Merge pull request #1025 from mathics/addCatchThrow

Add Catch/Throw and With

Author: rocky

mathics/builtin/files.py

@@ -30,7 +30,9 @@
     Complex,
     String,
     Symbol,
+    SymbolFalse,
     SymbolNull,
+    SymbolTrue,
     from_python,
     Integer,
     BoxError,
@@ -4752,8 +4754,8 @@ def apply(self, filename, evaluation):
         path = path_search(path)
 
         if path is None:
-            return Symbol("False")
-        return Symbol("True")
+            return SymbolFalse
+        return SymbolTrue
 
 
 class DirectoryQ(Builtin):
@@ -4795,8 +4797,8 @@ def apply(self, pathname, evaluation):
         path = path_search(path)
 
         if path is not None and osp.isdir(path):
-            return Symbol("True")
-        return Symbol("False")
+            return SymbolTrue
+        return SymbolFalse
 
 
 class Needs(Builtin):

mathics/builtin/scoping.py

@@ -65,12 +65,17 @@ class With(Builtin):
 
     >> n = 10
      = 10
-    >> With[{n = 5}, n ^ 2]
-     = 25
-    >> n
-     = 10
+
+    Evaluate an expression with x locally set to 5:
+
+    'With' works even without evaluation:
+    >> With[{x = a}, (1 + x^2) &]
+     = 1 + a ^ 2&
+
+    Use 'With' to insert values into held expressions
     >> With[{x=y}, Hold[x]]
      = Hold[y]
+    
     >> Table[With[{i=j}, Hold[i]],{j,1,4}]
      = {Hold[1], Hold[2], Hold[3], Hold[4]}
     >> x=5; With[{x=x}, Hold[x]]
@@ -460,6 +465,7 @@ class Contexts(Builtin):
     ## this assignment makes sure that a definition in Global` exists
     >> x = 5;
     X> Contexts[] // InputForm
+
     """
 
     def apply(self, evaluation):

test/helper.py

@@ -1,3 +1,6 @@
+from mathics.core.parser import parse, SingleLineFeeder
+from mathics.core.definitions import Definitions
+from mathics.core.evaluation import Evaluation
 from mathics.session import MathicsSession
 
 session = MathicsSession(add_builtin=True, catch_interrupt=False)

test/test_combinatorica.py

@@ -1,16 +1,10 @@
 # -*- coding: utf-8 -*-
 from .helper import session, check_evaluation
 
-import sys
-from mathics.core.parser import parse, SingleLineFeeder
-from mathics.core.definitions import Definitions
-from mathics.core.evaluation import Evaluation
-import pytest
-
 session.evaluate(
     """
-Needs["DiscreteMath`CombinatoricaV0.9`"]
-     """
+    Needs["DiscreteMath`CombinatoricaV0.9`"]
+    """
 )
 
 # A number of examples from:

test/test_control.py

@@ -1,13 +1,6 @@
 # -*- coding: utf-8 -*-
 from .helper import session, check_evaluation
 
-import sys
-from mathics.core.parser import parse, SingleLineFeeder
-from mathics.core.definitions import Definitions
-from mathics.core.evaluation import Evaluation
-import pytest
-
-
 def test_catch():
     session.evaluate(
         """

test/test_evaluation.py

@@ -46,7 +46,7 @@
         ),
     ],
 )
-def check_evaluation(str_expr: str, str_expected: str, message=""):
+def test_evaluation(str_expr: str, str_expected: str, message=""):
     result = session.evaluate(str_expr)
     expected = session.evaluate(str_expected)