Add linters

.flake8

@@ -0,0 +1,8 @@
+[flake8]
+doctests = True
+ignore =
+    F403,
+select =
+    C4,
+    E722,
+    F,

.github/workflows/runtests.yml

@@ -0,0 +1,32 @@
+# ------------------------------------------------------------------ #
+#                                                                    #
+#           SymPy Benchmark CI script for Github Actions             #
+#                                                                    #
+#   Runs each time a pull request is opened, pushed or merged        #
+#                                                                    #
+# ------------------------------------------------------------------ #
+
+name: test
+on: [push, pull_request]
+jobs:
+
+  # -------------------- Code quality ------------------------------ #
+
+  code-quality:
+
+    runs-on: ubuntu-20.04
+    steps:
+      - uses: actions/checkout@v3
+
+      - uses: actions/setup-python@v4
+        with:
+          python-version: '3.11'
+      - run: python -m pip install --upgrade pip
+
+      - run: pip install flake8 ruff
+
+      - name: Run flake8 on the sympy benchmark package
+        run: flake8 benchmarks slow_benchmarks
+
+      - name: Run Ruff on the sympy benchmark package
+        run: ruff check .

benchmarks/cse.py

@@ -3,7 +3,10 @@
 from functools import reduce
 from operator import add
 
-from sympy import cse, exp, sin, symbols, tan, Matrix
+import sympy as sym
+from sympy import cse, exp, sin, symbols, tan, Matrix, ImmutableDenseMatrix, MatAdd, MatMul, Transpose, Inverse, \
+    MatrixSymbol
+from sympy.core.singleton import SingletonRegistry
 
 
 def _get_args_exprs(nexprs, nterms):
@@ -239,6 +242,9 @@ def time_combined_cse(self):
         cse([self.y, self.G])
 
 
+S = SingletonRegistry()
+
+
 class KalmanFilterMatrixEquationCSE:
     """Kalman filter example from Matthew Rocklin's SciPy 2013 talk.
 

benchmarks/dsolve.py

@@ -1,6 +1,5 @@
 # -*- coding: utf-8 -*-
 
-import sympy
 from sympy import symbols, dsolve, Eq, Function, exp
 
 def _make_ode_01():

benchmarks/matrices.py

@@ -96,10 +96,10 @@ class TimeMatrixPower:
             [     1/4 + 13*I/4,    -825/64 - 147*I/32,          21/8 + I,    -537/64 + 143*I/16,    -5/8 - 39*I/16,   2473/256 + 137*I/64,    -149/64 + 49*I/32,   -177/128 - 1369*I/128]]'''))
 
     def time_Case1(self):
-        m = self.Case1**4
+        _ = self.Case1**4
 
     def time_Case2(self):
-        m = self.Case2**4
+        _ = self.Case2**4
 
     def time_Case3(self):
-        m = self.Case3**4
+        _ = self.Case3**4

benchmarks/solve.py

@@ -179,7 +179,7 @@ def time_solve_lin_sys(self):
 
     def time_verify_sol(self):
         zeros = [eq.compose(self.sol) for eq in self.eqs]
-        if not all([zero == 0 for zero in zeros]):
+        if not all(zero == 0 for zero in zeros):
             raise ValueError("All values in zero should be 0")
 
     def time_to_expr_eqs(self):

benchmarks/solve_large_poly.py

@@ -3,7 +3,6 @@
 from sympy.polys.rings import ring
 from sympy.polys.fields import field
 from sympy.polys.domains import ZZ, QQ
-from sympy.polys.solvers import solve_lin_sys
 
 # Expected times on 3.4 GHz i7:
 

benchmarks/sum.py

@@ -3,7 +3,6 @@
 The evalutation of symbolic sum via the doit method got slowed by the introdution of Piecewise. Simple profiling suggest that piecewise_fold is taking up to 97% of the time.
 It worked much faster on 0.7.2(3) than on 1.0.
 """
-import sympy
 from sympy import symbols, Function, Sum, I, Symbol, KroneckerDelta
 
