On 4/19/2012 8:12 AM, lkcl luke wrote:
you don't *have* to use lambdas with map and reduce, you just have touse a function,
> where a lambda happens to be a nameless function.
Abbreviated statements like the above sometimes lead people to think that there is more difference between def functions and lambda functions than there is, at least in Python.
The word 'lambda' is used ambiguously by various people for either the expression or the resulting object -- or perhaps even for both. You clearly mean the function object above, but other are not so clear.
The word 'nameless' is also ambiguous in that it could refer to the syntax construct, a name attribute, or a namespace binding. Lambda expressions are nameless, but the resulting function objects are not. Lambda expressions and def statements both produce function objects with a .__name__ attribute. For lambda functions, .__name__ is always '<lambda>'. So to be exact, a lambda function, resulting from a lambda expression, is a function with the default name '<lambda>'.
As for name binding: a lambda function can be explicitly bound to a name in any namespace, just like any other object. The automatic local namespace binding of a def function can be explicitly undone, just like any other binding. So any function, regardless of creation syntax, can be named or not in any namespace, just like any other object.
-- Terry Jan Reedy -- http://mail.python.org/mailman/listinfo/python-list
