[racket-dev] [plt] Push #21701: master branch updated

On Fri, Dec 10, 2010 at 8:26 AM, Casey Klein
<clklein at eecs.northwestern.edu> wrote:
> On Fri, Dec 10, 2010 at 7:00 AM, Eli Barzilay <eli at barzilay.org> wrote:
>>
>> As for a suggestion, I don't have anything concrete (and I don't have
>> nearly enough contract experience to say something concrete) -- but in
>> general I prefer to see those important bits first, and the vague
>> human text later.
>>
>
> This organization was my goal in suggesting that we tack an
> explanation onto the old message. I was imagining something like this:
>
> /Users/clklein/tmp/contract-violator.rkt:9.17:
>  (file /Users/clklein/tmp/contract-violator.rkt)
>  broke the contract (-> any/c any/c any/c) on #:equiv argument of
> test-->; expected a procedure that accepts 2 mandatory arguments
> without any keywords, given: 1. Possible fixes include changing (file
> /Users/clklein/tmp/contract-violator.rkt) and changing the contract.

I like the idea of better error messages, and in that spirit, I
suggest: newlines.

For example:

/Users/clklein/tmp/contract-violator.rkt:9.17: (file
/Users/clklein/tmp/contract-violator.rkt) broke the contract (-> any/c
any/c any/c) on #:equiv argument of test-->:
   Expected: a procedure that accepts 2 mandatory arguments without
any keywords.
   Given: 1.
   Possible fixes include changing (file
/Users/clklein/tmp/contract-violator.rkt) and changing the contract.

For an effective use of text formatting in error messages, the GHC
type error messages are good examples.
-- 
sam th
samth at ccs.neu.edu