[Ur] Unification Problems

[David Snider]

My user.urs file has:

val main : unit -> transaction page


On 10/21/2012 06:16 PM, Adam Chlipala wrote:
> That didn't turn out to be it.  Your [main] function is ambiguous; 
> it's not obvious from the code there now that it returns standalone 
> pages.  You can use type annotations in your .ur file to indicate the 
> type, but it would be better to create a .urs file declaring [main] as 
> in most of the demos.
>
> On 10/21/2012 05:55 PM, David Snider wrote:
>> Ah, OK...
>>
>> Here is the whole source:
>> http://pastebin.com/EZMqZVkd
>>
>> Is it that it can't decide whether to take it from the User table 
>> record or the cookie record?
>>
>> On 10/21/2012 05:42 PM, Adam Chlipala wrote:
>>> I need more context to give a complete answer.  The error message 
>>> means that some type is not uniquely determined, and the message 
>>> will show you where the undetermined type appears.
>>>
>>> My first guess, though: Start the function declaration like this:
>>>     fun checkPassword (r : {Email : string, Password : string}) =
>>>
>>> Otherwise, there might be other fields in [r].
>>>
>>> On 10/21/2012 05:39 PM, David Snider wrote:
>>>> What's the correct way of doing this?
>>>>
>>>> Error: Some constructor unification variables are undetermined in 
>>>> declaration
>>>>
>>>> cookie userSession : { Email : string, Password : string }
>>>>
>>>> ... snip ...
>>>>
>>>> fun checkPassword r =
>>>> let
>>>>    val cryptPass = {Email=r.Email, Password=Sha.hash r.Password}
>>>> in
>>>>    re' <- oneOrNoRows1(SELECT user.Id
>>>>                         FROM user
>>>>                        WHERE user.Email = {[cryptPass.Email]}
>>>>                          AND user.Password = {[cryptPass.Password]});
>>>>    case re' of
>>>>       None => return False
>>>>     | Some re => setCookie userSession { Value = cryptPass, 
>>>> Expires=None,Secure=False };
>>>>       return True
>>>> end
>>>
>>>
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>>
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