# Changelog ## [Next version] ### REPL changes * New experimental Scheme based evaluator (only available if compiled via Chez scheme or Racket). To access this at the REPL, set the evaluator mode to the scheme based evaluator with `:set eval scheme`. * New option `evaltiming` to time how long an evaluation takes at the REPL, set with `:set evaltiming`. * Renames `:lp/loadpackage` to `:package`. ### Language changes * There were two versions of record syntax used when updating records: ```idris record { field = value } r ``` and ```idris { field := value } r ``` The former is now deprecated in favour of the latter syntax. The compiler will issue a warning when using the `record` keyword. * Interpolated strings now make use of `concat` which is compiled into `fastConcat` The interpolated slices now make use of the `Interpolation` interface available in the prelude. It has only one method `interpolate` which is called for every expression that appears within an interpolation slice. ```idris "hello \{world}" ``` is desugared into ```idris concat [interpolate "hello ", interpolate world] ``` This allows you to write expressions within slices without having to call `show` but for this you need to implement the `Interpolation` interface for each type that you intend to use within an interpolation slice. The reason for not reusing `Show` is that `Interpolation` and `Show` have conflicting semantics, typically this is the case for `String` which adds double quotes around the string. ### Compiler changes * Removes deprecated support for `void` primitive. Now `void` is supported via `prim__void`. * Adds `%deprecate` pragma that can be used to warn when deprecated functions are used. * Package files now support a `langversion` field that can be used to specify what versions of Idris a package supports. As with dependency versions, `>`, `<`, `>=`, and `<=` can all be used. + For example, `langversion >= 0.5.1`. ### IDE protocol changes * The IDE protocol and its serialisation to S-Expressions are factored into a separate module hierarchy Protocol.{Hex, SExp, IDE}. * File context ranges sent in the IDE protocol follow the same convention as Bounds values in the parser: + all offsets (line and column) are 0-based. + Lines: start and end are within the bounds + Column: + start column is within the bounds; + end column is after the bounds. This changes behaviour from previous versions of the protocol. Matching PRs in the emacs modes: + idris2-mode [PR#11](https://github.com/idris-community/idris2-mode/pull/11) + idris-mode [PR#547](https://github.com/idris-hackers/idris-mode/pull/547) ### Library changes #### Base * Adds `System.run`, which runs a shell command, and returns the stdout and return code of that run. * Adds escaped versions of `System.system`, `Systen.File.popen`, and `System.run`, which take a list of arguments, and escapes them. * Adds the `Injective` interface in module `Control.Function`. * Changes `System.pclose` to return the return code of the closed process. * Deprecates `base`'s `Data.Nat.Order.decideLTE` in favor of `Data.Nat.isLTE`. * Removes `base`'s deprecated `System.Directory.dirEntry`. Use `nextDirEntry` instead. * Removes `base`'s deprecated `Data.String.fastAppend`. Use `fastConcat` instead. * `System.File.Buffer.readBufferData` now returns the number of bytes that have been read into the buffer. #### Contrib * `System.Random` support for `Int` changed to `Int32`; it already limited itself to 32 bits but now that is codified. JavaScript backends are now supported. * Removes `contrib`'s deprecated `Data.Num.Implementations` module. See `Prelude.Interfaces` instead. ## v0.5.0/0.5.1 ### Language changes * Missing methods in implementations now give a compile time error. This was always the intended behaviour, but until now had not been implemented! * Records now work in `parameters` blocks and `where` clauses. * Implementations of interfaces now work in `parameters` blocks and `where` clauses * The syntax for Name reflection has changed, and now requires a single brace instead of a double brace, e.g. `` `{x} `` * Raw string literals allows writing string while customising the escape sequence. Start a string with `#"` in order to change the escape characters to `\#`, close the string with `"#`. Remains compatible with multiline string literals. * Interpolated strings allows inserting expressions within string literals and avoid writing concatenation explicitly. Escape a left curly brace `\{` to start an interpolation slice and close it with a right curly brace `}` to resume writing the string literal. The enclosed expression must be of type `String`. Interpolated strings are compatible with raw strings (the slices need to be escaped with `\#{` instead) and multiline strings. * We now support ellipses (written `_`) on the left hand side of a `with` clause. Ellipses are substituted for by the left hand