Comprehending Ringads

Comprehending Ringads

2016 by Jeremy Gibbons

Ringad comprehensions represent a convenient notation for expressing database queries. The ringad structure alone does not provide a good explanation or an efficient implementation of relational joins; but by allowing heterogeneous comprehensions, involving both bag and indexed table ringads, we show how to accommodate these too.

Indexed/parametric/graded monads are the key (read the paper to understand the pun).