Error message?
│
├─ "undefined variable: X"
│   └─ Is X a builtin?
│       ├─ Yes → Import it: ailang builtins list | grep X
│       └─ No → Check spelling, define it
│
├─ "expected }, got ..."
│   └─ Missing semicolon between statements
│       Fix: let x = 1; let y = 2; x + y
│
├─ "No instance for Num[string]"
│   └─ Passing number to string function
│       Fix: print(show(42)) not print(42)
│
├─ "unexpected token: for/while/in"
│   └─ AILANG has no loops!
│       Fix: Use recursion with match
│
└─ Parse error with braces
    └─ Unmatched { } or missing expression
        Fix: Check all blocks are closed

-- WRONG
export func main() -> () ! {IO} {
  let x = 10
  let y = 20
  print(show(x + y))
}

-- CORRECT (semicolons between statements)
export func main() -> () ! {IO} {
  let x = 10;
  let y = 20;
  print(show(x + y))
}

-- WRONG: print expects string
print(42)

-- CORRECT: convert with show()
print(show(42))

-- WRONG: no for loops
for i in range(5) { print(show(i)) }

-- CORRECT: recursive function
export func printRange(n: int) -> () ! {IO} {
  if n <= 0 then () else {
    print(show(n));
    printRange(n - 1)
  }
}

-- WRONG: map not in scope
let doubled = map(\x. x * 2, nums)

-- CORRECT: import from std/list
import std/list (map)
let doubled = map(\x. x * 2, nums)

-- OR: write it yourself (recursion)
export func myMap[a,b](f: func(a) -> b, xs: [a]) -> [b] {
  match xs {
    [] => [],
    hd :: tl => f(hd) :: myMap(f, tl)
  }
}