Weird changes needed...

_ListPlot[] needs to evaluate its arguements in order to check them!
There is this weird place in caching where we were caching the
Expression form of a ListExpression. This is something that has been
plaguing our code. Finding and fixing these simplifies coding speeds up
execution.

mathics/builtin/drawing/plot.py

@@ -301,6 +301,16 @@ def eval(self, points, evaluation: Evaluation, options: dict):
 
         class_name = self.__class__.__name__
 
+        # Scale point values down by Log 10. Tick mark values will be adjusted to be 10^n in GraphicsBox.
+        if self.use_log_scale:
+            points = ListExpression(
+                *(
+                    Expression(SymbolLog10, point).evaluate(evaluation)
+                    for point in points
+                )
+            )
+
+        points = points.evaluate(evaluation)
         if not isinstance(points, ListExpression):
             evaluation.message(class_name, "lpn", points)
             return
@@ -315,15 +325,6 @@ def eval(self, points, evaluation: Evaluation, options: dict):
             evaluation.message(class_name, "lpn", points)
             return
 
-        # Scale point values down by Log 10. Tick mark values will be adjusted to be 10^n in GraphicsBox.
-        if self.use_log_scale:
-            points = ListExpression(
-                *(
-                    Expression(SymbolLog10, point).evaluate(evaluation)
-                    for point in points
-                )
-            )
-
         # If "points" is a literal value with a Python representation,
         # it has a ".value" attribute with a non-None value. So here,
         # we don't have to eval_N().to_python().

mathics/core/expression.py

@@ -1410,8 +1410,12 @@ def rules():
                 if not isinstance(result, EvalMixin):
                     return result, False
                 if result.sameQ(new):
-                    new._timestamp_cache(evaluation)
-                    return new, False
+                    # Even though result and new may be the same,
+                    # new can be a Expression[SymbolConstant: System`List...]
+                    # while "result' might be ListExpression!?
+                    # So make sure to use "result", not "new".
+                    result._timestamp_cache(evaluation)
+                    return result, False
                 else:
                     return result, True
 

mathics/eval/drawing/plot.py

@@ -201,14 +201,14 @@ def eval_ListPlot(
             [xx for xx, yy in plot_groups], [xx for xx, yy in plot_groups], x_range
         )
         plot_groups = [plot_groups]
-    elif all(isinstance(line, list) for line in plot_groups):
-        if not all(isinstance(line, list) for line in plot_groups):
+    elif all(isinstance(line, (list, tuple)) for line in plot_groups):
+        if not all(isinstance(line, (list, tuple)) for line in plot_groups):
             return
 
         # He have a list of plot groups
         if all(
-            isinstance(point, list) and len(point) == 2
-            for plot_group in plot_groups
+            isinstance(point, (list, tuple)) and len(point) == 2
+            for _ in plot_groups
             for point in plot_groups
         ):
             pass