side of the parent clause i.e. ```idris filter : (p : a -> Bool) -> List a -> List a filter p [] = [] filter p (x :: xs) with (p x) _ | True = x :: filter p xs _ | False = filter p xs ``` means ```idris filter : (p : a -> Bool) -> List a -> List a filter p [] = [] filter p (x :: xs) with (p x) filter p (x :: xs) | True = x :: filter p xs filter p (x :: xs) | False = filter p xs ``` ### Compiler changes * Added incremental compilation, using either the `--inc` flag or the `IDRIS2_INC_CGS` environment variable, which compiles modules incrementally. In incremental mode, the final build step is much faster than in whole program mode (the default), at the cost of runtime performance being about half as good. The `--whole-program` flag overrides incremental compilation, and reverts to whole program compilation. Incremental compilation is currently supported only by the Chez Scheme back end. This is currently supported only on Unix-like platforms (not yet Windows) - Note that you must set `IDRIS2_INC_CGS` when building and installing all libraries you plan to link with an incremental build. - Note also that this is experimental and not yet well tested! * The type checker now tries a lot harder to avoid reducing expressions where it is not needed. This can give a huge performance improvement in programs that potentially do a lot of compile time evaluation. However, sometimes reducing expressions can help in totality and quantity checking, so this may cause some programs not to type check which previously did - in these cases, you will need to give the reduced expressions explicitly. ### REPL/CLI/IDE mode changes * Added `--list-packages` CLI option. * Added `--total` CLI option. ### Library changes #### Prelude Changed - Removed `Data.Strings`. Use `Data.String` instead. #### System.Concurrency * Reimplement the `Channels` primitive in the Chez-Scheme backend since it had some non-deterministic properties (see issue [#1552](https://github.com/idris-lang/idris2/issues/1552)). NOTE: Due to complications with race-conditions, Chez not having channels built in, etc, the reimplementation changes the semantics slightly: `channelPut` no longer blocks until the value has been received under the `chez` backend, but instead only blocks if there is already a value in the channel that has not been received. With thanks to Alain Zscheile (@zseri) for help with understanding condition variables, and figuring out where the problems were and how to solve them. #### Control.Relation, Control.Order * The old system of interfaces for defining order relations (to say, for instance, that LTE is a partial order) is replaced with a new system of interfaces. These interfaces defines properties of binary relations (functions of type `ty -> ty -> Type`), and orders are defined simply as bundles of these properties. ### Installation changes * Added a new makefile target to install Idris 2 library documentation. After `make install`, type `make install-libdocs` to install it. After that, the index file can be found here: ``idris2 --libdir`/docs/index.html`.`` ## v0.4.0 ### Syntax changes * Desugar non-binding sequencing in do blocks to (`>>`) ([#1095](https://github.com/idris-lang/idris2/pull/1095)) * Multiline Strings with `"""` as delimiters ([#1097](https://github.com/idris-lang/idris2/pull/1097)) * Force strict indentation after usage of `with` keyword ([#1107](https://github.com/idris-lang/idris2/pull/1107)) * 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. * Add support for SnocList syntax: `[< 1, 2, 3]` desugars into `Lin :< 1 :< 2 :< 3` and their semantic highlighting. * Underscores can be used as visual separators for digit grouping purposes in integer literals: `10_000_000` is equivalent to `10000000` and `0b1111_0101_0000` is equivalent to `0b111101010000`. This can aid readability of long literals, or literals whose value should clearly separate into parts, such as bytes or words in hexadecimal notation. ### Compiler changes * Added more optimisations and transformations, particularly on case blocks, list-shaped types, and enumerations, so generated code will often be slightly faster. * Added `--profile` flag, which generates profile data if supported by a back end. Currently supported by the Chez and Racket backends. * 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)) * 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. * Added compiler warnings flags (`-W` prefix): - `-Wno-shadowing`: disable shadowing warnings. - `-Werror`: treat warnings as errors. * Experimental flag (`-Xcheck-hashes`) to check hashes instead of filesystem times to determine if files should be recompiled. Should help with CI/CD caching. ### 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 * Added a timeout to "generate definition" and "proof search" commands, defaulting to 1 second (1000 milliseconds) and configurable with `%search_timeout