# Changelog ## [Next version] ### Language changes * New magic constants `__LOC__`, `__FILE__`, `__LINE__`, `__COL__` substituted at parsing time with a string corresponding to the location, filename, line or column number associated to the magic constant's position. * The termination checker is now a faithful implementation of the 2001 paper on size-change termination by Lee, Jones and Ben-Amram. * New function option `%unsafe` to mark definitions that are escape hatches similar to the builtins `believe_me`, `assert_total`, etc. * Elaborator scripts were made be able to record warnings. * Rudimentary support for defining lazy functions (addressing issue [#1066](https://github.com/idris-lang/idris2/issues/1066)). * `%hide` directives can now hide conflicting fixities from other modules. ### REPL changes * Adds documentation for unquotes `~( )`. * Adds documentation for laziness and codata primitives: `Lazy`, `Inf`, `Delay`, and `Force`. ### Backend changes #### RefC * Adds support for `CFLAGS`, `CPPFLAGS`, and `LDFLAGS` to facilitate building on systems with non-standard installation locations of libraries (e.g. GMP). Versions of the flags with the `IDRIS2_` prefix can also be used and take precedence. #### Chez * Non-recursive top-level constants are compiled to eagerly evaluated constants in Chez Scheme. #### Node.js/Browser * Generated JavaScript files now include a shebang when using the Node.js backend * NodeJS now supports `popen`/`pclose` for the `Read` mode. * `getChar` is now supported on Node.js and `putChar` is supported on both JavaScript backends. * Integer-indexed arrays are now supported. ### Compiler changes * If `IAlternative` expression with `FirstSuccess` rule fails to typecheck, compiler now prints all tried alternatives, not only the last one. * The elaboration of records has been changed so that the unbound implicits in the parameters' types become additional parameters e.g. ```idris2 record HasLength (xs : List a) (n : Nat) where constructor MkHasLength 0 prf : length xs === n ``` is now correctly elaborated to ```idris2 record HasLength {0 a : Type} (xs : List a) (n : Nat) where constructor MkHasLength 0 prf : length xs === n ``` instead of failing with a strange error about (a) vs (a .rec). * Elaboration of datatypes now respects the totality annotations: defining a `covering` or `partial` datatype in a `%default total` file will not lead to a positivity error anymore. * Fixed a bug in the positivity checker that meant `Lazy` could be used to hide negative occurrences. * Made sure that the positivity checker now respects `assert_total` annotations. * We now raise a warning for conflicting fixity declarations. They are dangerous as Idris will pick an arbitrary one and so the meaning of an expression can depend e.g. on the order in which modules are imported. * Additionally some conflicting fixity declarations in the Idris 2 compiler and libraries have been removed. * Constructors mentioned on the left hand side of functions/case alternatives are now included in the `Refers to (runtime)` section of functions debug info. * The Lifted IR Representation now has a `HasNamespaces` implementation in `Compiler.Separate` so Compilation Units at that stage can be generated. * Added the `compile.casetree.missing` log topic, along with its use in `TTImp.ProcessDef.genRunTime`. This allows us to track when incomplete `case` blocks get the runtime error added. * Constant folding of trivial let statements and `believe_me`. * Fixed a bug that caused holes to appear unexpectedly during quotation of dependent pairs. ### Library changes #### Prelude * Improved performance of functions `isNL`, `isSpace`, and `isHexDigit`. * Implements `Foldable` and `Traversable` for pairs, right-biased as `Functor`. * Added a constructor (`MkInterpolation`) to `Interpolation`. * Added an `Interpolation` implementation for `Void`. * Added `Compose` instances for `Bifunctor`, `Bifoldable` and `Bitraversable`. #### Base * Deprecates `setByte` and `getByte` from `Data.Buffer` for removal in a future release. Use `setBits8` and `getBits8` instead (with `cast` if you need to convert a `Bits8` to an `Int`), as their values are limited, as opposed to the assumption in `setByte` that the value is between 0 and 255. * Adds RefC support for 16- and 32-bit access in `Data.Buffer`. * Add `Show` instance to `Data.Vect.Quantifiers.All` and add a few helpers for listy computations on the `All` type. * Add an alias for `HVect` to `All id` in `Data.Vect.Quantifiers.All`. This is the approach to getting a heterogeneous `Vect` of elements that is general preferred by the community vs. a standalone type as seen in `contrib`. * Add `Data.List.HasLength` from the compiler codebase slash contrib