futhark

Added

• Support type parameters for operator specs defined with val.

Fixed

• Fixed nasty defunctionalisation bug (#661).

• cabal/stack sdist works now.

Added

• Significant performance changes: there is now a constant extra
  compilation overhead (less than 200ms on most machines). However,
  the rest of the compiler is 30-40% faster (or more in some cases).

• A warning when ambiguously typed expressions are assigned a
  default (i32 or f64).

• In-place updates and record updates are now written with =
  instead of <-. The latter is deprecated and will be removed in
  the next major version (#650).

Fixed

• Polymorphic value bindings now work properly with module type
  ascription.

• The type checker no longer requires types used inside local
  functions to be unambiguous at the point where the local function
  is defined. They must still be unambiguous by the time the
  top-level function ends. This is similar to what other ML
  languages do.

• futhark-bench now writes "μs" instead of "us".

• Type inference for infix operators now works properly.

Added

• futhark-pkg now supports GitLab.

• futhark-tests --notty option now has a --no-terminal alias.
  --notty is deprecated, but still works.

• futhark-test now supports multiple entry points per test block.

• Functional record updates: r with f <- x.

Fixed

• Fix the -C option for futhark-test.

• Fixed incorrect type of reduce_by_index.

• Segmented reduce_by_index now uses much less memory.

Added

• C# backend by Mikkel Storgaard Knudsen (futhark-cs/futhark-csopencl).

• futhark-test and futhark-bench now take a --runner option.

• futharki now uses a new interpreter that directly interprets the
  source language, rather than operating on the desugared core
  language. In practice, this means that the interactive mode is
  better, but that interpretation is also much slower.

• A trace function that is semantically id, but makes futharki
  print out the value.

• A break function that is semantically id, but makes futharki
  stop and provide the opportunity to inspect variables in scope.

• A new SOAC, reduce_by_index, for expressing generalised
  reductions (sometimes called histograms). Designed and
  implemented by Sune Hellfritzsch.

Removed

• Most of futlib has been removed. Use external packages instead:

  • futlib/colour => https://github.com/athas/matte

  • futlib/complex => https://github.com/diku-dk/complex

  • futlib/date => https://github.com/diku-dk/date

  • futlib/fft => https://github.com/diku-dk/fft

  • futlib/linalg => https://github.com/diku-dk/fft

  • futlib/merge_sort, futlib/radix_sort => https://github.com/diku-dk/sorts

  • futlib/random => https://github.com/diku-dk/cpprandom

  • futlib/segmented => https://github.com/diku-dk/segmented

  • futlib/sobol => https://github.com/diku-dk/sobol

  • futlib/vector => https://github.com/athas/vector

  No replacement: futlib/mss, futlib/lss.

• zip6/zip7/zip8 and their unzip variants have been removed.
  If you build gigantic tuples, you're on your own.

• The >>> operator has been removed. Use an unsigned integer type
  if you want zero-extended right shifts.

Changed

• The largest/smallest values for numeric modules have been
  renamed highest/lowest.

Fixed

• Many small things.

Added

• Added a package manager: futhark-pkg. See also the
  documentation.

• Added log2 and log10 functions to f32 and f64.

• Module type refinement (with) now permits refining parametric
  types.

• Better error message when invalid values are passed to generated
  Python entry points.

• futhark-doc now ignores files whose doc comment is the word
  "ignore".

• copy now works on values of any type, not just arrays.

• Better type inference for array indexing.

Fixed

• Floating-point numbers are now correctly rounded to nearest even
  integer, even in exotic cases (#377).

• Fixed a nasty bug in the type checking of calls to consuming
  functions (#596).

Added

• Bounds checking errors now show the erroneous index and the size
  of the indexed array. Some other size-related errors also show
  more information, but it will be a while before they are all
  converted (and say something useful - it's not entirely
  straightforward).

• Opaque types now have significantly more readable names,
  especially if you add manual size annotations to the entry point
  definitions.

• Backticked infix operators can now be used in operator sections.

Fixed

• f64.e is no longer pi.

• Generated C library code will no longer abort() on application
  errors (#584).

• Fix file imports on Windows.

• futhark-c and futhark-opencl now generates thread-safe code (#586).

• Significantly better behaviour in OOM situations.

• Fixed an unsound interaction between in-place updates and
  parametric polymorphism (#589).

Added

• The real module type now specifies tan.

• futharki now supports entering declarations.

• futharki now supports a :type command (or :t for short).

• futhark-test and futhark-benchmark now support gzipped data
  files. They must have a .gz extension.

• Generated code now frees memory much earlier, which can help
  reduce the footprint.

• Compilers now accept a --safe flag to make them ignore unsafe.

• Module types may now define lifted abstract types, using the
  notation type ^t. These may be instantiated with functional
  types. A lifted abstract type has all the same restrictions as a
  lifted type parameter.

