Question

I’m ocaml absolute beginner and I’m writing some code for classes and I’ve got a problem with such a line:

datatype logicexpr = Var of string
                 | Neg of logicexpr
                 | And of logicexpr * logicexpr
                 | Or of logicexpr * logicexpr;
let rec distributeLeft(X, And(e,f)) = And(distributeLeft(X, e),distributeLeft(Y, f)) 
| Or(X, Y);;

Why I get a syntax error here?

Answer 1

The function distributeLeft defined by:

fun distributeLeft(X, And(e,f)) = And(distributeLeft(X,e),distributeLeft(X,f))
| distributeLeft(X, Y) = Or(X, Y);

Can be translated in OCaml to something like:

let rec distibuteLeft = function
  | (X, And(e,f)) -> And(distributeLeft(X,e),distributeLeft(X,f))
  | (X, Y)        -> Or(X, Y)

And so on …