Summary:
Remove the remaining uses of polymorphic equality `=`.
In case of basic types, this is replaced by String.equal or Int.equal.
In case of `= []`, this is replaced by `List.is_empty`.
In case of `= None`, this is replaced by `is_none`.
In case of a datatype definition such as `type a = A | B`,
a `compare_a` function is defined by adding `type a = A | B [@deriving compare]`
and a `equal_a` function is defined as `let equal_a = [%compare.equal : a]`.
In case of comparison with a polymorphic variant `= `Yes`, the equality
defined in `PVariant.(=)` is used. Typically, `open! Pvariant` is added
at the beginning of the file to cover all the uses.
Reviewed By: jberdine
Differential Revision: D4456129
fbshipit-source-id: f31c433
Andrzej Kotulski
Cristiano Calcagno
Dulma Churchill
Dino Distefano