[Python-ideas] Thoughts on lambda expressions

[Ethan Furman]

On 03/02/2016 12:01 PM, Abe Dillon wrote:

> More generally, I think a superior syntax for lambda would be:
>
> (<expression> from <signature>)
>
> The reasons I believe that's a superior syntax are:
>
> a) In the vast majority of use cases for lambda expressions the call
> signature can be easily inferred (like in a key function), so moving it
> after the expression tends to be more readable.

And what does it look like when you have more than one paramater in the 
signature and/or something beside simple attribute lookup?

   'open': lambda s, cr, uid, rec, ctx: rec['state'] == 'draft',

would instead be:

   'open': rec['state'] == 'draft' from (s, cr, uid, rec, ctx),

Ouch.  That just went from bad to horrid.

> b) It doesn't use the esoteric name, 'lambda' which causes its own
> readability issues.

On the contrary:  'lambda' lets you know immediately what you're dealing 
with.  The syntax you are suggesting looks like:

- a (wrong) generator
- taking ... items? ... from some kind of container

To be fair, it looked like an interesting syntax at first glance, but 
deeper investigation shows serious drawbacks.

--
~Ethan~