package fp

// Fold applies a function to each element in the slice and accumulates the result.
// It takes a slice of type T, an initial value of type A, and a function that combines the accumulator value with each element of the slice.
// The function returns the final accumulated value.
func Fold[A any, T any](s []T, a A, f func(A, T) A) A {
	for i := range s {
		a = f(a, s[i])
	}
	return a
}

// Map applies the function f to each element of the slice s and returns a new slice
// containing the results.
//
// The returned slice will contain elements of type M, which is the result
// type of the function f.
//
// Example usage:
//
//	numbers := []int{1, 2, 3, 4, 5}
//	doubled := Map(numbers, func(n int) int {
//	  return n * 2
//	})
//	// doubled is now []int{2, 4, 6, 8, 10}
//
//	names := []string{"Alice", "Bob", "Charlie"}
//	lengths := Map(names, func(name string) int {
//	  return len(name)
//	})
//	// lengths is now []int{5, 3, 7}
//
// Note: The input slice s is not modified by this function.
func Map[T, M any](s []T, f func(T) M) []M {
	res := []M{}
	for i := range s {
		res = append(res, f(s[i]))
	}
	return res
}