SQL
Nesting
All scalar functions can be arbitrarily nested.  
_Nested lambda functions to get all squares of even list elements:_  
```sql
SELECT list_transform(
list_filter([0, 1, 2, 3, 4, 5], x -> x % 2 = 0),
y -> y * y
);
```  
```text
[0, 4, 16]
```  
_Nested lambda function to add each element of the first list to the sum of the second list:_  
```sql
SELECT list_transform(
[1, 2, 3],
x -> list_reduce([4, 5, 6], (a, b) -> a + b) + x
);
```  
```text
[16, 17, 18]
```