[jhc] How newStablePtr return un-packable IO ()?

Hi, jhc hackers. Now, I am trying create forkOS with pthread. But StablePtr error stops it. Jhc's newStablePtr cannot pack IO () for running with unpack. $ cat Main.hs import Foreign.StablePtr main :: IO () main = do p <- newStablePtr $ print "hoge" d <- deRefStablePtr p d casper$ ajhc Main.hs ajhc Main.hs ajhc 0.8.0.5 (b6d58e95e63be9848f267e9242dedff5e5f7b25b) Finding Dependencies... Using Ho Cache: '/home/kiwamu/.ajhc/cache' Main [Main.hs] <~/.ajhc/cache/c41ljd5d48u6h86r9ap27k0vq2.ho> Fresh: <~/.ajhc/cache/c41ljd5d48u6h86r9ap27k0vq2.ho> Typechecking... Compiling... Collected Compilation... -- TypeAnalyzeMethods -- BoxifyProgram -- Boxy WorkWrap -- LambdaLift Converting to Grin... Updatable CAFS: 0 Constant CAFS: 0 Recursive CAFS: 0 ajhc: Grin.FromE.compile'.ce in function: theMain can't grok expression: x62470114 How newStablePtr return un-packable IO ()? Best regards, -- Kiwamu Okabe