Ocaml Note On Syntax

Try not to omit parentheses and commas, especially for the function parameters and in the function calls...

This worked...

 let rec assoc (value, key, list)= match list with
 |[] -> value
 | (key', value')::tail -> if key = key' then value' else assoc(value, key, tail);;

But this didn't...

let rec assoc value key list = match list with

 |[] -> value

 | (key', value')::tail -> if key = key' then value' else assoc value key tail;;

Edit: I've found that this was the case for every recursive function with more than 1 parameter. Still unsure as to why...