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{-# LANGUAGE UnboxedTuples, MagicHash, BangPatterns #-} module ShouldCompile where import Data.Ix import GHC.Exts f ixs@(_, ix_end) frozen# = let !n# = case ( if null (range ixs) then 0 else 1 ) of { I# x -> x } in (# frozen#, False #)