gh-37395: build/pkgs/mathics: Reduce to a pip package

    
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Our Mathics package is outdated (and also the interface shows test
failures in CI - e.g. in https://github.com/sagemath/sage/actions/runs/7
894201915/job/21638423818#step:14:3279)

Trying to update Mathics reveals more dependencies, include scikit-image
and llvm-lite.

Here we reduce it to a "pip" package to simplify maintenance of the
package on our side.

The latest released version 6.0.4 fails to install in Sage because of
rigid version constraints.

We are using the current HEAD version (7.0.0dev), which includes
- Mathics3/mathics-core#1014
- Mathics3/mathics-core#1034

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URL: #37395
Reported by: Matthias Köppe
Reviewer(s): Matthias Köppe, Sebastian Oehms

build/pkgs/mathics/dependencies

@@ -1,4 +1,4 @@
- | $(PYTHON_TOOLCHAIN) pint palettable mathics_scanner $(PYTHON)
+numpy pillow mpmath dateutil requests sympy pyyaml charset_normalizer typing_extensions | $(PYTHON_TOOLCHAIN) $(PYTHON)
 
 ----------
 All lines of this file are ignored except the first.

build/pkgs/mathics/requirements.txt

@@ -0,0 +1,3 @@
+Mathics3 @ git+https://github.com/Mathics3/mathics-core
+mathics-scanner @ git+https://github.com/Mathics3/mathics-scanner
+-c ${SAGE_VENV}/var/lib/sage/scripts/numpy/spkg-requirements.txt

src/sage/doctest/external.py

@@ -356,7 +356,9 @@ def external_features():
     import sage.features.ffmpeg
     yield from sage.features.ffmpeg.all_features()
     import sage.features.interfaces
-    yield from sage.features.interfaces.all_features()
+    for feature in sage.features.interfaces.all_features():
+        if feature.name != 'mathics':
+            yield feature
     from sage.features.mip_backends import CPLEX, Gurobi
     yield CPLEX()
     yield Gurobi()

src/sage/features/interfaces.py

@@ -91,6 +91,23 @@ def _is_present(self):
                                      reason=f"Interface {interface} is not functional: {exception}")
 
 
+class Mathics(InterfaceFeature):
+    r"""
+    A :class:`~sage.features.Feature` describing whether :class:`sage.interfaces.mathics.Mathics`
+    is present and functional.
+
+    EXAMPLES::
+
+        sage: from sage.features.interfaces import Mathics
+        sage: Mathics().is_present()  # not tested
+        FeatureTestResult('mathics', False)
+    """
+
+    @staticmethod
+    def __classcall__(cls):
+        return InterfaceFeature.__classcall__(cls, 'mathics', 'sage.interfaces.mathics')
+
+
 # The following are provided by external software only (no SPKG)
 
 class Magma(InterfaceFeature):
@@ -223,6 +240,7 @@ def all_features():
         [Feature('magma'),
          Feature('matlab'),
          Feature('mathematica'),
+         Feature('mathics'),
          Feature('maple'),
          Feature('macaulay2'),
          Feature('octave'),
@@ -231,6 +249,7 @@ def all_features():
     return [Magma(),
             Matlab(),
             Mathematica(),
+            Mathics(),
             Maple(),
             Macaulay2(),
             Octave(),

src/sage/interfaces/mathics.py

@@ -341,7 +341,7 @@
 ::
 
     sage: mathics('10.^80')         # optional - mathics
-    1.*^80
+    1.×10^80
     sage: mathics('10.^80').sage()  # optional - mathics
     1.00000000000000e80
 
@@ -483,6 +483,7 @@ def __init__(self,
         self._seed = seed
         self._initialized = False  # done lazily
         self._session = None
+        os.environ['MATHICS_CHARACTER_ENCODING'] = 'ASCII'  # see :issue:`37395`
 
     def _lazy_init(self):
         r"""
@@ -512,6 +513,8 @@ def _start(self):
         """
         if not self._session:
             from mathics.session import MathicsSession
+            from mathics.core.load_builtin import import_and_load_builtins
+            import_and_load_builtins()
             self._session = MathicsSession()
             from sage.interfaces.sympy import sympy_init
             sympy_init()
@@ -601,7 +604,7 @@ def get(self, var):
 
             sage: mathics.set('u', '2*x +E')        # optional - mathics
             sage: mathics.get('u')                  # optional - mathics
-            'E + 2 x'
+            '2 x + E'
         """
         return self.eval(var)
 
@@ -717,9 +720,9 @@ def _exponent_symbol(self):
 
             sage: bignum = mathics('10.^80')       # optional - mathics
             sage: repr(bignum)                     # optional - mathics
-            '1.*^80'
+            '1.×10^80'
             sage: repr(bignum).replace(mathics._exponent_symbol(), 'e').strip() # optional - mathics
-            '1.e80'
+            '1.×10^80'
         """
         return '*^'
 
@@ -772,34 +775,25 @@ def help(self, cmd, long=False):
         EXAMPLES::
 
             sage: mathics.help('Sin')                   # optional - mathics
-            "\n  'Sin[z]'\n    returns the sine of z.\n"
+            'sine function\n'
 
             sage: print(_)                              # optional - mathics
-            <BLANKLINE>
-            'Sin[z]'
-              returns the sine of z.
+            sine function
             <BLANKLINE>
 
             sage: print(mathics.help('Sin', long=True)) # optional - mathics
-            <BLANKLINE>
-              'Sin[z]'
-                returns the sine of z.
+            sine function
             <BLANKLINE>
             Attributes[Sin] = {Listable, NumericFunction, Protected}
             <BLANKLINE>
 
             sage: print(mathics.Factorial.__doc__)  # optional - mathics
-            <BLANKLINE>
-            'Factorial[n]'
-              'n!'
-              computes the factorial of n.
+            factorial
             <BLANKLINE>
 
             sage: u = mathics('Pi')                 # optional - mathics
             sage: print(u.Cos.__doc__)              # optional - mathics
-            <BLANKLINE>
-            'Cos[z]'
-              returns the cosine of z.
+            cosine function
             <BLANKLINE>
         """
         if long:
@@ -852,7 +846,7 @@ class MathicsElement(ExtraTabCompletion, InterfaceElement):
         sage: expr = res.last_eval; expr
         <Symbol: System`E>
         sage: type(expr)
-        <class 'mathics.core.expression.Symbol'>
+        <class 'mathics.core.symbols.Symbol'>
 
     Applying Mathics methods::
 
@@ -863,8 +857,6 @@ class MathicsElement(ExtraTabCompletion, InterfaceElement):
         'System`E'
         sage: me.is_inexact()
         False
-        sage: me.is_symbol()
-        True
 
     Conversion to Sage::
 

src/sage/libs/mpmath/ext_main.pyx

@@ -2135,6 +2135,9 @@ cdef class mpf(mpf_base):
         MPF_sqrt(&r.value, &s.value, global_opts)
         return r
 
+    def __round__(self, *args):
+        return round(float(self), *args)
+
     def __richcmp__(self, other, int op):
         """
         Compares numbers ::