catala/tests/test_array/good/aggregation_3.catala_en

```catala
declaration scope S:
  output x content integer

scope S:
    definition x equals 0

# Map
    assertion (i + 2) for i among [1; 2; 3] = [3; 4; 5]

# Filter
    assertion (i among [1; 2; 3] such that i >= 2) = [2; 3]

# Sum
    assertion sum integer of [1; 2; 3] = 6
    assertion sum integer of (i + 2) for i among [1; 2; 3] = 12

# Count
    assertion number of [1; 2; 3] = 3
    assertion (number of i among [1; 2; 3] such that i >= 2) = 2

# Extremum
    assertion maximum of [1; 2; 3] or if collection empty then 10 = 3
    assertion maximum of (decimal of i) for i among [1; 2; 3] or if collection empty then 10. = 3.

# Arg extremum
    assertion (i among [1; 2; 3]
                 such that decimal of ((2 - i) * (2 - i)) is minimum
                 or if collection empty then 42)
              = 2
```

```catala-test-inline
$ catala scopelang -s S
let scope S (x: integer|internal|output) =
  let x : integer = ⟨true ⊢ 0⟩;
  assert reduce
           (λ (x1: integer) (x2: integer) →
              if
                let i : integer = x1 in
                  to_rat_int 2 -! i *! 2 -! i <.
                  let i : integer = x2 in
                  to_rat_int 2 -! i *! 2 -! i then x1 else x2) 42 [1; 2; 3] =
           2;
  assert reduce
           (λ (x1: decimal) (x2: decimal) → if x1 >. x2 then x1 else x2)
           10. map (λ (i: integer) → to_rat_int i) [1; 2; 3] = 3.;
  assert reduce
           (λ (x1: integer) (x2: integer) → if x1 >! x2 then x1 else x2)
           10 [1; 2; 3] = 3;
  assert length filter (λ (i: integer) → i >=! 2) [1; 2; 3] = 2;
  assert length [1; 2; 3] = 3;
  assert reduce (λ (x1: integer) (x2: integer) → x1 +! x2) 0
           map (λ (i: integer) → i +! 2) [1; 2; 3] = 12;
  assert reduce (λ (x1: integer) (x2: integer) → x1 +! x2) 0 [1; 2; 3] = 6;
  assert filter (λ (i: integer) → i >=! 2) [1; 2; 3] = [2; 3];
  assert map (λ (i: integer) → i +! 2) [1; 2; 3] = [3; 4; 5]
```

```catala-test-inline
$ catala interpret -s S
[RESULT] Computation successful! Results:
[RESULT] x = 0
```