@persistent@ is a library for type-safe data serialization. It
has many kinds of backends, such as SQL backends
@persistent-sqlite@) and NoSQL backends (@persistent-mongoDB@).
While @persistent@ is a nice library for storing and retrieving
records, currently it has a poor interface for SQL backends
compared to SQL itself. For example, it's extremely hard to do
a type-safe @JOIN@ on a many-to-one relation, and simply
impossible to do any other kinds of @JOIN@s (including for the
very common many-to-many relations). Users have the option of
writing raw SQL, but that's error prone and not type-checked.
@esqueleto@ is a bare bones, type-safe EDSL for SQL queries
that works with unmodified @persistent@ SQL backends. Its
language closely resembles SQL, so (a) you don't have to learn
new concepts, just new syntax, and (b) it's fairly easy to
predict the generated SQL and optimize it for your backend.
Most kinds of errors committed when writing SQL are caught as
compile-time errors---although it is possible to write
type-checked @esqueleto@ queries that fail at runtime.
Currently only @SELECT@s are supported. Not all SQL features
are available, but most of them can be easily added (especially
functions), so please open an issue or send a pull request if
you need anything that is not covered by @esqueleto@ on
The name of this library means \"skeleton\" in Portuguese and
contains all three SQL letters in the correct order =). It was
inspired by Scala's Squeryl but created from scratch.