[Python-ideas] Multi Statement Lambdas

[Ron Reiter]

Multi-line lambdas may be nice for functional languages, but Python is very
imperative in nature and prefers clean syntax over conciseness, which means
it will make it REALLY hard to fit with Python. I personally find
multi-line lambdas an unreadable abomination.

As for some more concrete reasons on why this should not be a part of
Python, see here for an example which shows why it would even be hard to
come up with a plausible syntax for multi-line lambdas:
https://stackoverflow.com/questions/1233448/no-multiline-lambda-in-python-why-not

Guido's words:

"But the complexity of any proposed solution for this puzzle is immense, to
me: it requires the parser (or more precisely, the lexer) to be able to
switch back and forth between indent-sensitive and indent-insensitive
modes, keeping a stack of previous modes and indentation level. Technically
that can all be solved (there's already a stack of indentation levels that
could be generalized). But none of that takes away my gut feeling that it
is all an elaborate Rube Goldberg contraption."

If one would find a syntax which is Pythonic and clean then I am in favor
of adding it, but I argue it simply does not exist.

- Ron


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On Sun, Oct 21, 2018 at 7:34 PM Anders Hovmöller <boxed at killingar.net>
wrote:

>
> Wheres a lambda expression can be passed anonymously to any other function
> as an argument.
>
> *map(lambda x: x**2, array)*
>
> vs
>
> *def powers2(x)*
> *   x**2*
> *map(powers2, array)*
>
> Coming up with a name here is not needed, as the operation is expressive
> enough.
>
>
> Sure, but there is a well known convention for such non-names already:
> meta syntactical variables. In this case the name could be "foo" and all
> readers will interpret this as "no name".
>
> I admit to have wanted lambdas that are just as powerful as normal
> functions, but often when I want it the code is nicer when a normal
> function is used.
>
> / Anders
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