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GALA-E0007 — Slice literal not supported

What it means. The source uses a Go-style slice literal ([]T{…}) as an expression. Slices are not a first-class GALA construct — they exist only behind the Go-interop boundary.

Code that triggers it

package main

func main() {
    val xs = []int{1, 2, 3}
    Println(xs)
}

Compiler message

error[GALA-E0007]: slice literals are not a first-class GALA construct
  --> e0007.gala:4:14
  |
4 |     val xs = []int{1, 2, 3}
  |              ^ use collection_immutable.Array or collection_mutable.Array f…
  |
  = hint: use collection_immutable.Array or collection_mutable.Array for type-safe collections, or go_interop.SliceOf()/SliceEmpty() for Go interop

How to fix it

Pick the replacement that matches your intent:

import . "martianoff/gala/collection_immutable"
import "martianoff/gala/go_interop"

val a = ArrayOf(1, 2, 3)              // immutable, type-safe GALA collection
val s = go_interop.SliceOf(1, 2, 3)   // raw Go []int, for passing to a Go API

Reach for go_interop.SliceOf only when a Go function actually demands a slice. Everything else — mapping, filtering, folding, sharing across goroutines — is better served by Array or List.

Why the rule exists

GALA’s type system reasons about immutable collections and explicit Go-interop shapes. A bare []int{…} sits outside that model and escapes silently into Go, discarding the compile-time guarantees that make GALA collections predictable (defensive copies, structural sharing, and shareability across goroutines). The error names the two canonical replacements so the choice stays explicit.