Обсуждение: How to define template types in PostgreSQL

Dear all

MobilityDB (https://github.com/MobilityDB/MobilityDB) defines at the C level four template types: Set, Span, SpanSet, and Temporal. The type Set is akin to PostgreSQL's ArrayType restricted to one dimension, but enforces the constraint that sets do not have duplicates, the types Span and SpanSet are akin to PostgreSQL's RangeType and MultirangeType but enforce the constraints that span types are of fixed length and that empty spans and infinite bounds are not allowed, and the typeTemporal is used to manipulate time-varying values.

These template types need to be instantiated at the SQL level with base types (int, bigint, float, timestamptz, text, ...) and because of this, MobilityDB needs to define numerous SQL functions that all call the same function in C. Taking as example the Set type, we need to define, e.g.,

CREATE FUNCTION intset_eq(intset, intset) RETURNS bool AS 'MODULE_PATHNAME', 'Set_eq' ...
CREATE FUNCTION bigintset_eq(bigintset, bigintset) RETURNS bool AS 'MODULE_PATHNAME', 'Set_eq' ...
CREATE FUNCTION floatset_eq(floatset, floatset) RETURNS bool AS 'MODULE_PATHNAME', 'Set_eq' ...
CREATE FUNCTION textset_eq(textset, textset) RETURNS bool AS 'MODULE_PATHNAME', 'Set_eq' ...
...

CREATE FUNCTION intset_ne(intset, intset) RETURNS bool AS 'MODULE_PATHNAME', 'Set_ne' ...
CREATE FUNCTION bigintset_ne(bigintset, bigintset) RETURNS bool AS 'MODULE_PATHNAME', 'Set_ne' ...
CREATE FUNCTION floatset_ne(floatset, floatset) RETURNS bool AS 'MODULE_PATHNAME', 'Set_ne' ...
CREATE FUNCTION textset_ne(textset, textset) RETURNS bool AS 'MODULE_PATHNAME', 'Set_ne' ...
...

In the case of arrays, ranges, and multiranges, PostgreSQL avoids this redundancy using pseudo-types such as anyarray, anyrange, anymultirange, ...

Is there a possibility that we can also define pseudo types such as anyset, anyspan, anyspanset, anytemporal, .... ? 

This will considerably reduce the number of SQL functions to define. Currently, given the high number of functions in MobilityDB, creating the extension takes a loooong time ....

Regards

Esteban