Lambda going out of fashion

[Nick Coghlan]

Alex Martelli wrote:
> Nick Coghlan <ncoghlan at iinet.net.au> wrote:
>    ...
> 
>>Perhaps something like:
>>
>>accepts_func( (def (a, b, c) to f(a) + o(b) - o(c)) )
> 
> 
> Nice, except I think 'as' would be better than 'to'.  'as' should be a
> full keyword in 3.0 anyway (rather than a surprisingly-NOT-keyword like
> today), and "define something as somethingelse" seems marginally more
> readable to me than "define something to somethingelse" anyway.

I actually flipped back and forth between preferring 'as' and 'to' while writing 
the message.

It was the mathematical phrasing of "f is a function from R to R" (replacing the 
capital R's with the symbol for the real numbers) that first made me think of 
'to', since I was trying to emphasise the parallels with mathematical functions. 
(To my mind, theoretical mathematics is one of the areas with significant 
legitimate uses for lambda functions).

The '->' suggestion had a similar source.

The way I'd read the 'to' version out loud when explaining to someone what the 
code did:

"DEFine an anonymous function from arguments a, b and c TO the value f of a plus 
o of b minus o of c"

or the short version:

"DEFine a function from a, b and c TO f a plus o b minus o c"

As an even simpler example, (def (x) to x * x) would be "define a function from 
x to x squared". (def () to <whatever>) would be "define a function from no 
arguments to <whatever>"

'as' already implies renaming semantics due to from-style imports. In Py3k, it's 
likely to pick up the naming duties in except clauses as well (i.e. "except 
ValueError, TypeError as ex:").

'as' is also a candidate for optional static typing and adaptation (and 
hopefully someone will talk Guido out of his punctuation happy version of that!).

I eventually decided that using 'as' for anonymous functions as well would just 
be plain confusing.

Cheers,
Nick.

-- 
Nick Coghlan   |   ncoghlan at email.com   |   Brisbane, Australia
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