Multi-line lambda proposal.

[nikie]

Kaz Kylheku wrote:

> Kaz Kylheku wrote:
> > But suppose that the expression and the multi-line lambda body are
> > reordered? That is to say, the expression is written normally, and the
> > mlambda expressions in it serve as /markers/ indicating that body
> > material follows. This results in the most Python-like solution.
>
> Unfortunately, while this idea has intuitive appeal,

It does? Didn't seem so in the responses you got so far, did it... ;-)
SCNR

> it leaves some
> problems to solve; namely, lambdas that occur in expressions embedded
> within statement syntax which has body material of its own. For
> instance
>
>   # lambda defined and immediately called here
>   if lambda(x)(4) < 0:
>      print "a"
>   elif y = 4:
>      print "b"
>   else:
>      print "foo"
>
> Where to stick the lambda body? It's not hard to come up with
> straightforward answers, except that they are not particularly
> appealing. One rule might be that the lambda bodies have to be placed
> immediately after the statement body material, set off by the lambda:
> thing. In the case of if/elif/else, they have to be placed behind the
> closest suite that follows the expression in the syntax of the
> statement:
>
>   if lambda(x)(4) < 0:
>      print "a"
>   lambda:
>      return x + 1
>   elif y = 4:
>      print "b"
>   else:
>      print "foo"
>
> The overall rule is simple and uniform: each suite can have lambda:
> clauses. These have to match lambda() occurences in the expression (or
> expression list) immediately to the left in the same grammar
> production.

Sorry to tell you this, but I think that kind of thing is exactly what
the BDFL had in mind when he talked about "Rube-Goldberg-Devices" in
Python...