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{-# LANGUAGE MagicHash, BangPatterns #-}
module Main where
import GHC.Exts
{-# NOINLINE f #-}
f :: (Int# -> Float# -> Double# -> Float# -> Double# -> String) -> String
f g = g 3# 4.0# 5.0## 6.0# 6.9## ++ " World!"
{-# NOINLINE p #-}
p :: Int# -> Float# -> Double# -> Float# -> Double# -> String
p i j k l m = "Hello"
{-# NOINLINE q #-}
q :: Int# -> Int# -> Float# -> Double# -> Float# -> Double# -> String
q _ i j k l m = "Hello " ++ show (F# l) ++ " " ++ show (D# m)
{-# NOINLINE r #-}
r :: Int# -> Float# -> Double# -> Float# -> Double# -> String
r i = let !(I# z) = length [I# 1# .. I# i] in \j k l m -> p z j k l m
-- ghc won't eta-expand around the length, because it has unknown cost
main = do
putStrLn (f p) -- fast call
putStrLn (f r) -- slow call: function but wrong arity
let g = last [q 1#]
putStrLn (f g) -- slow call: thunk
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