On 12/21/06, Jeff Polakow <jeff.polakow@db.com> wrote:
>
> Principal typeings, which ML does not have, are useful because they allow for compositional type inference (i.e. each piece of the program can be analyzed separately).
>
>

According to a 2005 paper by Camarao and Figueiredo (found at
http://www.dcc.ufmg.br/~camarao/ml-has-pt.pdf ), there is a variation
of the usual Damas-Milner type system for core-ML that types the same
terms and also has principal typings.

So the language ML does have principal typings, in the sense that it
has a useful type system with principal typings, but afaik no ML
implementation uses a such a type system.