##
Understanding the `($)`

Operator in Haskell

The `($)`

operator is a type of function composition in Haskell, also known as the *apply* operator. It is defined as follows:

```
($) :: (a -> b) -> a -> b
f $ a = f a
```

This is nearly identical to the official definition, except that the official definition uses a sophisticated type `TYPE`

:

```
($) :: forall r a (b :: TYPE r). (a -> b) -> a -> b
f $ x = f x
```

The `TYPE`

type is a type-level computation, which allows programs to be written at the type-level. It is necessary in the `($)`

operator definition because it allows functions to be applied at the type-level, allowing for more efficient computation.