21 Tuple and relation types as first class citizens

A general purpose programming language should support parameterised tuple and relation types, and the operations of the relational algebra as first class citizens []

This would allow code like the following:

    auto R1 = relation<int x, int y>{
        {(x,1), (y,2)},
        {(x,1), (y,5)} };

    auto R2 = relation<int y, int z>{
        {(y,2), (z,10)},
        {(y,2), (z,20)},
        {(y,3), (z,4)} };

    auto R3 = PROJECT<x,z>((R1 JOIN R2) WHERE x>0);

and the compiler deduces the type of R3.

This approach eliminates the need for an O/R Mapping, and the limitations involved with using OO to manage collections of facts.