There was an extensive discussion about this in the past.
In the end Guido felt that his effort seems to him like building a Rube Goldberg machine.
By looking at the amount of people still stumbling on this issue we definitely feel, that it is not
the. Such a machine is a useful one.
"Naming things" was from the beginning one the two hardest things in programming. Good naming is important for understandable code. The balance of extracted, named functions, as most of things in programming, is subjective though.
The python style guide itself encourages people to use simple data transformations like `map`, `filter`, `reduce` for expressiveness. Those transformations can still be simple with 2 or 3 statements and will not require naming. Naming the transformation becomes harder, than reading the actual code.
Coffeescript, which is another indent based language, handles multi statement lambdas
without curly braces.
arr = []
arr.map((x)->
y = x+1
y * 2
)
There is also an argument in this discussion, that just using curly braces for lambdas (which is easier to implement) would be pretty unpythonic.
I really agree that python curly braces free block style is really helpful for readability in contrast to javascript for example. However using curly braces for lambdas in ruby is not hurting the eyes that much. Normally blocks in ruby use `do .. end` notation. Thus lambdas are clearly visible and also people try not to nest multiple levels of lamda transfromations. We strive to keep such a chain flat.
def transform
arr
.map { ... }
.filter { ... }
.reduce { ... }
In the end curly branes for lambdas is also a mathematical notation.
Guido had a hard opinion on this, but i hope the python community does not. A powerful general purpose language should not limit itself to one statement in a closure.
Lets add mutli-statement lambdas to python either with just curly braces or with an indent based machine.