In [1]: import tangent
In [2]: import numpy as np
In [3]: def f(x):
...: return np.exp(x).sum() + 1
...:
...: df = tangent.grad(f)
...:
...:
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
<ipython-input-3-2246896ce926> in <module>()
2 return np.exp(x).sum() + 1
3
----> 4 df = tangent.grad(f)
~/workspace/tangent/tangent/grad_util.py in grad(func, wrt, optimized, preserve_result, check_dims, verbose)
386 check_dims=check_dims,
387 input_derivative=INPUT_DERIVATIVE.DefaultOne,
--> 388 verbose=verbose)
389
390
~/workspace/tangent/tangent/grad_util.py in autodiff(func, wrt, optimized, motion, mode, preserve_result, check_dims, input_derivative, verbose)
290 # Generate the derivative
291 node, namespace = autodiff_tree(func, wrt, motion, mode, preserve_result,
--> 292 check_dims, verbose)
293
294 if mode == 'reverse' and motion == 'joint':
~/workspace/tangent/tangent/grad_util.py in autodiff_tree(func, wrt, motion, mode, preserve_result, check_dims, verbose)
144
145 node, required = autodiff_ast(func, wrt, motion, mode, preserve_result,
--> 146 check_dims, verbose)
147 final.body.extend(node.body)
148
~/workspace/tangent/tangent/grad_util.py in autodiff_ast(func, wrt, motion, mode, preserve_result, check_dims, verbose)
88 for the returned function to run.
89 """
---> 90 node = annotate.resolve_calls(func)
91 node = desugar.explicit_loop_indexes(node)
92 fence.validate(node, inspect.getsource(func))
~/workspace/tangent/tangent/annotate.py in resolve_calls(func)
108 """
109 node = quoting.parse_function(func)
--> 110 ResolveCalls(func).visit(node)
111 return node
112
~/Software/miniconda/lib/python3.6/ast.py in visit(self, node)
251 method = 'visit_' + node.__class__.__name__
252 visitor = getattr(self, method, self.generic_visit)
--> 253 return visitor(node)
254
255 def generic_visit(self, node):
~/Software/miniconda/lib/python3.6/ast.py in generic_visit(self, node)
259 for item in value:
260 if isinstance(item, AST):
--> 261 self.visit(item)
262 elif isinstance(value, AST):
263 self.visit(value)
~/Software/miniconda/lib/python3.6/ast.py in visit(self, node)
251 method = 'visit_' + node.__class__.__name__
252 visitor = getattr(self, method, self.generic_visit)
--> 253 return visitor(node)
254
255 def generic_visit(self, node):
~/workspace/tangent/tangent/annotate.py in visit_FunctionDef(self, node)
43
44 def visit_FunctionDef(self, node):
---> 45 self.generic_visit(node)
46 anno.setanno(node, 'func', self.func)
47
~/Software/miniconda/lib/python3.6/ast.py in generic_visit(self, node)
259 for item in value:
260 if isinstance(item, AST):
--> 261 self.visit(item)
262 elif isinstance(value, AST):
263 self.visit(value)
~/Software/miniconda/lib/python3.6/ast.py in visit(self, node)
251 method = 'visit_' + node.__class__.__name__
252 visitor = getattr(self, method, self.generic_visit)
--> 253 return visitor(node)
254
255 def generic_visit(self, node):
~/Software/miniconda/lib/python3.6/ast.py in generic_visit(self, node)
261 self.visit(item)
262 elif isinstance(value, AST):
--> 263 self.visit(value)
264
265
~/Software/miniconda/lib/python3.6/ast.py in visit(self, node)
251 method = 'visit_' + node.__class__.__name__
252 visitor = getattr(self, method, self.generic_visit)
--> 253 return visitor(node)
254
255 def generic_visit(self, node):
~/Software/miniconda/lib/python3.6/ast.py in generic_visit(self, node)
261 self.visit(item)
262 elif isinstance(value, AST):
--> 263 self.visit(value)
264
265
~/Software/miniconda/lib/python3.6/ast.py in visit(self, node)
251 method = 'visit_' + node.__class__.__name__
252 visitor = getattr(self, method, self.generic_visit)
--> 253 return visitor(node)
254
255 def generic_visit(self, node):
~/workspace/tangent/tangent/annotate.py in visit_Call(self, node)
64 node.id, self.func.__name__))
65
---> 66 func = resolve(node.func)
67 # If the user has used the @tangent.trace decorator,
68 # then we'll switch to tracing the function.
~/workspace/tangent/tangent/annotate.py in resolve(node)
51 def resolve(node):
52 if isinstance(node, gast.Attribute):
---> 53 return getattr(resolve(node.value), node.attr)
54 if isinstance(node, gast.Name):
55 if node.id in self.namespace:
AttributeError: 'NoneType' object has no attribute 'sum'
I'm probably doing something silly here, but I was confused by this error: