Changes since Idris 2 v0.3.0 ============================ Library changes: * Introduced `test` package. - Moved `tests/Lib.idr` into new `test` package as `Test/Golden.idr`. - Removed `contrib/Test/Golden.idr` which duplicated the test framework now in the `test` package. REPL/IDE mode changes: * Added `:search` command, which searches for functions by type * `:load`/`:l` and `:cd` commands now only accept paths surrounded by double quotes Syntax changes: * The syntax for parameter blocks has been updated. It now allows to declare implicit parameters and give multiplicities for parameters. The old syntax is still available for compatibility purposes but will be removed in the future. Compiler changes: * Added more optimisations and transformations, particularly on case blocks, list-shaped types, and enumerations, so generated code will often be slightly faster. * Racket codegen now always uses `blodwen-sleep` instead of `idris2_sleep` in order to not block the Racket runtime when `sleep` is called. * Added `--profile` flag, which generates profile data if supported by a back end. Currently supported by the Chez and Racket back ends. * Javascript codegens now use `Number` to represent up to 32 bit precision signed and unsigned integers. `Int32` still goes via `BigInt` for multiplication to avoid precision issues when getting results larger than `Number.MAX_SAFE_INTEGER`. `Bits32` goes via `BigInt` for multiplication for the same reason as well as for all bitops, since `Number` uses signed 32 bit integers for those. * New code generator: `chez-sep`. This code generator produces many Chez Scheme files and compiles them separately instead of producing one huge Scheme program. This significantly reduces the amount of memory needed to build large programs. Since this backend will skip calling the Chez compiler on modules that haven't changed, it also leads to shorter compilation times in large codebases where only some files have changed -- for example when developing Idris2 code generators. The codegen has a large parallelisation potential but at the moment, it is significantly slower for a full rebuild of a large code base (the code generation stage takes about 3x longer). * New `%builtin` pragma for compiling user defined natural numbers to primitive `Integer`s (see the [docs](https://idris2.readthedocs.io/en/latest/reference/builtins.html)) API changes: * The API now exposes `Compiler.Separate.getCompilationUnits`, which can be used for separate code generation by any backend. Library changes: * Redid condition variables in the Racket codegen based on page 5 of the Microsoft [Implementing CVs paper](https://www.microsoft.com/en-us/research/wp-content/uploads/2004/12/ImplementingCVs.pdf). Previously, they were based on an implementation using semaphores and asynchronous channels, which worked apart from `broadcast`. The rework fixes `broadcast` at the cost of losing `wait-timeout` due to increased complexity of their internals and interactions between their associated functions. Other changes: * The `version` field in `.ipkg` files is now used. Packages are installed into a directory which includes its version number, and dependencies can have version number ranges using `<=`, `<`, `>=`, `>`, `==` to express version constraints. Version numbers must be in the form of integers, separated by dots (e.g. `1.0`, `0.3.0`, `3.1.4.1.5` etc) * Idris now looks in the current working directory, under a subdirectory `depends` for local installations of packages before looking globally. * Added an environment variable `IDRIS2_PACKAGE_PATH` for extending where to look for packages. Changes since Idris 2 v0.2.1 ---------------------------- Library changes: * Overhaul of the concurrency primitives: - Renamed `System.Concurrency.Raw` to `System.Concurrency`. - Modified the implementation of `Prelude.IO.fork` in the Chez Scheme RTS, which now returns a semaphore instead of a thread object. This allows the main thread to wait for the child thread to finish (see next bullet). The Racket implementation already returned a thread descriptor, which could be used to wait for the thread to finish. - Added `Prelude.IO.threadWait` which waits for a thread, identified by a `ThreadID`, to finish. This operation is supported by both the Chez Scheme and the Racket RTS'es. - Added semaphores to `System.Concurrency`, supported by both the Chez Scheme and Racket RTS'es. - Added barriers to `System.Concurrency`, supported by both the Chez Scheme and Racket RTS'es. - Added synchronous channels to `System.Concurrency`, supported by both the Chez Scheme and Racket RTS'es. - Fixed the support for mutexes in the Racket RTS. Formerly, they were implemented with semaphores, and calling`mutexRelease` multiple times would increment the internal counter multiple times, allowing multiple concurrent `mutexAcquire` operations to succeed simultaneously. Currently, `mutexRelease` fails when called on a mutex which isn't owned. (However, `mutexRelease` does