Add SymbolNull ...

Try speeding up workflows testing using "make -j3"

Author: rocky

.github/workflows/basic.yml

@@ -29,4 +29,4 @@ jobs:
     - name: Test Mathics
       run: |
         pip install pytest pexpect
-        make check
+        make -j3 check

mathics/core/expression.py

@@ -1778,7 +1778,7 @@ def to_python(self, *args, **kwargs):
             return True
         if self == SymbolFalse:
             return False
-        if self.name == 'System`Null':
+        if self == SymbolNull:
             return None
         n_evaluation = kwargs.get('n_evaluation')
         if n_evaluation is not None:
@@ -1846,8 +1846,10 @@ def user_hash(self, update) -> None:
     def __getnewargs__(self):
         return (self.name, self.sympy_dummy)
 
+# Some common Symbols
 SymbolTrue = Symbol("True")
 SymbolFalse = Symbol("False")
+SymbolNull = Symbol("Null")
 
 class Number(Atom):
     def __str__(self) -> str:

mathics/core/numbers.py

@@ -51,10 +51,10 @@ def _get_float_inf(value, evaluation) -> typing.Optional[float]:
 
 
 def get_precision(value, evaluation) -> typing.Optional[int]:
-    from mathics.core.expression import Symbol, MachineReal
     if value.get_name() == 'System`MachinePrecision':
         return None
     else:
+        from mathics.core.expression import Symbol, MachineReal
         dmin = _get_float_inf(Symbol('$MinPrecision'), evaluation)
         dmax = _get_float_inf(Symbol('$MaxPrecision'), evaluation)
         d = value.round_to_float(evaluation)