Op 26-11-15 om 16:36 schreef Marko Rauhamaa: > Antoon Pardon <antoon.par...@rece.vub.ac.be>: > >> [ <expression> for <var> in <iter> ] >> >> would implicitly be rewritten as follows: >> >> [ (lambda <var>: <expression>)(<var>) for <var> in <iter>] > > Funny enough, that's how "list comprehensions" are created in Scheme: > > (map (lambda (i) > (lambda (x) (* i x))) > '(0 1 2 3)))) > >> There would no change on how lambdas work or functions or closures. > > First of all, it's weird to spend any effort in trying to alter a very > special case.
<shrug> Maybe it is small enough an effort but I wont loose any sleep over it should the dev team have other priorities. > I don't recall having to generate a list of such > functions. In fact, I barely ever use lambda in Python; explicit def > statements are much more pleasing to the eye and are not restricted to > simple expressions. > > Secondly, you'd lose the nice symmetry between for statements and > comprehensions/generators. For example: > > ( lambda x: i * x for i in range(4) ) > > corresponds to: > > for i in range(4): > yield lambda x: i * x > > Would you embed an extra lambda there, too? No, not because that would be so troublesome in semantics but because it would be annoying in python. Because in that case you would embed a function (call) or introduce an intermediate scope. Which would mean that if you want to rebind a variable within the suite of the for loop that is also used in other parts of the function/modules you would have to declare that variable nonlocal/global at the start of the suite. So it would be annoying plus that it would be difficult to explain to people new to the language. Such an embedding would only be practical in a language where you have to declare your variables. -- Antoon. -- https://mail.python.org/mailman/listinfo/python-list
