DIP 1009--Improve Contract Usability--Preliminary Review Round 1

[Timon Gehr via Digitalmars-d]

On 22.06.2017 22:43, jmh530 wrote:
> On Thursday, 22 June 2017 at 20:19:59 UTC, Timon Gehr wrote:
>> On 22.06.2017 22:02, jmh530 wrote:
>>>
>>> The whole double parentheses is a bit ugly to me. Is there any 
>>> problem with
>>> out(return > 0)
>>
>> out(a => {
>>     void foo()out(b => a == b){ return a; }
>>     return foo()>0;
>> }());
> 
> I'm confused. The compiler should know that these returns are inside 
> lambdas.

The point is that two results are in scope, so you cannot call both of 
them 'return'. It's a corner case, but you asked for any problems.

> Also, foo should not return void

Oops. That's a typo. Fixed version:

out(a => {
     int foo()out(b => a == b){ return a; }
     return foo()>0;
}())

> and I'm not sure what the 
> extra set of parentheses are for at the end.

That's calling the lambda.

Version that works today:

int bar()out(a){
     int foo()out(b){
         assert(a==b);
     }body{
         return a;
     }
     assert(foo()>0);
}body{
     return 2;
}