# [racket] function equality with contracts

 From: Eric Tanter (etanter at dcc.uchile.cl) Date: Mon Jan 24 16:44:08 EST 2011 Previous message: [racket] function equality with contracts Next message: [racket] Exercise 3.1 HTDP Help Messages sorted by: [date] [thread] [subject] [author]

```Just tried my example on 5.0.99.6 and it indeed works.

That was just in time!

-- Éric

On Jan 24, 2011, at 6:35 PM, Eric Tanter wrote:

> Great, that's a much happier reply than your previous one, indeed :-)
>
> Thanks!!
>
> -- Éric
>
>
> On Jan 24, 2011, at 6:33 PM, Robby Findler wrote:
>
>> change to the contract system (that I helped with a little bit but
>> that Stevie and Matthew did most of the work for).
>>
>> If you change eqv? in your code to equal?, you should get #t back.
>> You'll need the pre-release version, tho. This was no in 5.0.2.
>>
>> Sorry,
>> Robby
>>
>> On Mon, Jan 24, 2011 at 3:15 PM, Eric Tanter <etanter at dcc.uchile.cl> wrote:
>>> Sorry, I don't get it. I'm not asking from a theoretical point of view, but from a very practical, racket point of view, of two functions being eqv.
>>>
>>> Concretely:
>>> ;; tmp.rkt
>>> #lang racket
>>> (define f (λ (x) x))
>>> (define ((pred f1) f2) (eqv? f1 f2))
>>> (define eq-f (pred f))
>>> (provide/contract [f (-> integer? integer?)])
>>> (provide eq-f)
>>>
>>> ;;tmp2.rkt
>>> #lang racket
>>> (require "tmp.rkt")
>>> (eq-f f)
>>>
>>> -> is there a way to get that last call return #t?
>>>
>>> -- Éric
>>>
>>> On Jan 24, 2011, at 5:56 PM, Matthias Felleisen wrote:
>>>> On Jan 24, 2011, at 2:41 PM, Eric Tanter wrote:
>>>>> Hi all,
>>>>>
>>>>> From the DLS'10 paper of Stephen and Matthias, it says "the class system must determine that two classes are equal modulo contract wrapping".
>>>>>
>>>>> I'm interested in that exact property but for functions. Ie. how do we determine if two functions are "equal" modulo contract wrapping?
>>>>
>>>> eta-expansion? proxy-lambda?
>>>>
>>>>
>>>>>
>>>>> Thanks!
>>>>>
>>>>> -- Éric
>>>>> _________________________________________________
>>>>> http://lists.racket-lang.org/listinfo/users
>>>>
>>>>
>>>
>>> _________________________________________________