subexpressions

[Peter Otten]

Sergey Dorofeev wrote:

> "Peter Otten" <__peter__ at web.de> wrote in message
> news:f3ok60$vp7$03$1 at news.t-online.com...
>> Sergey Dorofeev wrote:
>>
>>> Please help, is there way to use sub-expressions in lambda?
>>> For example, if I want to calculate sin(x^2)+cos(x^2) I must code:
>>> lambda x: sin(x*x)+cos(x*x)
>>> How to make x*x to be evaluated once?
>>
>>>>> (lambda x: [sin(x2) + cos(x2) for x2 in [x*x]][0])(.5) == sin(.5*.5) +
>> cos(.5*.5)
>> True
>>
>> The real answer is of course: Use a function.
> 
> But what about something like
> 
> lambda x: sin(y)+cos(y) where y=x*x
> 
> ?
> May be this could be a PEP? If there is no straight way to do this.

def f(x):
    y = x*x
    return sin(y) + cos(y)

What is not straightforward about that?

Peter