[racket-dev] [plt] Push #24906: master branch updated

From: Ryan Culpepper (ryan at cs.utah.edu)
Date: Mon Jun 25 22:17:33 EDT 2012

On 06/25/2012 06:57 PM, Asumu Takikawa wrote:
> On 2012-06-25 20:35:21 -0400, asumu at racket-lang.org wrote:
>> | racket/generics: add contract combinator
>> |
>> | The generics library now generates a `name/c` macro
>> | for a generic interface `name`. The combinator can be
>> | used to contract instances (or constructors) of a
>> | generic interface across standard contract boundaries.
> To add a bit more context, the purpose of this feature is to allow
> contracts to be applied to generic interfaces like how
> `prop:dict/contract` does for dictionaries.
> It's more flexible because it allows contracts to be added for any
> interface (without any additional properties) and allows contracts
> to be added at different places. e.g., you could export
> `make-prime-dict` and `make-dict` constructors with different
> contracts.
> If nobody minds, I may go ahead and convert uses of `prop:dict/contract`
> to use `dict/c` and export the latter from `racket/dict`.

IIUC from your later message, you've implemented the generics analogue 
of object/c (per-instance contract), whereas prop:dict/contract is 
closer to class/c (per-type contract). It's a little fuzzy because 
prop:dict/contract hacks in per-instance contracts too in a kind of ad 
hoc way.


Posted on the dev mailing list.