CODEWITHSUNDEEP
ml
auditornwann
auditornwann

Reputation: 3

Deleting middle element out of a given list in ML

I am brand new to learning standard ML. I want to make a function that takes a list/lists of 3 numbers and deletes the middle number and then reverse the order of the two numbers. So if I have a input of (3, 4, 5) then I want to return (5, 3).

This is what I have so far:

fun twiddle [] = [] | twiddle (x::xs) = x::twiddle xs;

I am not sure how to distinguish the middle item of the list and then delete it.

Upvotes: 0

Views: 63

Answers (1)

molbdnilo
molbdnilo

Reputation: 66459

If there are always three numbers, use a pattern matching three elements:

fun twiddle [a,b,c] = [c,a]

Upvotes: 1

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