Wanted: best way to express default expectations

[Jesse Phillips]

On Saturday, 12 October 2019 at 16:24:01 UTC, Jesse Phillips 
wrote:
> On Thursday, 10 October 2019 at 11:50:59 UTC, Dukc wrote:
>> On Thursday, 10 October 2019 at 11:47:21 UTC, Dukc wrote:
>>> On Thursday, 10 October 2019 at 11:44:58 UTC, Nicholas Wilson 
>>> wrote:
>>>>
>>>> https://dlang.org/phobos/std_algorithm_iteration.html#.filter
>>>
>>> For loops, that's an excellent choice. But what about early 
>>> function returns?
>>
>> And also, sometimes it's not practical to filter the range up 
>> front. You may also want to shortcut out in middle of the 
>> `foreach` body, or `break` out of an outer loop, or `return` 
>> instead of just aborting the loop.

Sorry forgot the foreach break part.

import std.stdio;
void main()
{
import std.algorithm;
import std.range;

foreach(i; iota(10)
    .filter!(x => x%2)
     .until!(x => x>5)
     .map!"a * a"
    .filter!(x => x%4)) {
     i.writeln;
     break;
    }
}

Note this is all done lazily so there is no walking of the iota 
which happens.