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GALA-E0047 — if takes no initializer statement

What it means. An if is written with Go’s initializer statement — a binding, then ;, then the condition. The construct is Go’s, not GALA’s.

Code that triggers it

package main

import "strconv"

func isParsable(text string) bool {
    if n, err := strconv.Atoi(text); err != nil {
        Println(n)
        return false
    }
    return true
}

func main() {
    Println(isParsable("42"))
}

Compiler message

error[GALA-E0047]: `if` takes no initializer statement
  --> main.gala:6:5
  |
6 |     if n, err := strconv.Atoi(text); err != nil {
  |     ^^ wrap the call in `Try(...)` and `match` on `Success(v)` / `F…
  |
  = hint: wrap the call in `Try(...)` and `match` on `Success(v)` / `Failure(e)` — a Go `(T, error)` return is auto-wrapped

How to fix it

The shape this slot is reached for is almost always a Go (T, error) call being nil-tested, and Try wraps exactly that shape:

func parseOr(text string, fallback int) int =
    Try(strconv.Atoi(text)) match {
        case Success(n) => n
        case Failure(_) => fallback
    }

GetOrElse says the same thing when the failure is simply a fallback:

func parseOr(text string, fallback int) int =
    Try(strconv.Atoi(text)).GetOrElse(fallback)

A differently-placed nil comparison — val err = f() on the line above, then if err != nil — is not the fix: it trades one Go idiom for another and leaves the naked error pair in place. See Error Handling.

Why the rule exists

Nothing ever lowered the initializer correctly. The binding was transformed after the condition that references it, so the generated Go compared the std.Immutable[T] wrapper rather than the value — an error naming a wrapper the author never wrote. A multi-value initializer lowered to a var (...) block, which Go does not accept there at all.

Only the initializer slot is rejected. A plain condition, else, else if chains, and the if-expression if (cond) a else b are untouched.