[plt-scheme] redex: recursive metafunctions

On May 2, 2009, at 13:17 , Robby Findler wrote:
> Well, the contract is written on the metafunction and since there are
> no HO contracts, I didn't include that in the error message (altho if
> you still think it would help, I could).

I think so, yes.

> But as for the other, that is what you got. The function was called  
> like this:
>
>   (collect-d)

I don't get this. It rather seems to me that the function was called  
1+ arguments
(the triple (x_1 v_1 s_1) and the "...")

-- Éric

> On Sat, May 2, 2009 at 11:34 AM, Eric Tanter <etanter at dcc.uchile.cl>  
> wrote:
>>>> I get an error "collect-d: (collect-d) is not in my domain"
>>>>
>>>> The defintion of collect-d is:
>>>>
>>>> (define-metafunction λenv
>>>>  collect-d : (env (x v s) ...) -> (env (x v s) ...)
>>>>  ((collect-d (env)) (env))
>>>>  ((collect-d (env (x_0 v_0 (b_0 true)) (x_1 v_1 s_1) ...))
>>>>  (env-append (env (x_0 v_0 (b_0 true))) (collect-d (x_1 v_1  
>>>> s_1) ...)))
>>>
>>> The recursive call just above looks like it is missing "(env ..)"
>>> around its argument.
>>
>> Just wondering: since the contract of the metafunction is clear,  
>> couldn't it
>> be possible to report more precisely what the problem is (similarly  
>> to
>> contract violations), something along the lines of:
>> "collect-d broken contract: expected (env (x v s) ...) given (x v  
>> s) (other
>> arguments were ...)"
>>
>> ?
>>
>> -- Éric