Yep this works: λ> import Data.Bits λ> let integerWithBytes = foldr (\byte acc -> (acc `shiftL` 8) + fromIntegral byte) 0 λ> integerWithBytes [0xFF

Yep this works: λ> import Data.Bits λ> let integerWithBytes = foldr (\byte acc -> (acc `shiftL` 8) + fromIntegral byte) 0 λ> integerWithBytes [0xFF, 0xFF, 0xFF, 0xFF] 4294967295