Newtypes of unboxable types cannot be unboxed in arrays any more
Perhaps since 616e33c0, it is no longer possible to define unboxed arrays of newtypes, so that the following program fails to compile with "I instance cannot be unboxed":
import StdEnv
:: I =: I Int
Start :: {#I}
Start = {I 5}
Edited by Camil Staps