0.7.0.1

Version 0.7

Thanks to Samuel Schlesinger, Adam Wespiser, Cullin Poreski,
Matthew Doty and Mark Wotton for tons of contributions.
Version 0.7 of Squeal makes many changes.

Inter-schema Foreign Key Bug
Unfortunately, there was a bug in inter-schema foreign keys in previous
versions of Squeal. Essentially, it was erroneously assumed that
foreign keys always point to tables in the public schema. To remedy this
the ForeignKey type has changed kind from

>>> :kind 'ForeignKey
'ForeignKey :: [Symbol]
               -> Symbol -> [Symbol] -> TableConstraint

to

>>> :kind 'ForeignKey
'ForeignKey :: [Symbol]
               -> Symbol -> Symbol -> [Symbol] -> TableConstraint

To upgrade your database schemas type, you will have to change, e.g.

'ForeignKey '["foo_id1", "foo_id2"] "foo" '["id1", "id2"]

to

'ForeignKey '["foo_id1", "foo_id2"] "public" "foo" '["id1", "id2"]

Locking Clauses

You can now add row level locking clauses to your select queries

Polymorphic Lateral Contexts

Previously, lateral contexts which are used for lateral joins
and subquery expressions had to have monomorphic lateral contexts,
which greatly reduced composability of queries involving lateral
joins. Squeal 0.7 fixes this limitation, making it possible to
have polymorphic lateral context! When looking up a column heretofore,
the relevant typeclasses would search through Join lat from.
This is the "correct" ordering as far as the structure from
left to right in the query, making lat consistently ordered as
one goes through nested lateral joins or nested subquery expressions.
However, it doesn't really matter how the lookup orders the columns.
And if the lookup searches through Join from lat instead then thanks
to good old Haskell lazy list appending, if a query only references
columns in from then it will work no matter the lat.
With a small proviso; if you leave lat polymorphic,
then you must qualify all columns since there could be more than
one table even if from has only one table in it.

Decoders

The DecodeRow Monad now has a MonadFail instance.

New row decoder combinators have been added. The functions
appendRows and consRow let you build row decoders up
from pieces.

Previously, Squeal made it easy to decode enum types to Haskell
enum types (sum types with nullary constructors) so long as
the Haskell type exactly matches the enum type. However, because
of limitations in Haskell - constructors must be capitalized,
name conflicts are often disambiguated with extra letters, etc -
it's often the case that their constructors won't exactly match the
Postgres enum type's labels. The new function enumValue allows
to define typesafe custom enum decoders, similar to how rowValue
allows to define typesafe custom composite decoders.

>>> :{
data Dir = North | East | South | West
instance IsPG Dir where
  type PG Dir = 'PGenum '["north", "south", "east", "west"]
instance FromPG Dir where
  fromPG = enumValue $
    label @"north" North :*
    label @"south" South :*
    label @"east" East :*
    label @"west" West
:}

Definitions

New DDL statements have been added allowing to rename and
reset the schema of different schemum objects. Also, new DDL statements
have been added for adding comments to schemum objects.

Procedures

Squeal now supports procedure definitions and calls.

cmdTuples and cmdStatus

The cmdTuples and cmdStatus functions from LibPQ are now
included.

PQ Monad Instances

the PQ Monad has been given instances for MonadCatch,
MonadThrow, MonadMask, MonadBase, MonadBaseControl, and
MonadTransControl.

Referential Actions

A new type ReferentialAction has been factored out of
OnDeleteClauses and OnUpdateClauses. And Missing actions,
SetNotNull and SetDefault are now included.

To upgrade, change from e.g. OnDeleteCascade to OnDelete Cascade.

Array functions

Squeal now offers typesafe indexing for fixed length arrays and matrices,
with new functions index1 and index2. And new functions arrAny
and arrAll have been added to enable comparisons to any or all elements
of a variable length array.

Manipulations

Tables being manipulated are now re-aliasable, and updates can reference
"from" clauses, actually called UsingClauses in Squeal, similar to deletes.

Other changes
New tests and bugfixes have been added. More support for encoding and decoding
of different types has been added. Time values now use iso8601 formatting
for inlining. Also, the GitHub repo has moved from using Circle CI to using
GitHub Actions for continuous integration testing.