Ocaml : This expression has type int but an expression was expected of type int ref [closed]

Question

Having this code:

type player = Orange | Red | Blue | White ;;

type piece = 
    Knight of player 
  | Town of player 
  | City of player 
  | Road of player 
  | Wool of player 
  | Brick of player 
  | Lumber of player 
  | Grain of player 
  | Ore of player ;;

let posessions =
  [| Ore Orange; Road Red; Ore Blue; Ore White; 
     Lumber White; Ore Red; Knight Red; Road Orange; 
     Lumber Red; Brick Red; City White; Lumber White;
     Wool Red; City White; Ore White; Brick White; 
     Road Blue; Lumber Blue; Grain Orange; Wool Red; 
     Road White; Knight White; Grain White; Wool Orange; 
     City Blue; Ore Orange; Knight Orange; Brick White; 
     Ore Red; Ore White; Road Orange; Knight Red; 
     Lumber Orange; Wool Orange; City Orange; Wool Blue; 
     Lumber White; City Red; Grain Red; Lumber Red; 
     Ore White; Grain White; Brick Orange; Brick White; 
     Road Blue; Grain Red; Ore White; City White; 
     Road White; Knight Orange; Brick Red; Ore White; 
     Lumber Orange; Ore Blue; Road Blue; Brick White; 
     Brick Orange; Ore Orange; Ore Blue; Ore Orange; 
     Ore Orange; Brick Orange; Brick White; Road Orange; 
     Lumber White; Knight Red; Brick White; Brick Orange; 
     Road Blue; Brick Orange; Lumber Blue; Road Blue; 
     Ore Red; Grain Blue; Wool Red; Town Red; Ore Orange; 
     Lumber White; Road Red; Road Blue; Town Blue; 
     Wool Red; Lumber Blue; Wool Blue; Town Red; 
     Grain Orange; Brick Blue; Knight Red; Wool White;
     Ore Orange; Ore Blue; Lumber White; Wool White; 
     Brick Orange; Ore Blue; Grain Red; Wool Blue; 
     Road Red; Ore Blue; Lumber Orange |];;

let if_orange array =
  let counter = ref 0 
  and roadcounter = ref 0 
  and knightcounter = ref 0 
  and n = Array.length array in
  for i = 0 to n - 1 do 
    let a = Array.get array i in
      (if a = (Town Orange) then counter := !counter + 1
       else if a = (City Orange) then counter := !counter + 2
       else if a = (Road Orange) then roadcounter := !roadcounter + 1
       else if a = (Knight Orange) then knightcounter := !knightcounter + 1
       else counter := !counter + 0)
  done ;
  (if roadcounter >= 5 then counter := !counter + 2
   else counter := !counter + 0)
  (if knightcounter >= !3 then counter := !counter + 2
   else counter := !counter + 0 );
  !counter;; 

In for loop, I just wanted to add up some values to counter if the statements are valid. After it, I wanted to save the values for the counter, roadcounter and knightcounter. Then, in least to last if statement, increase the value of counter if roadcounter >= 5 (and save counter) and similarly for the knightcounter. However, I'm getting an error after I compile.

Error: This expression has type int but an expression was expected of type int ref

Am I supposed to int ref number 5 for comparison? Or did I somehow misplace the () or ;;?

Answer 1

Your problem is in this line:

if roadcounter >= 5 then

Indeed, roadcounter is an int ref, but you're comparing it to an int. You need ! before roadcounter.

There is a similar error a few lines later.

Update

Thanks for adding the types. However, they are not well formed. The definition of type piece stops abruptly in the middle of the keyword of.