[racket] An error with dates and types

I still don't follow.  There's a shallow error -- 'ought' means the
same as 'should', presumably you mean to remove 'be able to' instead.
But there's also a deeper error, as far as I can tell.  In general,
one should use require rather than require/typed so you use a
binding's originally assigned type rather than assigning a new one.
One shouldn't use require for untyped bindings, but the problem here
is that Typed Racket blew up internally before it could report that
date->seconds is untyped.

Carl Eastlund

On Sun, Aug 21, 2011 at 1:47 PM, Matthias Felleisen
<matthias at ccs.neu.edu> wrote:
>
> I should have used 'ought' instead of 'should'.
>
> On Aug 21, 2011, at 1:38 PM, Carl Eastlund wrote:
>
>> Plain require works fine in Typed Racket; there's only a problem if TR
>> cannot typecheck the resulting code.  You normally only need to use
>> require/typed to assign types to otherwise-untyped imports.  The error
>> Norman reported looks like an internal error in TR related to the
>> contract on date->seconds.  Using require/typed is a workaround
>> because it avoids typechecking contract-wrapped references.
>>
>> Carl Eastlund
>>
>> On Sun, Aug 21, 2011 at 1:16 PM, Matthias Felleisen
>> <matthias at ccs.neu.edu> wrote:
>>>
>>> You shouldn't be able to use plain require in Typed Racket.
>>>
>>> Try this:
>>>
>>> #lang typed/racket
>>> (require/typed racket/date (date->seconds (date -> Natural)))
>>> (date->seconds (seconds->date (current-seconds)))
>>>
>>>
>>> On Aug 21, 2011, at 11:06 AM, Norman Gray wrote:
>>>
>>>>
>>>> Greetings.
>>>>
>>>> Another typed-racket problem, I'm afraid.
>>>>
>>>> With the following script, I get an error message from Typed Racket which is not, I think, really addressed to me.
>>>>
>>>> (Is the list generally OK for straight bug reports?  There isn't a bug parade I should be posting this on, is there?)
>>>>
>>>> All the best,
>>>>
>>>> Norman
>>>>
>>>>
>>>> % cat dates.rkt
>>>> #lang typed/racket
>>>> (require (only-in racket/date date->seconds))
>>>> (date->seconds (seconds->date (current-seconds)))
>>>> % "/Data/LocalApplications/Racket/5.1.3/bin/racket" dates.rkt
>>>> for: expected a sequence for i, got something else: (tc-results (list (tc-result Variable-Reference (#0=Top | #0#) -)) #f)
>>>>
>>>> === context ===
>>>> /Data/LocalApplications/Racket/5.1.3/collects/racket/private/for.rkt:445:2: make-sequence
>>>> /Data/LocalApplications/Racket/5.1.3/collects/typed-scheme/types/utils.rkt:103:2: ret
>>>> temp871
>>>> /Data/LocalApplications/Racket/5.1.3/collects/typed-scheme/typecheck/tc-expr-unit.rkt:201:4: loop
>>>> /Data/LocalApplications/Racket/5.1.3/collects/racket/private/map.rkt:18:11: map
>>>> parse-loop1141
>>>> /Data/LocalApplications/Racket/5.1.3/collects/typed-scheme/typecheck/tc-expr-unit.rkt:330:0: tc-expr
>>>> /Data/LocalApplications/Racket/5.1.3/collects/racket/private/map.rkt:18:11: map
>>>> temp971
>>>> /Data/LocalApplications/Racket/5.1.3/collects/typed-scheme/typecheck/tc-expr-unit.rkt:330:0: tc-expr
>>>> /Data/LocalApplications/Racket/5.1.3/collects/racket/private/map.rkt:18:11: map
>>>> temp971
>>>> /Data/LocalApplications/Racket/5.1.3/collects/typed-scheme/typecheck/tc-expr-unit.rkt:330:0: tc-expr
>>>> parse-loop26
>>>> dots-loop
>>>> /Data/LocalApplications/Racket/5.1.3/collects/racket/private/map.rkt:18:11: map
>>>> ...
>>>>
>>>> %
>>>>
>>>>
>>>> --
>>>> Norman Gray  :  http://nxg.me.uk
>>>> School of Physics and Astronomy, University of Glasgow, UK