not check whether the mutex is in fact owned by the current thread, which may be a bug.) - Modified the support for condition variables in the Racket RTS. Formerly, they were implemented using synchronous channels, meaning that: + `conditionSignal` was a blocking operation; and + calling `conditionSignal` on a condition variable on which no thread was waiting would wake the next thread to call `conditionWait`, whereas condition variables are supposed to be stateless, and only wake threads already in the queue. The implementation was replaced with an implementation based on asynchronous channels and mutexes, based on the following paper: [Implementing Condition Variables with Semaphores](https://www.microsoft.com/en-us/research/wp-content/uploads/2004/12/ImplementingCVs.pdf) by Andrew Birrell - Removed `threadID` and `blodwen-thisthread`. Formerly, in the Chez Scheme backend, this function returned "the thread id of the current thread" as a value of type `ThreadID`. However, `fork` returned a "thread object" as a value of type `ThreadID`. These are *different kinds of values* in Chez Scheme. As there was nothing one could do with a value of type `ThreadID`, I chose to remove `threadID`, as it allowed me to implement `threadWait` more easily. - Renamed `blodwen-lock` and `blodwen-unlock` to `blodwen-mutex-acquire` and `blodwen-mutex-release` for consistency, as these functions are referred to with acquire and release both in Chez Scheme and in the Idris2 concurrency module. * Added `Data.HVect` in `contrib`, for heterogeneous vectors. * Various other library functions added throughout `base` and `contrib` Command-line options changes: * Added `--color` and `--no-color` options for colored terminal output. Color is enabled by default. * Added `--console-width ` option for printing margins. By default the `auto` option is selected, the result is that the compiler detects the current terminal width and sets it as the option value, otherwise a user value can be provided. An explicit `0` has the effect of simulating a terminal with unbounded width. Language and compiler changes: * Removed multiplicity subtyping, as this is unsound and unfortunately causes more problems than it solves. This means you sometimes now need to write linear versions of functions as special cases. (Though note that the 1 multiplicity is still considered experimental, so hopefully this will change for the better in the future!) * Added new syntax for named applications of explicit arguments: `f {x [= t], x [= t], ...}` `f {x [= t], x [= t], ..., _}` * Added syntax for binding all explicit arguments (in the left hand side); `f {}` * Added new syntax for record updates (without the need for the `record` keyword): `{x := t, x $= t, ...}` * Local implementations of interfaces (in `let` or `where` blocks) now work, along with `%hint` annotations on local definitions, meaning that local definitions can be searched in auto implicit search. + Note, though, that there are still some known limitations (with both local hints and local implementations) which will be resolved in the next version. * New experimental ``refc`` code generator, which generates C with reference counting. * Added primitives to the parsing library used in the compiler to get more precise boundaries to the AST nodes `FC`. REPL/IDE mode changes: * Added `:color (on|off)` option for colored terminal output. * Added `:consolewidth (auto|n)` option for printing margins. Mirrors the command line option. Changes since Idris 2 v0.2.0 ---------------------------- Language changes: * `Bits8`, `Bits16`, `Bits32` and `Bits64` primitive types added, with: + `Num`, `Eq`, `Ord` and `Show` implementations. + Casts from `Integer`, for literals + Casts to `Int` (except for `Bits64` which might not fit), `Integer` and `String` + Passed to C FFI as `unsigned` + Primitives added in `Data.Buffer` * Elaborator reflection and quoting terms + Requires extension `%language ElabReflection` + API defined in `Language.Reflection`, including functions for getting types of global names, constructors of data types, and adding new top level declarations + Implemented `%macro` function flag, to remove the syntactic noise of invoking elaborator scripts. This means the function must always be fully applied, and is run under `%runElab` * Add `import X as Y` + This imports the module `X`, adding aliases for the definitions in namespace `Y`, so they can be referred to as `Y`. * `do` notation can now be qualified with a namespace + `MyDo.do` opens a `do` block where the `>>=` operator used is `MyDo.