some more (and admittedly rather mechanic) object overhaul.

object.py

 # This file is part of the Python Lambda Experiment (pyle),
-# Copyright (C) 2017 Juergen Nickelsen <ni@w21.org>.
+# Copyright (C) 2017, 2018 Juergen Nickelsen <ni@w21.org>.
 # See LICENSE for the conditions under which this code is licensed to you.
 
 import re
@@ -59,8 +59,7 @@ def p2l(value):
 
 
 class Object:
-
-    """This is the base class for all objects, intended as purely abstract.
+    """This is the base class for all Pyle objects, purely abstract.
     
     There are a few default functions.
     
@@ -118,42 +117,86 @@ class Object:
         """Return object's attributes as a dict."""
         return { "type": intern(self.typename()), "id": id(self) }
     
-    def car(self): raise PyleArgTypeError(self, 'car', 'list')
+    def car(self):
+        """Return the car of a cons.
+
+        If this is not a cons => error.
+        """
+        raise PyleArgTypeError(self, 'car', 'list')
     
-    def cdr(self): raise PyleArgTypeError(self, 'cdr', 'list')
+    def cdr(self):
+        """Return the cdr of a cons.
+
+        If this is not a cons => error.
+        """
+        raise PyleArgTypeError(self, 'cdr', 'list')
     
-    def rplaca(self, ob): raise PyleArgTypeError(self, 'rplaca', 'pair')
+    def rplaca(self, ob):
+        """Replace the car of a cons.
+
+        If this is not a cons => error.
+        """
+        raise PyleArgTypeError(self, 'rplaca', 'pair')
     
-    def rplacd(self, ob): raise PyleArgTypeError(self, 'rplacd', 'pair')
+    def rplacd(self, ob):
+        """Replace the cdr of a cons.
+
+        If this is not a cons => error.
+        """
+        raise PyleArgTypeError(self, 'rplacd', 'pair')
     
-    def isAtom(self): return False
+    def isAtom(self):
+        """Return true iff the object is an Atom. False by default."""
+        return False
     
-    def isEnvironment(self): return False
+    def isEnvironment(self):
+        """Return true iff this is an environment. False by default."""
+        return False
     
-    def isFunction(self): return False
+    def isFunction(self):
+        """Return true iff this is a function. False by default."""
+        return False
     
-    def isList(self): return False
+    def isList(self):
+        """Return true iff this is a list. False by default."""
+        return False
     
-    def isMacro(self): return False
+    def isMacro(self):
+        """Return true iff this is a macro. False by default."""
+        return False
     
-    def isNumber(self): return False
+    def isNumber(self):
+        """Return true iff this is a number. False by default."""
+        return False
     
-    def isPair(self): return False
+    def isPair(self):
+        """Return true iff this is a pair. False by default."""
+        return False
     
-    def isString(self): return False
+    def isString(self):
+        """Return true iff this is a string. False by default."""
+        return False
     
-    def isSymbol(self): return False
+    def isSymbol(self):
+        """Return true iff this is a symbol. False by default."""
+        return False
     
-    def isError(self): return False
+    def isError(self):
+        """Return true iff this is an error. False by default."""
+        return False
 
 
 class Error(Object):
+    """Error class. These are derived from the Pyle exceptions."""
+    
     def __init__(self, e):
         self.e = e              # the Python exception
         errName = re.sub("^Pyle", "", e.__class__.__name__)
         self.e.kind = intern(utils.dashify(errName))
+        
     def isError(self):
         return True
+    
     def __str__(self):
         elems = ["#<Error"]
         firstSem = ""
@@ -162,8 +205,10 @@ class Error(Object):
             firstSem = ";"
         elems.append(">")
         return "".join(elems)
+    
     def __repr__(self):
         return str(self)
+    
     def describe(self):
         attrs = super().describe()
         attrs.update(self.e.__dict__)