 int12Sigma, int22Sigma, exgg12SU2L, intgg11SU2L, intgg11SU2L, ext12Sigma, ext11Sigma, ext11Sigma, exgg22SU2L, intgg11SU2L, intgg11SU2L, ext22Sigma, ext31Sigma, ext31Sigma, exgg32SU2L, intgg21SU2L, intgg21SU2L, ext32Sigma, ext21Sigma, ext21Sigma, exgg42SU2L, intgg21SU2L, intgg21SU2L, ext42Sigma, ext41Sigma, ext41Sigma, int32ASU2L, int42ASU2L, int52ASU2L,  int62ASU2L, ext12Pi, ext11Pi, ext11Pi, exgg22SU2L, intgg11SU2L, intg11SU2L, ext22Pi, ext41Pi, int12Pi, int22Pi, ext32Pi, int62ASU2L, ext42Pi, exgg12SU2L, exgg32SU2L, intgg21SU2L, ext31Pi, exgg42SU2L, intgg21SU2L, intgg21SU2L, ext42Pi, ext21Pi, ext21Pi = symbols('int12Sigma int22Sigma exgg12SU2L intgg11SU2L intgg11SU2L ext12Sigma ext11Sigma ext11Sigma exgg22SU2L intgg11SU2L intgg11SU2L ext22Sigma ext31Sigma ext31Sigma exgg32SU2L intgg21SU2L intgg21SU2L ext32Sigma ext21Sigma ext21Sigma exgg42SU2L intgg21SU2L intgg21SU2L ext42Sigma ext41Sigma ext41Sigma int32ASU2L int42ASU2L int52ASU2L  int62ASU2L ext12Pi ext11Pi ext11Pi exgg22SU2L intgg11SU2L intg11SU2L ext22Pi ext41Pi int12Pi int22Pi ext32Pi int62ASU2L ext42Pi exgg12SU2L exgg32SU2L intgg21SU2L ext31Pi exgg42SU2L intgg21SU2L intgg21SU2L ext42Pi ext21Pi ext21Pi')

pyproject.toml

@@ -0,0 +1,44 @@
+[tool.ruff]
+# Enable Pyflakes `E` and `F` codes by default.
+select = [
+    "C40",
+    "E",
+    "F",
+    "PIE802",
+    "PIE810",
+    "SIM101",
+]
+
+# Ignore rules that currently fail on the SymPy codebase
+ignore = [
+    "E401",  # Multiple imports on one line
+    "E402",  # Module level import not at top of file
+    "E501",  # Line too long (<LENGTH> > 88 characters)
+    "E701",  # Multiple statements on one line (colon)
+    "E702",  # Multiple statements on one line (semicolon)
+    "E703",  # Statement ends with an unnecessary semicolon
+    "E711",  # Comparison to `None` should be `cond is not None`
+    "E712",  # Comparison to `<BOOL>` should be `cond is <BOOL>`
+    "E713",  # Test for membership should be `not in`
+    "E714",  # Test for object identity should be `is not`
+    "E721",  # Do not compare types, use `isinstance()`
+    "E722",  # Do not use bare `except`
+    "E731",  # Do not assign a `lambda` expression, use a `def`
+    "E741",  # Ambiguous variable name: `<VARIABLE>`
+    "E743",  # Ambiguous function name: `<FUNCTION>`
+    "F401",  # `<TYPE>` imported but unused
+    "F403",  # `from <MODULE> import *` used; unable to detect undefined names
+    "F405",  # `<TYPE>` may be undefined, or defined from star imports: `<MODULE>`
+    "F523",  # `.format` call has unused arguments at position(s): <INDEX>
+    "F601",  # Dictionary key literal `'<KEY>'` repeated
+    "F811",  # Redefinition of unused `<VARIABLE>` from line <LINE>
+    "F821",  # Undefined name `VARIABLE`
+    "F823",  # Local variable `VARIABLE` referenced before assignment
+    "F841",  # Local variable `VARIABLE` is assigned to but never used
+]
+
+# Black default, although irrelevant with E501 ignored
+line-length = 88
+
+# Allow unused variables when underscore-prefixed.
+dummy-variable-rgx = "^(_+|(_+[a-zA-Z0-9_]*[a-zA-Z0-9]+?))$"

slow_benchmarks/matrices.py

@@ -1,5 +1,5 @@
-from sympy import Symbol, Matrix, symbols, SparseMatrix, Abs
-from sympy import I, S, simplify
+from sympy import Matrix, symbols, SparseMatrix
+from sympy import S
 from sympy.simplify.simplify import simplify
 
 _TEST_SIMPLIFY = False # test simplify after operation?

slow_benchmarks/solve.py

@@ -1,7 +1,5 @@
 # -*- coding: utf-8 -*-
 
-import sympy
-
 class TimeMatrixOperations:
     # first param is the size of the matrix, second is the number of symbols in it
     params = ((6,10), (0, 2, 5))

slow_benchmarks/tests/test_refine.py

@@ -1,7 +1,7 @@
 from __future__ import absolute_import
 
 import sympy
-from sympy import dsolve, Eq, exp, refine
+from sympy import Eq, exp, refine
 
 from slow_benchmarks.refine import _mk_piecewise_01