I felt like one or two decades ago, all the rage was about rewriting programs into just two primitives: map and reduce.

For example filter can be expressed as:

  is_even = lambda x: x % 2 == 0
  mapped = map(lambda x: [x] if is_even(x) else [], data)
  filtered = reduce(lambda x, y: x + y, mapped, [])

Performance aside it seems you could do most maybe a the ops with those three. I say three because your sneaky plus is a union operation. So map, reduce and union.

But you are also allowing arbitrary code expressions. So it is less lego-like.