[sparkie]

We probably wanna add to it to make it useful

    {-# LANGUAGE GeneralizedNewtypeDeriving #-}
   
    newtype Kilogram = Kilogram Double deriving (Show, Eq, Ord, Num, Real, Fractional, Floating, ...)

And remind ourselves that Haskell is really quite expressive.

[dllthomas]

Though unfortunately can't handle (mass * accel :: Newton) without swapping out the Prelude.