If 2 is an overloaded literal, and + is an overloaded operator, we’ll need something more than equality constraints to handle that.

An attractive solution is type classes as in Haskell, in this case Num:

class Num a where
    fromInteger : Integer -> a
    (+) : a -> a -> a

Literals like 2 is then taken to mean fromInteger 2, which has the type Num a => a — here a can be any type that adheres to the Num a type class constraint, i.e. an instance is defined for it. We’d then introduce the following instances:

instance Num Int8 where ...
instance Num Uint where ...
instance Num Float where ...

I’ll cover type class constraints later in the series.