Support for Python array API standard

opt_einsum/backends/array_api.py

@@ -40,23 +40,26 @@ def to_array(array): # pragma: no cover
 
 def make_build_expression_function(array_api: ModuleType) -> Callable:
  """Make a ``build_expression`` function for the given array API."""
+ _to_array_api = to_array_api[array_api.__name__]
 
  def build_expression(_, expr): # pragma: no cover
  """Build an array API function based on ``arrays`` and ``expr``."""
 
  def array_api_contract(*arrays):
- return expr._contract([make_to_array_function(array_api)(x) for x in arrays], backend=array_api.__name__)
+ return expr._contract([_to_array_api(x) for x in arrays], backend=array_api.__name__)
 
  return array_api_contract
 
  return build_expression
 
 
 def make_evaluate_constants_function(array_api: ModuleType) -> Callable:
+ _to_array_api = to_array_api[array_api.__name__]
+
  def evaluate_constants(const_arrays, expr): # pragma: no cover
  """Convert constant arguments to cupy arrays, and perform any possible constant contractions."""
  return expr(
- *[make_to_array_function(array_api)(x) for x in const_arrays],
+ *[_to_array_api(x) for x in const_arrays],
  backend=array_api.__name__,
  evaluate_constants=True,
  )