library but adopt the type signature from the compiler codebase and some of the naming from the contrib library. The type ended up being `HasLength n xs` rather than `HasLength xs n`. * `System`'s `die` now prints the error message on stderr rather than stdout * Moved `Data.SortedMap` and `Data.SortedSet` from contrib to base. * Added missing buffer primitives (chezscheme only): `setInt8`, `getInt8`, `getInt16`, `setInt64`, `getInt64` * Added new buffer (set/get) functions for built-in types `Bool`, `Nat`, `Integer`. * Tightened the types of: `setInt16` (now takes an `Int16` instead of an `Int`), `setInt32` (now takes an `Int32` instead of an `Int`), `getInt32` (now returns an `Int32` instead of an `Int`) * Adds left- and right-rotation for `FiniteBits`. * Adds `Vect.permute` for applying permutations to `Vect`s. * Adds `Vect.kSplits` and `Vect.nSplits` for splitting a `Vect` whose length is a known multiple of two `Nat`s (k * n) into k vectors of length n (and vice-versa). * Adds `Vect.allFins` for generating all the `Fin` elements as a `Vect` with matching length to the number of elements. * Add `withRawMode`, `enableRawMode`, `resetRawMode` for character at a time input on stdin. * Adds extraction functions to `Data.Singleton`. * `TTImp` reflection functions are now `public export`, enabling use at the type-level. * Implemented `Eq`, `Ord`, `Semigroup`, and `Monoid` for `Data.List.Quantifiers.All.All` and `Data.Vect.Quantifiers.All.All`. * Generalized `imapProperty` in `Data.List.Quantifiers.All.All` and `Data.Vect.Quantifiers.All.All`. * Add `zipPropertyWith` to `Data.Vect.Quantifiers.All.All`. * Implemented `Ord` for `Language.Reflection.TT.Name`, `Language.Reflection.TT.Namespace` and `Language.Reflection.TT.UserName`. * Adds `leftmost` and `rightmost` to `Control.Order`, a generalisation of `min` and `max`. #### System * Changes `getNProcessors` to return the number of online processors rather than the number of configured processors. * Adds `popen2` to run a subprocess with bi-directional pipes. ### Contrib * Adds `Data.List.Sufficient`, a small library defining a structurally inductive view of lists. * Remove `Data.List.HasLength` from `contrib` library but add it to the `base` library with the type signature from the compiler codebase and some of the naming from the `contrib` library. The type ended up being `HasLength n xs` rather than `HasLength xs n`. * Adds an implementation for `Functor Text.Lexer.Tokenizer.Tokenizer`. * Adds `modFin` and `strengthenMod` to `Data.Fin.Extra`. These functions reason about the modulo operator's upper bound, which can be useful when working with indices (for example). #### Papers * In `Control.DivideAndConquer`: a port of the paper `A Type-Based Approach to Divide-And-Conquer Recursion in Coq` by Pedro Abreu, Benjamin Delaware, Alex Hubers, Christa Jenkins, J. Garret Morris, and Aaron Stump ### Other Changes * The `data` subfolder of an installed or local dependency package is now automatically recognized as a "data" directory by Idris 2. See the [documentation on Packages](https://idris2.readthedocs.io/en/latest/reference/packages.html) for details. * The compiler no longer installs its own C support library into `${PREFIX}/lib`. This folder's contents were always duplicates of files installed into `${PREFIX}/idris2-${IDRIS2_VERSION}/lib`. If you need to adjust any tooling or scripts, point them to the latter location which still contains these installed library files. * Renamed `support-clean` Makefile target to `clean-support`. This is in line with most of the `install-` and `clean-` naming. ## v0.6.0 ### 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`. * Adds `:import`, with the same functionality as `:module`. * Adds the ability to request detailed help via `:help `, e.g. `:help :help` or `:help :let`. This also works with the `:?` and `:h` aliases. ### 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. * Adds a `failing` block that requires its body to fail with a compile error. Optionally this block may contain a string which is checked to be contained in the error message. * Bodies of `mutual`, `failing`, `using` and `parameters` blocks are required to be indented comparing to the position of the keyword. * `%nomangle` has been deprecated in favour of `%export`. * Records now support DataOpts, i.e. we can write things like ```idris record Wrap (phantom : Type) (a : Type) where [search a] -- this was previously not supported constructor MkWrap unWrap : a ``` * Adds ability to forward-declare interface implementations, e.g.: ```idris implementation IsOdd Nat -- forward declare for use in `IsEven` implementation IsEven Nat where isEven 0 = True isEven (S k) = not $ isOdd k implementation IsOdd Nat where