How to check that variable is a lambda function

You need to use types.LambdaType or types.FunctionType to make sure that the object is a function object like this

x = lambda d:d*d
import types
print type(x) is types.LambdaType
# True
print isinstance(x, types.LambdaType)
# True

and then you need to check the name as well to make sure that we are dealing with a lambda function, like this

x = lambda x: None
def y(): pass
print y.__name__
# y
print x.__name__
# <lambda>

So, we put together both these checks like this

def is_lambda_function(obj):
    return isinstance(obj, types.LambdaType) and obj.__name__ == "<lambda>"

As @Blckknght suggests, if you want to check if the object is just a callable object, then you can use the builtin callable function.

If you prefer the typing module, use Callable:

In [1]: from typing import Callable
In [2]: isinstance(lambda: None, Callable)
Out[2]: True

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