Merge pull request #1213 from mathics/SymbolList

Singletonize Symbol System`List

Author: rocky

mathics/builtin/arithmetic.py

@@ -39,6 +39,8 @@
     SymbolNull,
     SymbolSequence,
     SymbolTrue,
+    SymbolSequence,
+    from_python,
     from_mpmath,
     from_python,
 )

mathics/builtin/inout.py

@@ -37,7 +37,7 @@
     PrecisionReal,
     SymbolList,
     SymbolMakeBoxes,
-    SymbolRule,
+    SymbolRule
 )
 from mathics.core.numbers import (
     dps,

mathics/core/evaluation.py

@@ -13,7 +13,7 @@
 from mathics_scanner import TranslateError
 
 from mathics import settings
-from mathics.core.expression import ensure_context, KeyComparable, SymbolAborted
+from mathics.core.expression import ensure_context, KeyComparable, SymbolAborted, SymbolList, SymbolNull
 
 FORMATS = [
     "StandardForm",
@@ -250,7 +250,7 @@ def __init__(
         self.format = format
         self.catch_interrupt = catch_interrupt
 
-        self.SymbolNull = Symbol("Null")
+        self.SymbolNull = SymbolNull
 
         # status of last evaluate
         self.exc_result = self.SymbolNull
@@ -458,7 +458,7 @@ def format_output(self, expr, format=None):
     def set_quiet_messages(self, messages) -> None:
         from mathics.core.expression import Expression
 
-        value = Expression("List", *messages)
+        value = Expression(SymbolList, *messages)
         self.definitions.set_ownvalue("Internal`$QuietMessages", value)
 
     def get_quiet_messages(self):

mathics/core/expression.py

@@ -2024,6 +2024,15 @@ def __getnewargs__(self):
 SymbolRule = Symbol("Rule")
 SymbolSequence = Symbol("Sequence")
 SymbolTrue = Symbol("True")
+SymbolAborted = Symbol("$Aborted")
+SymbolInfinity = Symbol("Infinity")
+SymbolList = Symbol("List")
+SymbolByteArray = Symbol("ByteArray")
+SymbolAssociation = Symbol("Association")
+SymbolMakeBoxes = Symbol("MakeBoxes")
+SymbolN = Symbol("N")
+SymbolRule = Symbol("Rule")
+SymbolSequence = Symbol("Sequence") 
 
 
 @lru_cache(maxsize=1024)