isOdd 0 = False isOdd (S k) = not $ isEven k ``` * Adds ability to forward-declare records, e.g.: ```idris record B record A where b : B record B where a : A ``` ### 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`. * Alternatives for primitive types of the `Core.TT.Constant` are moved out to a separate data type `PrimTypes`. Signatures of functions that were working with `Constant` are changed to use `PrimTypes` when appropriate. * Codegens now take an additional `Ref Syn SyntaxInfo` argument. This empowers compiler writers to pretty print core terms e.g. to add comments with the original type annotations in the generated code. * `Refc.showcCleanStringChar` forgot some symbols which have now been added, ensuring the string is properly cleaned. * Constant-folds all casts and integral expressions (with the exception of type `Int`), leading to improved performance. * Increases accuracy of error reporting for keywords. * Adds the `eval.stuck.outofscope` log topic in order to be able to spot when we get stuck due to a function being out of scope. * Improves the error reporting for syntactically incorrect records. * `IPragma` now carries an `FC` with it for better error reporting. * Adds the number of enum constructors to enum types during codegen, to allow for trivial conversion to, e.g., `Bits32`. * Adds constant-folding for `Nat` literals. * Fixes `CyclicMeta` in `TTImp.ProcessDef` being considered a recoverable error. ### 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) * The IDE protocol now supports specifying a socket and hostname via the `--ide-mode-socket` flag, allowing multiple IDE server instances to run on the same machine. ### Interactive Editing changes * Case-split no longer generates syntactically invalid Idris when splitting on auto-implicits. * Case-split no longer shadows the function name when an internal named argument has the same name as the function. * Case-split now avoids using upper-case names for pattern variables. ### Library changes #### Prelude * `elemBy` and `elem` are now defined for any `Foldable` structure. The specialised versions defined in `Data.(List/SnocList/Vect)` have been removed. * `filter` and `mapMaybe` functions for `List` were moved to `prelude` from `base`. * Basic functions of `SnocList` (`(++)`, `length`, `filter`, `mapMaybe`) and implementations of `Eq` and `Ord` were moved to `prelude` from `base`. This may lead to a need to qualifying functions (e.g. `List.filter`) due to possible ambiguity. * "Fish" and "chips" operators of `SnocList` were moved to `Prelude.Types` from `Prelude.Basics`. * Adds `contra` for returning the opposite of a given `Ordering`. * Fix `pow`, using backend implementations. * Add `subtract` alias for `(-)` #### 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.writeBufferData` now returns the number of bytes that have been written when there is a write error. * `System.File.Buffer.readBufferData` now returns the number of bytes that have been read into the buffer. * Adds the `Data.List.Quantifiers.Interleaving` and `Data.List.Quantifiers.Split` datatypes, used for provably splitting a list into a list of proofs and a list of counter-proofs for a given property. * Properties of the `List1` type were moved from `Data.List1` to `Data.List1.Properties`. * `Syntax.PreorderReasoning` was moved to `base` from `contrib`. * Move the types and functions in `Data.Vect.Quantifiers` to their respective namespaces (`All` for all-related things, and `Any` for any-related things) to make the code consistent with the other quantifiers (`List` and `SnocList`). * Set the `all` and `any` functions for proof-quantifiers to `public export` instead of `export`, allowing them to be used with auto-implicit `IsYes`. * Legacy duplicating type `Given` (with constructor `Always`) is removed from the `Decidable.Decidable`. Use the type `IsYes` (with constructor `ItIsYes`) from the same module instead. * Adds `Data.List1.Elem`, ported from `Data.List.Elem`. * Adds `Data.List1.Quantifiers`, ported from `Data.List.Quantifiers`. * Changes the order of arguments in `RWST` transformer's runners functions (`runRWST`. `evalRWST`, `execRWST`), now transformer argument is the last, as in the other standard transformers, like `ReaderT` and `StateT`. * Adds `Data.Fin.finToNatEqualityAsPointwise`, which takes a witness of `finToNat k = finToNat l` and proves `k ~~~ l`. * Drop first argument (path to the `node` executable) from `System.getArgs` on the Node.js backend to make it consistent with other backends. * Adds `Uninhabited` instances for `FZ ~~~ FS k` and `FS k ~~~ FZ`. * Change behavior of `channelPut` on the Racket backend to match the behavior on the Chez backend. * `fGetLine` has been marked as `covering` instead