[Swift-devel] folding/sequential-while/whatever and accessing data in files

[Michael Wilde]

The retval file would have a fixed format: multiple lines of "name 
value".  And it would only be used to return scalars or lists of 
scalars: basically the same kinds of values that you can express as 
swift literals. In this case:
--
error 21
perror "Threshold exceeded"
--

The variable "next" is a file or dataset and needs to be passed using 
the current file mapping conventions.

With some thought, this could be generalized further to allow retval 
expansion *within* a dataset, so any dataset could have an arbitrary 
number of scalar values as fields along with file values.

- Mike

Ben Clifford wrote:
> 
> On Fri, 7 Sep 2007, Michael Wilde wrote:
> 
>> (int error, string perror, SomeFile next ) new_approximation (previous)
>> {
>>   app RETVAL { ... }
>> }
>>
>> The RETVAL keyword (caps mine) would signify that the app will produce a
>> RETVAL file and that the runtime system should use this file to set return
>> values as it indicates.
> 
> That's very similar to execute-side mapping (which has been discussed) + 
> application-side filecontent->value mapping.
> 
> In the syntax example above, there's no place to specify the format in 
> which the return value file is to be converted into the three swift values 
> (int error, string perror, SomeFile next ).
>