What would these types be used for? If your students are complaining about having to perform logarithms to store integers, inform them of the "Integer" type. The existing sized types -- Word/Int [8, 16, 32, 64] -- are useful primarily because they match up with "standard" integral data types in other languages. They're great for FFI, (un)marshaling via ByteString, and occasional low-level code. In contrast, there is (to my knowledge) no machine with 42-bit integers, so there's no point to defining such intermediate types. In your FileSize example, it would be much easier to simply use: newtype FileSize = FileSize Integer since then your code will cope nicely when everybody upgrades to PB disks in a few years. If you need particular bounds, create your own instance of Bounded.