[Ur] Calling an Ur/Web function from Javascript

[Adam Chlipala]

On 04/07/2013 08:50 PM, Istvan Chung wrote:
> On 04/07/2013 08:15 PM, Adam Chlipala wrote:
>    
>> On 04/07/2013 06:57 PM, Istvan Chung wrote:
>>      
>>> I'm trying to use the FFI to call an Ur/Web function from
>>> javascript, but there's very little in the manual about this; how
>>> can I do this? At present, anything I've tried has failed at
>>> compile time with the error: "Unsupported FFI function
>>> Module.functionName in JavaScript"
>>>        
>> The error message above is a little surprising to me, though.  How
>> does [Module.functionName] come into this?  Also, since that's an
>> urweb error message, what does it have to do with JavaScript code?
>>      
> By this I meant that Ur/Web had the (actual) name of the Ur/Web
> function there which I had tried to pass as a first-class value into
> javascript; I just wrote "Module.functionName" instead of the actual
> name of the module and function.
>    

This ([Module.functionName]) must have been an FFI function, in which 
case it makes sense that you'd need to use the 'jsFunc' .urp directive 
to declare which JavaScript function provides an implementation.