Crash in defunctionalisation

[athas]

Pretty sure the actual issue is that lambda lifting produces some nonsense code by neglecting to transform expressions in types (but why do we even still have those at that point?)

def index_of_first p xs =
  loop i = 0 while i < length xs && !p xs[i] do i + 1

def span p xs = let i = index_of_first p xs in (take i xs, drop i xs)

entry part1 [l] (ls: [][l]i32) =
  let blank (l: [l]i32) = null l
  in span blank ls |> \(x, y) -> (id x, tail y)