Idris2/CHANGELOG.md
2020-12-03 15:28:20 +03:00

7.7 KiB

Changes since Idris 2 v0.2.1

Library changes:

  • Added Data.HVect in contrib, for heterogeneous vectors.

Command-line options changes:

  • Added --color and --no-color options for colored terminal output. Color is enabled by default.
  • Added --console-width <auto|n> 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.

Compiler changes:

  • Added new syntax for named applications and the bind-all-explicits pattern:

    f {x [= t], x [= t], ...} f {x [= t], x [= t], ..., _} f {}

  • Added new syntax for record updates:

    {x := t, x $= t, ...}

  • Added primitives to the parsing library used in the compiler to get more precise boundaries to the AST nodes FC.

  • New experimental refc code generator, which generates C with reference counting.

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 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.
  • 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 or build from the generated Scheme, using make bootstrap.

Language changes:

  • total, covering and partial flags on functions now have an effect.
  • %default <totality status> 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 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 <term> or with [NS.name1, NS.name2, ...] <term> to disable disambiguation for the given names in <term>. 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: https://idris2.readthedocs.io/en/latest/reference/literate.html

Changes since Idris 1

Everything :). For full details, see: https://idris2.readthedocs.io/en/latest/updates/updates.html