String Interpolation

[Walter Bright]

On 10/21/2023 5:38 AM, Commander Zot wrote:
> can we please just have ```i"whatever ${var}"``` to return a fully interpolated 
> string, not a tuple, not a template or anything.
> because the common use case is ```auto s = i"whatever ${var}";```,
> so maybe just lower it into ```format("whatever %s", var)```.

Better tuple support is in the cards for D. They should be pretty straightforward.

For DIP1027,

```
int var = 67;
auto s = format(i"whatever $var");
```
would be equivalent to:
```
auto s = "whatever 67";
```

I.e. there are two steps involved:

1. convert the istring to a tuple
2. convert the tuple to a string

Having them be two steps enables the user to insert step 2:

1. convert the istring to a tuple
2. modify the tuple
3. convert the tuple to a string