More suggestions and fixes (#595)

* add `Remove`. Fix load definitions. Normalize assignment for MakeBoxes

* support strings

CHANGES.rst

@@ -17,6 +17,7 @@ New Builtins
 #. ``Curl`` (2-D and 3-D vector forms only)
 #. ``Kurtosis``
 #. ``PauliMatrix``
+#. ``Remove``
 #. ``SetOptions``
 #. ``SixJSymbol``
 #. ``Skewness``

SYMBOLS_MANIFEST.txt

@@ -831,6 +831,7 @@ System`RegularExpression
 System`RegularPolygon
 System`RegularPolygonBox
 System`ReleaseHold
+System`Remove
 System`RemoveDiacritics
 System`RenameDirectory
 System`RenameFile

mathics/autoload/forms/StandardForm.m

@@ -12,7 +12,7 @@
    code. *)
 Attributes[CommonRadicalBox] = HoldAll;
 Attributes[RadBox] = HoldAll;
-CommonRadicalBox[expr_, form_] = RadBox[MakeBoxes[expr, form], 3];
+CommonRadicalBox[expr_, form_]:= RadBox[MakeBoxes[expr, form], 3];
 
 (******************************************************************************************)
 (* StandardForm Boxing Rules                                                               *)

mathics/builtin/assignments/clear.py

@@ -166,6 +166,36 @@ def do_clear(self, definition):
         definition.defaultvalues = []
 
 
+class Remove(Builtin):
+    """
+    <dl>
+      <dt>'Remove[$x$]'
+      <dd>removes the definition associated to $x$.
+    </dl>
+    >> a := 2
+    >> Names["Global`a"]
+     = {a}
+    >> Remove[a]
+    >> Names["Global`a"]
+     = {}
+    """
+
+    attributes = A_HOLD_ALL | A_LOCKED | A_PROTECTED
+    messages = {"ssym": "`1` is not a symbol."}
+    precedence = 670
+    summary_text = "remove the definition of a symbol"
+
+    def eval(self, symb, evaluation):
+        """Remove[symb_]"""
+        if isinstance(symb, Symbol):
+            evaluation.definitions.reset_user_definition(symb.name)
+        elif isinstance(symb, String):
+            evaluation.definitions.reset_user_definition(symb.value)
+        else:
+            evaluation.message(self.get_name(), "ssym", symb)
+        return SymbolNull
+
+
 class Unset(PostfixOperator):
     """
     <dl>

mathics/builtin/assignments/internals.py

@@ -567,9 +567,12 @@ def process_assign_makeboxes(self, lhs, rhs, evaluation, tags, upset):
     #   MakeBoxes[CubeRoot, StandardForm] := RadicalBox[3, StandardForm]
     # rather than:
     #   MakeBoxes[CubeRoot, StandardForm] -> RadicalBox[3, StandardForm]
-    makeboxes_rule = Rule(lhs, rhs, system=True)
-    makeboxes_defs = evaluation.definitions.builtin["System`MakeBoxes"]
-    makeboxes_defs.add_rule(makeboxes_rule)
+
+    makeboxes_rule = Rule(lhs, rhs, system=False)
+    definitions = evaluation.definitions
+    definitions.add_rule("System`MakeBoxes", makeboxes_rule, "down")
+    #    makeboxes_defs = evaluation.definitions.builtin["System`MakeBoxes"]
+    #    makeboxes_defs.add_rule(makeboxes_rule)
     return True
 
 

mathics/core/definitions.py

@@ -169,7 +169,14 @@ def __init__(
                 if name.startswith("Global`"):
                     raise ValueError("autoload defined %s." % name)
 
-            self.builtin.update(self.user)
+            # The idea here is that all the symbols loaded in
+            # autoload become converted in builtin.
+            # For some reason, if we do not do this here,
+            # `Export` and `Import` fails.
+            # TODO: investigate why.
+            for name in self.user:
+                self.builtin[name] = self.get_definition(name)
+
             self.user = {}
             self.clear_cache()