)
     name = f.stack.pop()
-    #print('name', name)
     m = f.stack.pop()
-    #print('mod:', m)
     func = m.__dict__[name]
-    #print('f:', f);
     result = func(*args)
-    #print('result', result)
     f.stack.push(result)
     return i+1
 
@@ -136,16 +145,20 @@ def w_bounded_list(f, ip):
     f.stack.push(l)
     return ip+1
 
+def w_to_arglist(f, ip):
+    l = f.stack.pop()
+    f.stack.push(Arglist(l))
+    return ip+1
+
 def w_list(f, ip):    # ->list
     n = f.stack.pop()
     l = []
     for i in range(n):
         l.append(f.stack.pop())
-    #print(l)
     f.stack.push(l)
     return ip+1
 
-def w_lookup(f, i):    # @@
+def qqw_lookup(f, i):    # @@
     l = f.stack.pop()
     value = l[0]
     for field in l[1::]:
@@ -153,6 +166,29 @@ def w_lookup(f, i):    # @@
     f.stack.push(value)
     return i+1
 
+def w_lookup(f, i):    # ->
+    value = f.stack.pop()
+    fields = f.stack.pop()
+    print(f'value {value} fields {fields}')
+
+    if not isinstance(fields, list):
+        fields = [fields]
+
+    for field in fields:
+        print(f'value {value} field {field}')
+        if isinstance(field, str) and hasattr(value, field):
+            print("->getattr")
+            value = getattr(value, field)
+        elif isinstance(field, Arglist):
+            print("->arglist")
+            value = value(*field)
+        else:
+            print("index")
+            value = value[field]
+    f.stack.push(value)
+    return i+1
+
+
 ListMarker = object()
 
 def w_startlist(f, i):   # [
@@ -213,6 +249,23 @@ def w_getattribute(f, i):
     f.stack.push(result)
     return i+1
 
+def w_arrow(f, i):    # ->
+    contents = f.stack.pop()
+    result = contents[0]
+    for field in contents[1::]:
+        print(f'result {result} field {field}')
+        if isinstance(field, str) and hasattr(result, field):
+            print("->getattr")
+            result = getattr(result, field)
+        elif isinstance(field, Arglist):
+            print("->arglist")
+            result = result(*field)
+        else:
+            print("index")
+            result = result[field]
+    f.stack.push(result)
+    return i+1
+
 def w_def(f, i):
     value = f.stack.pop()
     name = f.stack.pop()
@@ -322,7 +375,7 @@ def w_semi(forth, i):
     forth.compiler.add_instruction(w_return)
     name = forth.compiler.name
     word_f = execute_f(name, forth.compiler.instructions)
-    forth.dictionary[name] = word_f
+    forth.namespace[name] = word_f
     forth.compiler = None
     return i+1
 
@@ -419,5 +472,8 @@ def w_idump(f, i):
 w_idump.__dict__['immediate'] = True
 
 def w_stack(f, i):
-    print(f'Stack: <B[{f.stack}]T>')
+    print("::top::")
+    for x in f.stack:
+        print(f'{x}')
+    print("::bottom::")
     return i+1