Removed

• The rearrange construct has been removed. Use transpose instead.

• futhark-mode.el has been moved to a separate
  repository.

• Removed |>> and <<|. Use >-> and <-< instead.

• The empty construct is no longer supported. Just use empty
  array literals.

Changed

• Imports of the basis library must now use an absolute path
  (e.g. /futlib/fft, not simply futlib/fft).

• /futlib/vec2 and /futlib/vec3 have been replaced by a new
  /futlib/vector file.

• Entry points generated by the C code backend are now prefixed with
  futhark_entry_ rather than just futhark_.

• zip and unzip are no longer language constructs, but library
  functions, and work only on two arrays and pairs, respectively.
  Use functions zipN/unzipN (for 2<=n<=8).

Fixed

• Better error message on EOF.

• Fixed handling of .. in import paths.

• Type errors (and other compiler feedback) will no longer contain
  internal names.

• futhark-test and friends can now cope with infinities and NaNs.
  Such values are printed and read as f32.nan, f32.inf,
  -f32.inf, and similarly for f32. In futhark-test, NaNs
  compare equal.

Added

• Array index section: (.[i]) is shorthand for (\x -> x[i]).
  Full slice syntax supported. (#559)

• New assert construct. (#464)

• futhark-mode.el now contains a definition for flycheck.

Fixed

• The index produced by futhark-doc now contains correct links.

• Windows linebreaks are now fully supported for test files (#558).

Added

• Entry points need no longer be syntactically first-order.

• Added overloaded numeric literals (#532). This means type
  suffixes are rarely required.

• Binary and unary operators may now be bound in patterns by
  enclosing them in parenthesis.

• futhark-doc now produces much nicer documentation. Markdown is
  now supported in documentation comments.

• /futlib/functional now has operators >-> and <-< for
  function composition. <<| are |>> are deprecated.

• /futlib/segmented now has a segmented_reduce.

• Scans and reductions can now be horizontally fused.

• futhark-bench now supports multiple entry points, just like
  futhark-test.

• ".." is now supported in include paths.

Removed

• The reshape construct has been removed. Use the
  flatten/unflatten functions instead.

• concat and rotate no longer support the @ notation. Use
  map nests instead.

• Removed -I/--library. These never worked with
  futhark-test/futhark-bench anyway.

Changed

• When defining a module type, a module of the same name is no
  longer defined (#538).

• The default keyword is no longer supported.

• /futlib/merge_sort and /futlib/radix_sort now define
  functions instead of modules.

Fixed

• Better type inference for rearrange and rotate.

• import path resolution is now much more robust.

Added

• Unused-result elimination for reductions; particularly useful when
  computing with dual numbers for automatic differentiation.

• Record field projection is now possible for variables of (then)
  unknown types. A function parameter must still have an
  unambiguous (complete) type by the time it finishes checking.

Fixed

• Fixed interaction between type ascription and type inference (#529).

• Fixed duplication when an entry point was also called as a function.

• Futhark now compiles cleanly with GHC 8.4.1 (this is also the new default).

Added

• The constructor for generated PyOpenCL classes now accepts a
  command_queue parameter (#480).

• Transposing small arrays is now much faster when using OpenCL
  backend (#478).

• Infix operators can now be defined in prefix notation, e.g.:

  let (+) (x: i32) (y: i32) = x - y
  

  This permits them to have type- and shape parameters.

• Comparison operators (<=, <, >, >=) are now valid for boolean
  operands.

• Ordinary functions can be used as infix by enclosing them in
  backticks, as in Haskell. They are left-associative and have
  lowest priority.

• Numeric modules now have largest/smallest values.

• Numeric modules now have sum, product, maximum, and
  minimum functions.

• Added --Werror command line option to compilers.

• Higher-order functions are now supported (#323).

• Type inference is now supported, although with some limitations
  around records, in-place updates, and unzip. (#503)

• Added a range of higher-order utility functions to the prelude,
  including (among others):

  val (|>) '^a '^b: a ->  (a -> b) -> b
  
  val (<|) '^a '^b: (a -> b) -> a -> b
  
  val (|>>) '^a 'b '^c: (a -> b) -> (b -> c) -> a -> c
  
  val (<<|) '^a 'b '^c: (b -> c) -> (a -> b) a -> c
  

Changed

• FUTHARK_VERSIONED_CODE is now FUTHARK_INCREMENTAL_FLATTENING.

• The SOACs map, reduce, filter, partition, scan,
  stream_red, and stream_map have been replaced with library
  functions.

• The futlib/mss and futlib/lss modules have been rewritten to use
  higher-order functions instead of modules.

Fixed

• Transpositions in generated OpenCL code no longer crashes on
  large but empty arrays (#483).

• Booleans can now be compared with relational operators without
  crashing the compiler (#499).

