On Wed, May 2, 2018 at 12:27 PM, Simon Peyton Jones <simonpj at microsoft.com> wrote: > Wow. Could you open a ticket? Done: https://ghc.haskell.org/trac/ghc/ticket/15114 > I just tried with 8.2.2 which is what I have on this laptop, but it printed "all is well". Does that mean it was fine in 8.2, went wrong in 8.4.1 and was fixed in 8.4.2? It seems likely!