[racket-dev] Code micro-level organization

How about a define* that is exactly like let* without the additional
indentation level?
E.g.:

(define*
[↑ "foo bar baz"]
[↑ (substring ↑ 3 8)]
[str (string-trim ↑)]
[↑ (regexp-match? #rx"^[a-z].*[a-z]$" str)])
(and ↑ (string-append "*" str "*"))

Laurent

Le 31 mai 2012 19:04, "Neil Toronto" <neil.toronto at gmail.com> a écrit :
>
> On 05/30/2012 03:40 PM, Eli Barzilay wrote:
>>
>> Now, lets imagine that instead of a simple `<>' hole, there are two
>> kinds of holes with an "up" or a "down" direction -- this leads to
>> this kind of a syntax:
>>
>>   (○ "foo bar baz"
>>      (substring ↑ 3 8)
>>      (string-trim ↑)
>>      (let ([str ↑]) ↓)
>>      (and (regexp-match? #rx"^[a-z].*[a-z]$" str) ↓)
>>      (string-append "*" str "*"))
>>
>> where you can read `↑' as "the above" and `↓' as "the below".
>
>
> It seems like `↑' is another way to not name expressions (i.e. a
"pointless style" :D), and `↓' is handled just fine by internal
definitions. This is equivalent, currently defined, has less nesting, and
avoids a rename:
>
>   (define orig-str "foo bar baz")
>   (define sub (substring orig-str 3 8))
>   (define str (string-trim sub))
>   (define m (regexp-match? #rx"^[a-z].*[a-z]$" str))
>   (and m (string-append "*" str "*"))
>
> A `define*' form like Jay (and I) want would make these kinds of things
less error-prone and allow names to be reused:
>
>   (define* ↑ "foo bar baz")
>   (define* ↑ (substring ↑ 3 8))
>   (define* str (string-trim ↑))
>   (define* ↑ (regexp-match? #rx"^[a-z].*[a-z]$" str))
>   (and ↑ (string-append "*" str "*"))
>
> It's still pretty wordy, though. Even if I had `define*' I'd be tempted
to go with my current favorite idiom, which trades wordiness for a nesting
level:
>
> (let* ([↑    "foo bar baz"]
>       [↑    (substring ↑ 3 8)]
>       [str  (string-trim ↑)]
>       [↑    (regexp-match? #rx"^[a-z].*[a-z]$" str)])
>  (and ↑ (string-append "*" str "*")))
>
> I occasionally get annoyed by how deeply these can get nested. I feel
your pain, man.
>
> Neil ⊥
>
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