Question

IN SML

1. Write a function dupList of type 'a list -> 'a list whose output list is the same as the input list but with each element of the input list repeated twice in a row. For example, if the input is [1, 2, 3], the output list should produce [1, 1, 2, 2, 3, 3]. If the input list [], the output list should be [].

   • Do not use explicit recursion but use one of the fold functions. Do not write any additional functions, dupList should be the only function.

Answer 1

duplist is enough to get that output and You can achieve this in many ways I have used List Concatenation property and Sorted it to make output look alike your requirement.

Here is my function :

def dupList(initial):
    final = []
    final = sorted(initial+initial)
    return final
input_list = [1,2,3,4,5]
print(dupList(input_list))

Further if any query comment it

I will help you .

Have a nice day.