Re: [Caml-list] Robust left to right flow for record disambiguation

[Alain Frisch <alain@frisch.fr>]

On 10/25/2013 01:27 PM, Didier Remy wrote:
> I don't think specifying the information flow between left and right
> (always-left-to-right, always-right-to-left, or depending-on-examples) is a
> good design. This leads to non predictable type inference and less robust
> programs  : refactoring a function by just changing the order of parameters
> (and consistently changing the order of arguments in all uses of the
> function) may break existing programs and also require new annotations.

This is already the case, except for people using -principal.  I know it 
is recommended to use this option (at least once in a while), but I 
doubt many users actually do it.  (And FWIW, -principal is so slow on 
our code base that we cannot actually use it in practice -- this is 
probably related to the way we use object types.)

As a user, I think I'm willing to pay the price of risking having to add 
a few annotations on the next refactoring if this makes a very common 
idiom more practical.


> Also, such a biased will encourage people to write parameters of functions
> in an order that works well for the uses they have in mind.  I think it odd
> that type inference would have such an influence in choosing the order of
> function parameters.

If the ordering used for the (specified) information flow were drawn 
from the actual call site, labeled arguments would be a good solution.


Alain