On Thursday, 1 January 2026 at 17:01:25 UTC, zhade wrote:
Example:
```d
import std.algorithm : filter, map;
import std.typecons : tuple;
auto example_func(bool fail)
{
if (fail)
{
// [...]
}
auto list = someExpensiveOperation();
return list
.filter!(a => a != "expensive")
.map!(a => tuple!("value", "numLetters")(a, a.length));
}
string[] someExpensiveOperation()
{
return ["some", "expensive", "operation"];
}
```
You could try something like this:
```d
auto example_func(bool fail)
{
string[] list;
if (fail)
list = [];
else
list = someExpensiveOperation();
return list
.filter!(...)
.map!(...);
}
```
Because `map` and `filter` are lazy, calling them on an empty
`list` won't do anything, but they will still return the correct
type.
