E0037: runtime_signal_args

E0037 runtime_signal_args — the runtime section sends a signal with the wrong arguments.

A compile-time error of soma check, the checker of the Soma programming language (soma explain E0037).

The rule

A signal line in the runtime { } section must pass as many arguments as the interior handler of that name takes, and a literal argument must match the declared parameter type. Here a String literal is passed where the handler declares an Int, which would fail when soma run sends the signal. Pass a value of the declared type, for example an Int amount in cents instead of the text "49.99".

A program that triggers it

cell Shop {
    interior {
        cell Orders {
            face {
                signal order_placed(order_id: String, cents: Int)
            }
            on order_placed(order_id: String, cents: Int) {
                print("order {order_id}: {cents} cents")
            }
        }
    }
    runtime {
        signal order_placed("ord-1", "49.99")
    }
}

What soma check prints:

$ soma check wrong.cell
error: `signal order_placed(…)`: parameter 'cents' of Orders.order_placed is Int, and the runtime section passes a String literal
  --> wrong.cell:13:38
   |
13 |         signal order_placed("ord-1", "49.99")
   |                                      ^
  = code: E0037
✗ 1 error(s), 0 warning(s).

The fix field of soma check --json: `signal order_placed(…)`: parameter 'cents' of Orders.order_placed is Int, and the runtime section passes a String literal

The fix

On line 13, signal order_placed("ord-1", "49.99") becomes signal order_placed("ord-1", 4999).

--- wrong.cell
+++ right.cell
@@ -11,5 +11,5 @@
     }
     runtime {
-        signal order_placed("ord-1", "49.99")
+        signal order_placed("ord-1", 4999)
     }
 }

With the fix, soma check accepts the program:

$ soma check right.cell
✓ All checks passed.