Generalize normalize function

checker/terms.py

@@ -29,8 +29,24 @@ def normalize(term : Term) -> Term:
         Create a normalization function. This function simplifies functions as
         much as possible.
     """
-
     def norm_iter(term : Term) -> Term:
+        """
+            Normalize a single term. Use both the standard normalization scheme
+        """
+        for func in _known_norms:
+            term = func(term)
+        
+        return term
+
+    return traverse(f=norm_iter, term=term)
+
+def register_known_const(name : str, value : Term) -> None:
+    _known_consts[name] = value
+
+def register_known_norm(func : Callable[[Term], Term]) -> None:
+    _known_norms.append(func)
+
+def std_norm_iter(term : Term) -> Term:
     """
         Normalize a single term. Trust that all children values have
         already been normalized, or that they will be normalized later on.
@@ -44,7 +60,7 @@ def normalize(term : Term) -> Term:
         case App():
             match term.f:
                 case Lambda():
-                        return term.f.substitute(value=norm_iter(term.x))
+                    return term.f.substitute(value=term.x)
                 
                 case _:
                     return term
@@ -60,17 +76,16 @@ def normalize(term : Term) -> Term:
     
         case Term():
             return term
-
-    return traverse(f=norm_iter, term=term)
-
-def register_known_const(name : str, value : Term) -> None:
-    _known_consts[name] = value
+_known_norms.append(std_norm_iter)
 
 def traverse(f : Callable[[Term], Term], term : Term) -> Term:
     """
         Traverse through the tree back-and-forth, aiming to run the given
         function as thoroughly as possible to manipulate the term tree.
 
+        The function quits once no more operations are created.
+        **WARNING:** This means the tree might traverse forever.
+
         :param f: The traversal function that replaces terms.
         :type f: Callable[[Term], Term]
         :param term: The term to traverse.
@@ -78,7 +93,12 @@ def traverse(f : Callable[[Term], Term], term : Term) -> Term:
         :return: The result of the traversed term.
         :rtype: Term
     """
-    return traverse_bottom_up(f=f, term=traverse_top_down(f=f, term=term))
+    a, b = Term(), term
+
+    while a != b:
+        a, b = b, traverse_bottom_up(f=f, term=traverse_top_down(f=f, term=term))
+    
+    return b
 
 def traverse_bottom_up(f : Callable[[Term], Term], term : Term) -> Term:
     """