Count all the elements larger than x in a list

Question

I'm doing some exercise in "List" and "Match-With" but I'm a little stuck.

The exercise tell me Program the upper l x function that counts all the elements larger than x in the list

Example :

upper [10;20;30;40;50] 35; 

the results is 2.

I did this :

let rec upper x l1 =
  match l1 with
  |[] -> 0
  |[a] -> if (a>x) then 1 else 0
  |(a::r) when a>x -> +1 
  |(a::r) when a<x -> upper x r

but nothings work.

Answer 1

Your solution looks pretty good, except this expression:

+1

doesn't make a lot of sense. It's just another way of writing the number 1. Clearly the answer isn't 1 in this case. For one thing, the answer depends on the count for the tail of the list r.

A problem for later is that a > x and a < x do not cover all the cases. In particular, they don't cover the case when a = x.