[laylomo2]

Some clarifications:

It has one standard library, and several alternative standard libraries of varying popularity. I would argue that Core is probably the most popular. For what it's worth, Haskell also has several replacement for its standard library, Prelude.

For the syntax extensions, the community has largely migrated to PPX. Alternatives are being phased out.

String is no longer mutable in recent versions of OCaml. The string type is now immutable, and a new type, bytes, has been introduced which is mutable.