Since version 0.2.9 that I’ve just released, esqueleto supports
EXISTS operators (and their negated counterparts). For example:
from $ \person -> do
where_ $ exists $
from $ \post -> do
where_ (post ^. BlogPostAuthorId ==. person ^. PersonId)
PS: I’ll try to post more in the future, so keep tuned =).
I’m very pleased to announce a preview release of esqueleto, a bare bones, type-safe EDSL for SQL queries.
Yesod is a terrific framework for web applications in Haskell. It has many, many built-in features. One of them is that there’s nice support for authentication and authorization. In this post I’m interested in talking about how you could write your authorization code such that it’s harder to make mistakes.