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(USING ML) (Using ML) Write a function dupList of type 'a list -> 'a list whose...

(USING ML)

(Using ML)

  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.

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Q:- 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:------
fun dupList l = foldr(fn (a, b) => a::a::b) [] l;

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