Commit aab6b9bd authored by Joachim Breitner's avatar Joachim Breitner
Browse files

Call Arity test case: Check what happens with unboxed lets

parent 306d255d
include $(TOP)/mk/
include $(TOP)/mk/
{-# LANGUAGE MagicHash #-}
If the (unboxed, hence strict) "let thunk =" would survive to the CallArity
stage, it might yield wrong results (eta-expanding thunk and hence "cond" would
be called multiple times).
It does not actually happen (CallArity sees a "case"), so this test just
safe-guards against future changes here.
import Debug.Trace
import GHC.Exts
import System.Environment
cond :: Int# -> Bool
cond x = trace ("cond called with " ++ show (I# x)) True
{-# NOINLINE cond #-}
bar (I# x) =
let go n = let x = thunk n
in case n of
100# -> I# x
_ -> go (n +# 1#)
in go x
where thunk = if cond x then \x -> (x +# 1#) else \x -> (x -# 1#)
main = do
args <- getArgs
bar (length args) `seq` return ()
test('StrictLet', [], compile_and_run, [''])
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