Question

I am implementing this hoemwork functionality using Ocaml:

• Not allowed to use List module
• the function has type 'a list list -> 'a list
• the function return a list consisting of the lists in x concatenated together (just top level of lists is concatenated, unlike List.flatten)
• For example : [[1,2,3],[45]] => [1,2,3,4,5] and [[[1,2,3],[4,5]],[[6,7]]] => [[1,2,3],[4,5],[6,7]]

I am not sure where to start, can anyone give me some suggestion? Thank you

Answer 1

I don’t see the difference between List.flatten and your function.

To answer to your question: as usual with lists, try to think about the base cases:

• what do you do when you concatenate an empty list with something ?
• what do you do when you concatenate a non-empty list (with a head and a tail) with something ?

Wrap everything into a pattern match, cook it for few hours, and that’s done 🙂