How can I filter out non-prime numbers in a list using Standard ML?

[azrarillian]

Hi, I'm using SML and I'm trying to make a program/function that finds all the prime numbers in an Int list of numbers.

what I'm trying to do is make a function that removes any (and all) elements x of the int list where x mod p = 0, and where p is the first prime number (2).

then i want to make a recursion so that it does the same for the next element after p, which should be a prime number.

the only problem i have is that i don't know how to filter or delete the elements x in the list. I've tried to use the function 'filter' but I can't figure out how to take modulo of the tail of the list (or rather of the elements in the tail) and the prime number.

please help...

also, I know that there are other ways to find primenumbers, and though this is the way i want to use (for now) any and all help, otherwise, is welcome.

 

[Future Bruno]

Here is one possible solution:fun primeList [] = [] | primeList (x::xs) = let val p = 2 in if x mod p = 0 then primeList xs else x :: primeList xs end;This function takes in a list of integers and recursively checks if the head of the list is divisible by the first prime number (p = 2). If it is, then it is removed and the function calls itself on the rest of the list. If it isn't, then it is added to the result list and the function calls itself on the rest of the list. This process continues until the list is empty, at which point the result list is returned.