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{-# LANGUAGE MagicHash #-}
module Main ( main ) where
import Foreign
import Foreign.C
import GHC.Exts
data CList = CNil | CCons Int# CList
mk :: Int# -> CList
mk n = if isTrue# (n ==# 0#)
then CNil
else CCons 1# (mk (n -# 1#))
clen :: CList -> Int#
clen CNil = 0#
clen (CCons _ cl) = 1# +# (clen cl)
main = case (clen list4) of
len4 ->
case (len4 +# len4) of
8# -> finish 65# -- 'A'
_ -> finish 66# -- 'B'
where
list4 = mk 4#
finish :: Int# -> IO ()
finish n = c_putchar (castCharToCChar (C# (chr# n))) >> return ()
foreign import ccall unsafe "putchar"
c_putchar :: CChar -> IO CInt
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