# 2020-05-25 (v0.8) * refactor backend to maximize laziness: [An Architecture for Data Independence](docs/data_independence.markdown) # 2019-09-07 (v0.7) * fix case sensitivity issue with relation variables in tutd * fix multibyte escaping in data frames * fix broken instances of `Atomable [a]` * fix `TypeConstructor` validation of argument count * add help option to executables # 2019-01-08 (v0.6) * fix atom type parsing to support more complex data types * add [data frames](docs/dataframes.markdown) to support server-side sort ordering, limits, and offsets # 2018-10-03 (v0.5.1) * fix atom function type validation * add support for GHC 8.4 (now we support GHC 8.0, 8.2, and 8.4) # 2018-08-10 (v0.5) * fix critical type bug which allowed unresolved types to be used * add full support for GHC 8.2 with stack or cabal (delayed for a long time by dependency version boundaries) * drop support for GHC 7.10 * add support for `with (relexpr as name,...)` syntax for use as tutd macros * add `NonEmptyList` list data type # 2018-06-04 (v0.4) * add contributed feature to allow users to [create arbitrary relations](https://github.com/agentm/project-m36/blob/master/docs/tutd_tutorial.markdown#arbitrary-relation-variables) * fix type validation bug allowing concrete type with type variables in relations * improve usability of `Interval a` data type * allow `Integer` to be parsed as negative in `tutd` console * support precompiled (Haskell) [`AtomFunction`s](https://github.com/agentm/project-m36/blob/master/docs/atomfunctions.markdown#pre-compiled-atom-functions) and [`DatabaseContextFunction`s](https://github.com/agentm/project-m36/blob/master/docs/database_context_functions.markdown#loading-precompiled-modules) * make TutorialD scripts read from the filesystem unconditionally read as UTF-8 * improve support for display of multibyte characters in `tutd` console, especially Chinese * fix file descriptor leak in file sychronization * improve reliability by allowing fast-forward commits when using `autoMergeToHead` * add [`semijoin` and `anitjoin`](https://github.com/agentm/project-m36/blob/master/docs/tutd_tutorial.markdown#join) support to `tutd` * added various new static optimizations # 2017-11-14 * alter websocket server API to allow for multiple representations (JSON, text, or HTML) to be selected and returned simultaneously * add jupyter kernel for TutorialD interpreter * fix warnings suggested by new hlint 2.0.10 # 2017-10-08 (v0.3) * replaced overuse of `undefined` with `Proxy` in `Tupleable` and `Atomable` typeclasses * allow notifications to return query results from before *and* after the commit which triggered the notification * alert users in `tutd` console before a transaction graph expression is evaluated which would throw out their changes * drastically-improved CSV import/export now supports all possible types except `RelationAtom` * fix serious file handle leaks when using on-disk persistence * fix case where invalid number of arguments to `ConstructedAtom` did not result in an error * add support for `IntegerAtom` (previously, only `IntAtom` was supported) # 2017-09-16 (v0.2) * a new [simple client API](https://github.com/agentm/project-m36/blob/master/docs/simple_api.markdown) with a monadic transaction manager * complete hlint compliance * the generics-based [Tupleable typeclass]( https://github.com/agentm/project-m36/blob/master/docs/tupleable.markdown ) which makes it easy to marshal Haskell data types to-and-from the database * timestamps attached to transactions to allow specific point-in-time travel * autoMergeToHead, a variant of commit which attempts to merge and commit to the latest head transaction to reduce incidents of TransactionNotAHeadErrors * interval data types * transaction dirtiness detection which allows the client to determine if an update expression actually changed the database state # 2017-08-01 ## autoMergeToHead In preparation for the simpler monad client API, ProjectM36.Client now includes a server-side merge for new transactions called "[automerge](https://github.com/agentm/project-m36/issues/33)". This feature should reduce head contention in cases where new transactions can be simply merged to the head without additional processing. The trade-off is reduced ```TransactionIsNotAHeadError```s but an increased chance of merge errors. The feature operates similarly to a server-side git rebase. ## critical bug in merging Successfully merged transactions did not have their constraints validated. Fixed. # 2017-06-12 ## add file locking This [feature](#102) allows Project:M36 database directories to be shared amongst multiple Project:M36 processes. This is similar to how SQLite operates except that the remote server mode supports the feature as well. This could allow, for example, multi-master, file-based replication across Windows shares or NFS. [Documentation](/docs/replication.markdown) # 2016-11-30 ## add functional dependency macro Date demonstrates two ways to implement functional dependencies as constraints on page 21 in "Database Design and Relational Theory". A similar macros is now implemented in the tutd interpreter. ```funcdep sname_status (sname) -> (status) s``` [Documentation](/docs/tutd_tutorial.markdown#functional-dependencies) # 2016-09-07 ## add TransGraphRelationalExpr The TransGraphRelationalExpr allows queries against all past states of the database. The following example executes a query against two different committed transactions using syntax similar to that of git for graph traversal: ```:showtransgraphexpr s@master~ join sp@master``` [Documentation](/docs/transgraphrelationalexpr.markdown)