pub fn and(p1: fn(a) -> Bool, p2: fn(a) -> Bool) -> fn(a) -> Bool

let is_even = fn(x) { x % 2 == 0 }
let is_positive = fn(x) { x > 0 }
let is_even_and_positive = and(is_even, is_positive)
is_even_and_positive(4) // True
is_even_and_positive(3) // False
is_even_and_positive(-2) // False

pub fn not(p: fn(a) -> Bool) -> fn(a) -> Bool

let is_even = fn(x) { x % 2 == 0 }
let is_odd = not(is_even)
is_odd(3) // True
is_odd(4) // False

pub fn or(p1: fn(a) -> Bool, p2: fn(a) -> Bool) -> fn(a) -> Bool

let is_even = fn(x) { x % 2 == 0 }
let is_positive = fn(x) { x > 0 }
let is_even_or_positive = or(is_even, is_positive)
is_even_or_positive(3) // True (positive)
is_even_or_positive(4) // True (both)
is_even_or_positive(-1) // False (neither)