[racket-dev] Wrapping loops for TR isn't working, and the type annotations are for the wrong value

----- Original Message -----
From: "Neil Toronto" <neil.toronto at gmail.com>
To: "Sam Tobin-Hochstadt" <samth at ccs.neu.edu>
Cc: "<dev at racket-lang.org>" <dev at racket-lang.org>
Sent: Wednesday, August 15, 2012 10:36:36 AM GMT -05:00 US/Canada Eastern
Subject: Re: [racket-dev] Wrapping loops for TR isn't working, and the type annotations are for the wrong value

On 08/15/2012 08:05 AM, Sam Tobin-Hochstadt wrote:
> On Wed, Aug 15, 2012 at 9:54 AM, Neil Toronto <neil.toronto at gmail.com> wrote:
>> When #:length is given, it's similar in that it creates a vector outside the
>> loop and bangs values into it. But I have to start with (define vs (vector))
>> and then (set! vs (make-vector n v)) when the first value `v' is computed.
>> The docs for `for/vector' say any values not computed in the loop are
>> supposed to be 0, but that doesn't work well in TR: it'd have to create a
>> (Vectorof (U T 0)). Ick.
>
> So then the first value computed is replicated everywhere?  That seems
> unappealing as well.

>It costs nothing, and if the #:length argument matches the number of 
>iterations, the user never sees it.

Not so, it costs memory leaks if the first value would otherwise be garbage collected.
-Ian

_________________________
  Racket Developers list:
  http://lists.racket-lang.org/dev