of `total`. * Adds the ability to derive `Functor` and `Traversable` using `%runElab derive` in the implementation definition. * Fixes memory leaks in `currentDir`, `fGetLine`, and `fGetChars`. * Fixes `natToFinLT` being O(n) by proving that `So (x < n)` implies `LT x n`, allowing the compiler to optimise `natToFinLT` away. * Fixes `SnocList.foldr` and `SnocList.foldMap` to be performant and stack-safe. * Add `insertAt`, `deleteAt` and `replaceAt` for `List` * Add `scanr`, `scanr1` and `unsnoc` for `Vect` * Implement `DecEq` for `SnocList` #### Test * Refactors `Test.Golden.runTest` to use `System.Concurrency` from the base libraries instead of `System.Future` from `contrib`. In addition to reducing the dependency on `contrib` in the core of Idris2, this also seems to provide a small performance improvement for `make test`. * Splits `runner` into `runnerWith` for processing the options and configuring the test pools, and a new `runner` function for reading options from the command-line. #### 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. * Implements `Show tok => Show (ParsingError tok)` for `Text.Parser.Core`. * `Control.Linear.LIO` has been moved from `contribs` to `linear` to guarantee that idris2 does not need to rely on contribs anymore. #### Network * `Control.Linear.Network` now supports `connect` in the linear environment, and can also access the `sendBytes`, `recvBytes` and `recvAllBytes` functions of the underlying `Socket` module. #### Papers, Linear * Creates the `papers` and `linear` libraries to remove bits of type theory and pl propaganda from `contrib` and instead clearly have them as implementations of their respective papers. * Creates `Data.Linear.{Notation,LEither,LMaybe,LVect,Pow}`. * Moves `Data.Container`, based on the papers "Categories of Containers" by Michael Abbott, Thorsten Altenkirch, and Neil Ghani, and "Derivatives of Containers" by Michael Abbott, Thorsten Altenkirch, Neil Ghani, and Conor McBride, to `papers`. [https://doi.org/10.1007/3-540-36576-1_2](https://doi.org/10.1007/3-540-36576-1_2) [https://doi.org/10.1007/3-540-44904-3_2](https://doi.org/10.1007/3-540-44904-3_2) * Moves the implementation of "Indexed induction-recursion" by Dybjer and Setzer to `papers`. [https://doi.org/10.1016/j.jlap.2005.07.001](https://doi.org/10.1016/j.jlap.2005.07.001) * Ports "How to Take the Inverse of a Type" by Daniel Marshall and Dominic Orchard as `Data.Linear.{Communications,Diff,Inverse}`. [https://doi.org/10.4230/LIPIcs.ECOOP.2022.5](https://doi.org/10.4230/LIPIcs.ECOOP.2022.5) * Moves `Data.OpenUnion`, inspired by the paper "Freer monads, more extensible effects" by Oleg Kiselyov and Hiromi Ishii, to `papers`. [https://doi.org/10.1145/2887747.2804319](https://doi.org/10.1145/2887747.2804319) * Moves `Data.Recursion.Free`, partially based on "Turing-Completeness Totally Free" by Conor McBride, to `papers`. [https://doi.org/10.1007/978-3-319-19797-5_13](https://doi.org/10.1007/978-3-319-19797-5_13) * Moves `Data.Tree.Perfect` to `papers`. * Moves `Data.Vect.Binary`, taken from the paper "Heterogeneous Binary Random-access Lists" by Wouter Swierstra, to `papers`. [https://doi.org/10.1017/S0956796820000064](https://doi.org/10.1017/S0956796820000064) * Ports "Applications of Applicative Proof Search" by Liam O'Connor as `Search.{Generator,HDecidable,Negation,Properties,CTL,GCL}`. [https://doi.org/10.1145/2976022.2976030](https://doi.org/10.1145/2976022.2976030) * Implements "Dependent Tagless Final" by Nicolas Biri as `Language.Tagless`. [https://doi.org/10.1145/3498886.3502201](https://doi.org/10.1145/3498886.3502201) * Ports Todd Waugh Ambridge's Agda blog post series "Search over uniformly continuous decidable predicates on infinite collections of types" as `Search.Tychonoff`. [https://www.cs.bham.ac.uk/~txw467/tychonoff/InfiniteSearch1.html](https://www.cs.bham.ac.uk/~txw467/tychonoff/InfiniteSearch1.html) * Ports "Auto in Agda - Programming proof search using reflection" by Wen Kokke and Wouter Swierstra as `Search.Auto`. [https://doi.org/10.1007/978-3-319-19797-5_14](https://doi.org/10.1007/978-3-319-19797-5_14) * Ports "Computing with Generic Trees in Agda" by Stephen Dolan as `Data.W`. [https://doi.org/10.1145/3546196.3550165](https://doi.org/10.1145/3546196.3550165) ### Other changes * Adds docstrings for the lambda-lifted IR. * Package files are now installed along-side build artifacts for installed packages. This means all transitive dependencies of packages you specify with the `depends` field are added automatically. * No longer builds `contrib` and `papers` during bootstrap, as these may rely on new features not yet present in the bootstrap version of Idris2. ## 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