2.1 Functions as first-class objects
Functional programming is often succinct and expressive. One way to achieve this is by providing functions as arguments and return values for other functions. We’ll look at numerous examples of manipulating functions.
For this to work, functions must be first-class objects in the runtime environment. In programming languages such as C, a function is not a runtime object; because the compiled C code generally lacks internal attributes and methods, there’s little runtime introspection that can be performed on a function. In Python, however, functions are objects that are created (usually) by def statements and can be manipulated by other Python functions. We can also create a function as a callable object or by assigning a lambda object to a variable.
Here’s how a function definition creates an object with attributes:
>>> def example(a, b, **kw):
... return a*b
...
>>> type(example) ...
