Bs-knex orderBy

[thangngoc89]

Right now, the current signature of orderBy is like this:

orderBy: 'a => queryBuilder

It's translated to knex like this:

knex
.orderBy("columnName")

But what about this usage:

knex
.orderBy("columnName", "DESC")

A common pattern for binding I saw it add a new function like:

orderByWithDirection: (string, string) => queryBuilder

And since there is only too possible direction (ASC and DESC), we can use bucklescript's unwrap feature to make it typesafe with polymorphic variants