ERROR: Inserting EQUALOP

Question

Hi can someone help me figure why i get the

ERROR: Inserting EQUALOP

for the following code?

fun generator inchan outchan n = if n>0                         
           then 
               (let 
                   fun loop () =                          
                         val c = recv(outchan)
                         val _ = send (inchan, c)
                in  
                   (loop ();(generator inchan outchan (n-1)))
                end)
            else inchan;

Answer 1

You enter a let statement, and then define a function. However, inside that function, you seem to want to define more variables. To do this, you need another let statement. Without it, you will get a syntax error like this.

Try using this instead:

fun loop () = send (inchan, recv (outchan))

Or, if you want the separate lines for more clarity:

fun loop () =
    let
      val c = recv (outchan)
    in
      send (inchan, c)
    end

Or maybe

fun loop () = 
    let
      val c = recv (outchan)
      val _ = send (inchan, c)
    in
      ()
    end