Max Noel wrote:
On Feb 3, 2005, at 09:48, Alan Gauld wrote:
Pythons lambda feature is a bare minimum (and Guido wants to remove it!).
Does he? Damn, just when I was learning functional programming! (in Haskell, if you're curious ^^)
However, Python doesn't need lambdas to be able to write in a functional style. Functions are first-class objects and can be passed around quite easily, and IIRC Python's list comprehensions were borrowed (though probably with notable modification) from Haskell.
Keep in mind that both lambdas and named functions are created at runtime, so the creation of both is fully dynamic. Indeed, there are only a few differences between lambdas and named functions in Python:
- Anonymous vs named - Single expression vs suite of statements - Inline vs. pre-created
Note that the second of these is a consequence of the third -- given Python's block-indentation-based structure, there's no good way to inline a multi-statement suite (how many of those statements belong to that 'if' suite?). Statements need to have a clear indentation level, and while one can sometimes fudge that for a single statement, it gets exponentially messier as the number of statements goes up.
I'd also argue that the inline nature is the *true* differentiating feature of lambdas -- the fact that they're anonymous is relatively minor. Consider, also, that if they weren't inline then you'd need a name to refer to them by... and at that point, you *have* a 'normal' function.
So, while there are some advantages to having single-use callables be defined inline (i.e. lambdas), their removal from Python (which wouldn't happen before the mythical Python 3k anyhow) isn't likely to be as devastating as some might lead you to believe. ;) It certainly won't prevent you from using Python for functional programming...
(And personally, I suspect that if lambdas *are* removed, they will be replaced with a different construct that will fill the same needs in a more Pythonic way...)
Jeff Shannon Technician/Programmer Credit International
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