On Tue, 23 Feb 2021 at 15:52, M.-A. Lemburg <m...@egenix.com> wrote: > > On 23.02.2021 15:29, Paul Moore wrote: > > On Tue, 23 Feb 2021 at 14:10, M.-A. Lemburg <m...@egenix.com> wrote: > >> > >> The natural way in Python to write an anonymous function would > >> be to simply drop the name in a regular function definition: > >> > >> def (a): return a**2 > >> > >> The lambda notation is less verbose and closer to computer > >> science theory, though: > >> > >> lambda a: a**2 > >> > >> FWIW: I don't understand why people are so unhappy with lambdas. > >> There isn't all that much use for lambdas in Python anyway. Most > >> of the time, a named function will result in more readable code. > > > > Typically because they are simple expressions like the a**2 you used above. > > > > def a_squared(a): > > return a**2 > > > > is way over the top. > > Fair enough. Although as soon as you use the same such function > more than once in your application, giving it a name does make > sense :-) > > > Thinking about it, maybe the *real* solution here is to use one of the > > "placeholder variable" libraries on PyPI - there's "placeholder" which > > I found on a quick search: > > > > from placeholder import _ # single underscore > > > > _.age < 18 # lambda obj: obj.age < 18 > > _[key] ** 2 # lambda obj: obj[key] ** 2 > > > > Some people will hate this sort of thing - probably the same people > > who can't see why anyone has a problem with lambda - but it doesn't > > need a language change, and it's available now. > > > > I guess I've convinced myself here - we already have shorter > > alternatives to lambda, so why add a new built-in one? > > People should have a look at the operator module. It's full of > short (and fast) functions for many things you often write > lambdas for: > > https://docs.python.org/3/library/operator.html
Definitely. But in cases like this (where brevity and matching the form of an expression is considered important) `partial(add, 2)` doesn't really compare to `lambda x: x+2` (or `x -> x+2`, or `_+2` if you like placeholders). And even using functools.partial, the operator module won't be able to replace `lambda x: x*x` (you can't even transform it to `x**2` and use partial, because the constant is the right hand argument). It's all very subjective, of course. Paul _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/QHFAJGNSV5FMOAF52SDBQ4EN3MY6LJG2/ Code of Conduct: http://python.org/psf/codeofconduct/
