[Python-Dev] Shorthand for lambda

[Hye-Shik Chang]

On Wed, 23 Mar 2005 10:33:53 -0600 (CST), Ka-Ping Yee
<python-dev at zesty.ca> wrote:
> Hey folks,
> 
>     >>> from placeholder import _
>     >>> numbers = [5, 9, 56, 34, 1, 24, 37, 89]
>     >>> filter(_ < 30, numbers)
>     [5, 9, 1, 24]
>     >>> map(_ + 10, numbers)
>     [15, 19, 66, 44, 11, 34, 47, 99]
>     >>>
> 
> Look ma, no lambdas!
> 
> I bet someone has already done this before, right?
> 

I tried it once before:
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/local-distfiles/perky/anonfunc-1.0.tar.gz

>>> from anonfunc import *
>>> f = (arg0 * arg1 + 3 * arg2) ** 2
>>> f(5, 6, 7)
2601

>>> f = kw1 and kw2
>>> f(kw1=False, kw2=True)
True
>>> f(kw2=False, kw1=True)
False

But there were some serious drawbacks to use it instead of lambda.

 * (a,b,c) is impossible
 * unable to use it with list comprehensions and generator expressions
 * can't call functions and use its return value
 * and many builtin functions as you described (such as len(), sorted())


Hye-Shik