Added

• futhark-bench now tries to align benchmark results for better
  legibility.

Fixed

• futhark-test: now handles CRLF linebreaks correctly (#471).

• A record field can be projected from an array index expression (#473).

• Futhark will now never automatically pick Apple's CPU device for
  OpenCL, as it is rather broken. You can still select it
  manually (#475).

• Fixes to set_bit functions in the math module (#476).

Added

• A comprehensible error message is now issued when attempting to
  run a Futhark program on an OpenCL that does not support the
  types used by the program. A common case was trying to use
  double-precision floats on an Intel GPU.

• Parallelism inside of a branch can now be exploited if the branch
  condition and the size of its results is invariant to all
  enclosing parallel loops.

• A new OpenCL memory manager can in some cases dramatically
  improve performance for repeated invocations of the same entry
  point.

• Experimental support for incremental flattening. Set the
  environment variable FUTHARK_VERSIONED_CODE to any value to try
  it out.

• futhark-dataset: Add -t/-type option. Useful for
  inspecting data files.

• Better error message when ranges written with two dots
  (x..y).

• Type errors involving abstract types from modules now use
  qualified names (less "expected 't', got 't'", more "expected
  'foo.t', got 'bar.t'").

• Shorter compile times for most programs.

• futhark-bench: Add --skip-compilation flag.

• scatter expressions nested in maps are now parallelised.

• futlib: an fft module has been added, thanks to David
  P.H. Jørgensen and Kasper Abildtrup Hansen.

Removed

• futhark-dataset: Removed --binary-no-header and
  --binary-only-header options.

• The split language construct has been removed. There is a
  library function split that does approximately the same.

Changed

• futlib: the complex module now produces a non-abstract complex
  type.

• futlib: the random module has been overhauled, with several new
  engines and adaptors changed, and some of the module types
  changed. In particular, rng_distribution now contains a numeric
  module instead of an abstract type.

• futlib: The vec2 and vec3 modules now represent vectors as
  records rather than tuples.

• futlib: The linalg module now has distinct convenience functions
  for multiplying matrices with row and column vectors.

• Only entry points defined directly in the file given to the
  compiler will be visible.

• Range literals are now written without brackets: x...y.

• The syntax (-x) can no longer be used for a partial application
  of subtraction.

• futhark-test and futhark-bench will no longer append .bin to
  executables.

• futhark-test and futhark-bench now replaces actual/expected
  files from previous runs, rather than increasing the litter.

Fixed

• Fusion would sometimes remove safety checks on e.g. reshape
  (#436).

• Variables used as implicit fields in a record construction are now
  properly recognised as being used.

• futlib: the num_bits field for the integer modules in math now
  have correct values.

Added

• Run-time errors due to failed assertions now include a stack
  trace.

• Generated OpenCL code now picks more sensible group size and count
  when running on a CPU.

• scatter expressions nested in maps may now be parallelised
  ("segmented scatter").

• Add num_bits/get_bit/set_bit functions to numeric module
  types, including a new float module type.

• Size annotations may now refer to preceding parameters, e.g:

  let f (n: i32) (xs: [n]i32) = ...
  

• futhark-doc: retain parameter names in generated docs.

• futhark-doc: now takes -v/--verbose options.

• futhark-doc: now generates valid HTML.

• futhark-doc: now permits files to contain a leading documentation
  comment.

• futhark-py/futhark-pyopencl: Better dynamic type checking in
  entry points.

• Primitive functions (sqrt etc) can now be constant-folded.

• Futlib: /futlib/vec2 added.

Removed

• The built-in shape function has been removed. Use length or
  size parameters.

Changed

• The from_i32/from_i64 functions of the numeric module type
  have been replaced with functions named i32/i64. Similarly
  functions have been added for all the other primitive types
  (factored into a new from_prim module type).

• The overloaded type conversion functions (i32, f32, bool,
  etc) have been removed. Four functions have been introduced for
  the special cases of converting between f32/f64 and i32:
  r32, r64, t32, t64.

• Modules and variables now inhabit the same name space. As a
  consequence, we now use x.y to access field y of record x.

• Record expression syntax has been simplified. Record
  concatenation and update is no longer directly supported.
  However, fields can now be implicitly defined: {x,y} now creates
  a record with field x and y, with values taken from the
  variables x and y in scope.

Fixed

• The != operator now works properly on arrays (#426).

• Allocations were sometimes hoisted incorrectly (#419).

• f32.e is no longer pi.

• Various other fixes.

(This is just a list of highlights of what was included in the first
release.)

• Code generators: Python and C, both with OpenCL.

• Higher-order ML-style module system.

• In-place updates.

• Tooling: futhark-test, futhark-bench, futhark-dataset, futhark-doc.

• Beginnings of a basis library, "futlib".