> The academic style probably blurs the fact that this has very deep practical applications Whilst this is certainly true, and worth pointing out, it's also ra

> The academic style probably blurs the fact that this has very deep practical applications Whilst this is certainly true, and worth pointing out, it's also rather a shame. The paper's abstract says exactly this, in quite a clear way, but I think many people wouldn't even make it as far as reading the abstract :( > List comprehensions are a widely used programming construct, in languages such as Haskell and Python and in technologies such as Microsoft's Language Integrated Query. They generalize from lists to arbitrary monads, yielding a lightweight idiom of imperative programming in a pure functional language. When the monad has the additional structure of a so-called ringad, corresponding to 'empty' and 'union' operations, then it can be seen as some kind of collection type, and the comprehension notation can also be extended to incorporate aggregations. Ringad comprehensions represent a convenient notation for expressing database queries. The ringad structure alone does not provide a good explanation or and efficient implementation of relational joins; but by allowing heterogeneous comprehensions, involving both bag and indexed table ringads, we show how to accommodate these too.