Write these in SML

1. Write these functions in ML(SML) :

• Write a function dup to double each element of an integer list. One function only. dup([2,3,5]) [2,2,3,3,5,5]
• Write a function dups to double each char of a string. Recursion must on list not string. dups("aabc") "aaaabbcc"
• Write a function mid to keep elements of an integer list between 5 and 10. One function only. mid [12,3,6,4,5,1] [6,5]