Home / Docs / Error Codes / GALA-E0075

GALA-E0075 — No default value

When it fires. GALA code needs a value of a type and none is written, and the type has no default value. That happens for:

• an uninitialized var x T;
• a field a construction leaves out, in a brace literal (Job{Name: "build"}) or a call;

when the type is a sealed type without a default case (Try, Either, most user sealed types), or a struct holding one. GALA never creates such a value implicitly: Go’s zero value of a sealed type without a default case is none of its cases.

Minimal repro.

package main

struct Job(Name string, Result Try[int])

func main() {
    val job = Job{Name: "build"}
    Println(job.Name)
}

Error output.

error[GALA-E0075]: field "Result" of "Job" is left out, and Try has no default value: it is a sealed type without a default case
  --> main.gala:6:15
  |
6 |     val job = Job{Name: "build"}
  |               ^^^ give Result a value
  |
  = hint: give Result a value

Fix. Give the value one of the type’s cases, or give the type a default case:

package main

struct Job(Name string, Result Try[int])

func main() {
    val job = Job{Name: "build", Result: Success(0)}
    Println(job.Name)
}

Rationale. A type’s default value is what GALA uses where its code needs a value and none is written: a sealed type’s default case built with its fields’ declared defaults, a struct with each field at its declared default or its type’s default value, and Go’s zero value for every other type. A type with no default value is one whose Go zero value means nothing, so GALA asks for a value instead. See Default Values.