Below is the function
repeat written using a functional paradigm, such that when called as
repeat(square, 2)(5) it will apply the
2 times on the number
5, something like
def repeat(f, n): def identity(x): return x def apply_n_times(n): def recursive_apply(x): return apply_n_times(n - 1)(f(x)) if n < 0: raise ValueError("Cannot apply a function %d times" % (n)) elif n == 0: return identity else: return recursive_apply return apply_n_times(n) def square(x): return mul(x, x)
With regards to abstraction, I see that
repeat(square, 2) returns an implementation detail in the form of
apply_n_times(n - 1)(f(x)) multiple times before providing the actual result.
With regards to encapsulation, for the expression
f = repeat(square, 2) one could mutate the members of function object, for example:
Does the concept of
higher order function allow supporting abstraction and encapsulation? Because they return the implementation details and provide access for mutation.
Such existing implementations in large software are very tedious to use, as the user has to have an idea of the implementation before using it.