E0075: no_initial_state

E0075 no_initial_state — a state machine without initial:.

A compile-time error of soma check, the checker of the Soma programming language (soma explain E0075).

The rule

A state machine needs a start state. Check reports this code for a machine with no initial: line and no transitions; when initial: is missing but the first edge has an ordinary source state, the binary takes that state as the start instead of reporting this code. Add initial: <state> as the first line of the machine.

A program that triggers it

cell Shipment {
    memory {
        parcels: Map<String, String> [persistent]
    }
    state delivery {
    }
    on register(id: String, address: String) {
        parcels.set(id, address)
        return id
    }
}

What soma check prints:

$ soma check wrong.cell
error: state machine 'delivery' has no start state — add `initial: state` as its first line
  --> wrong.cell:5:5
  |
5 |     state delivery {
  |     ^
  = code: E0075
✗ 1 error(s), 0 warning(s).

The fix field of soma check --json: add `initial: state` as its first line

The fix

1 line is added after line 5.

--- wrong.cell
+++ right.cell
@@ -4,4 +4,5 @@
     }
     state delivery {
+        initial: registered
     }
     on register(id: String, address: String) {

With the fix, soma check accepts the program:

$ soma check right.cell
✓ All checks passed.