Polymorphic hash operates without type information, so it's not able to tell that it's hashing your record type vs. some other type with the same structure. So I would guess that what you want is not possible.

The Core team is working on a ppx extension analogous to ppx_sexp_conv and ppx_compare which generates hash functions automatically, and would make this kind of thing possible, but it's not done yet.

On 13 May 2016 at 15:52, Soegtrop, Michael <michael.soegtrop@intel.com> wrote:

Dear Ocaml Users,

I wonder if there is a way to specify a default hash function for a type, which is then used by the automated hash functions e.g. created for records containing this type. I have e.g. a record with about 10 fields and I am happy with the default hash functions for most fields and for the record, but for just one field I would like to use a custom hash function, but I don’t want to write a hash function for the record.

I am currently using the standard library, but if there is a solution with Batteries or Core, I would also be interested.

Best regards,

Michael

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