$ cabal install bloomfilter Resolving dependencies... Configuring bloomfilter-2.0.0.0... Building bloomfilter-2.0.0.0... Failed to install bloomfilter-2.0.0.0 Build log ( /Users/pengy/.cabal/logs/bloomfilter-2.0.0.0.log ): Configuring bloomfilter-2.0.0.0... Building bloomfilter-2.0.0.0... Preprocessing library bloomfilter-2.0.0.0... [1 of 7] Compiling Data.BloomFilter.Array ( Data/BloomFilter/Array.hs, dist/build/Data/BloomFilter/Array.o ) [2 of 7] Compiling Data.BloomFilter.Mutable.Internal ( Data/BloomFilter/Mutable/Internal.hs, dist/build/Data/BloomFilter/Mutable/Internal.o ) [3 of 7] Compiling Data.BloomFilter.Util ( Data/BloomFilter/Util.hs, dist/build/Data/BloomFilter/Util.o ) [4 of 7] Compiling Data.BloomFilter.Mutable ( Data/BloomFilter/Mutable.hs, dist/build/Data/BloomFilter/Mutable.o ) Data/BloomFilter/Mutable.hs:136:9: Non type-variable argument in the constraint: Data.Array.Base.MArray (Data.Array.Base.STUArray s) Hash m (Use FlexibleContexts to permit this) When checking that ‘loop’ has the inferred type loop :: forall (m :: * -> *). Data.Array.Base.MArray (Data.Array.Base.STUArray s) Hash m => [Int :* Int] -> m Bool In an equation for ‘elem’: elem elt mb = loop (hashesM mb elt) where mu = bitArray mb loop ((word :* bit) : wbs) = do { i <- unsafeRead mu word; .... } loop _ = return True cabal: Error: some packages failed to install: bloomfilter-2.0.0.0 failed during the building phase. The exception was: ExitFailure 1 -- Regards, Peng