(>>=)` Library changes: * `IO` operations in the `prelude` and `base` libraries now use the `HasIO` interface, rather than using `IO` directly. * Experimental `Data.Linear.Array` added to `contrib`, supporting mutable linear arrays with constant time read/write, convertible to immutable arrays with constant time read. + Anything in `Data.Linear` in `contrib`, just like the rest of `contrib`, should be considered experimental with the API able to change at any time! Further experiments in `Data.Linear` are welcome :). * Experimental `Control.Linear.LIO` added to `contrib`, supporting computations which track the multiplicities of their return values, which allows linear resources to be tracked. * Added `Control.Monad.ST`, for update in-place via `STRef` (which is like `IORef`, but can escape from `IO`). Also added `Data.Ref` which provides an interface to both `IORef` and `STRef`. * Added `Control.ANSI` in `contrib`, for usage of ANSI escape codes for text styling and cursor/screen control in terminals. Command-line options changes: * Removed `--ide-mode-socket-with` option. `--ide-mode-socket` now accepts an optional `host:port` argument. * Added options to override source directory, build directory and output directory: `--source-dir`, `--build-dir`, `--output-dir`. + These options are also available as fields in the package description: `sourcedir`, `builddir`, `outputdir`. Compiler changes: * It is now possible to create new backends with minimal overhead. `Idris.Driver` exposes the function `mainWithCodegens` that takes a list of codegens. The feature in documented [here](https://idris2.readthedocs.io/en/latest/backends/custom.html). * New code generators `node` and `javascript`. REPL/IDE mode changes: * Implemented `:module` command, to load a module during a REPL session. * Implemented `:doc`, which displays documentation for a name. * Implemented `:browse`, which lists the names exported by a namespace. * Added `:psnext`, which continues the previous proof search, looking for the next type correct expression + Correspondingly, added the IDE mode command `proof-search-next` (which takes no arguments) * Added `:gdnext`, which continues the previous program search, looking for the next type correct implementation + Correspondingly, added the IDE mode command `generate-def-next` (which takes no arguments) * Improved program search to allow deconstructing intermediate values, and in simple cases, the result of recursive calls. Changes since Idris 2 v0.1.0 ---------------------------- The implementation is now self-hosted. To initialise the build, either use the [bootstrapping version of Idris2](https://github.com/edwinb/Idris2-boot) or build from the generated Scheme, using `make bootstrap`. Language changes: * `total`, `covering` and `partial` flags on functions now have an effect. * `%default ` has been implemented. By default, functions must be at least `covering` + That is, `%default covering` is the default status. * Fields of records can be accessed (and updated) using the dot syntax, such as `r.field1.field2` or `record { field1.field2 = 42 }`. For details, see [the "records" entry in the user manual](https://idris2.readthedocs.io/en/latest/reference/records.html) * New function flag `%tcinline` which means that the function should be inlined for the purposes of totality checking (but otherwise not inlined). This can be used as a hint for totality checking, to make the checker look inside functions that it otherwise might not. * %transform directive, for declaring transformation rules on runtime expressions. Transformation rules are automatically added for top level implementations of interfaces. * A %spec flag on functions which allows arguments to be marked for partial evaluation, following the rules from "Scrapping Your Inefficient Engine" (ICFP 2010, Brady & Hammond) * To improve error messages, one can use `with NS.name ` or `with [NS.name1, NS.name2, ...] ` to disable disambiguation for the given names in ``. Example: `with MyNS.(>>=) do ...`. Library additions: * Additional file management operations in `base` * New module in `base` for time (`System.Clock`) * New modules in `contrib` for JSON (`Language.JSON.*`); random numbers (`System.Random`) Compiler updates: * Data types with a single constructor, with a single unerased arguments, are translated to just that argument, to save repeated packing and unpacking. (c.f. `newtype` in Haskell) + A data type can opt out of this behaviour by specifying `noNewtype` in its options list. `noNewtype` allows code generators to apply special handling to the generated constructor/deconstructor, for a newtype-like data type, that would otherwise be optimised away. * 0-multiplicity constructor arguments are now properly erased, not just given a placeholder null value. Other improvements: * Various performance improvements in the typechecker: + Noting which metavariables are blocking unification constraints, so that they only get retried if those metavariables make progress. + Evaluating `fromInteger` at compile time. * Extend Idris2's literate mode to support reading Markdown and OrgMode files. For more details see: ["literate" in the user manual](https://idris2.readthedocs.io/en/latest/reference/literate.html). Changes since Idris 1 --------------------- Everything :). For full details, see: [updates](https://idris2.readthedocs.io/en/latest/updates/updates.html)