Changelog

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog and this project adheres to Semantic Versioning.

[0.13.2]

Added

New subcommand, futhark query, for looking up information about the name at some position in a file. Intended for editor integration.
(Finally) automatic support for compute model 7.5 in the CUDA backend.
Somewhat better performance for very large target arrays for reduce_by_index..

Removed

Changed

Fixed

Fixed a slice-iota simplification bug (#813).
Fixed defunctionalisation crash involving intrinsics (#814).

[0.13.1]

Added

Stack traces are now multiline for better legibility.

Changed

The empty(t) notation now specifies the type of the entire value (not just the element type), and requires dimension sizes when t is an array (e.g. empty(i32) is no longer allowed, you need for example empty([0]i32)).
All input files are now assumed to be in UTF-8.

Fixed

Fixed exponential-time behaviour for certain kernels with large arithmetic expressions (#805).
futhark test and friends no longer crash when reporting some errors (#808).
Fix uniqueness of loop results (#810).

[0.12.3]

Added

Character literals can now be any integer type.
The integer modules now have popc and clz functions.
Tweaked inlining so that larger programs may now compile faster (observed about 20%).
Pattern-matching on large sum typed-values taken from arrays may be a bit faster.

Fixed

Various small fixes to type errors.
All internal functions used in generated C code are now properly declared static.
Fixed bugs when handling dimensions and aliases in type ascriptions.

[0.12.2]

Added

New tool: futhark autotune, for tuning the threshold parameters used by incremental flattening. Based on work by Svend Lund Breddam, Simon Rotendahl, and Carl Mathias Graae Larsen.
New tool: futhark dataget, for extracting test input data. Most will probably never use this.
Programs compiled with the cuda backend now take options --default-group-size, --default-num-groups, and --default-tile-size.
Segmented reduce_by_index are now substantially fasted for small histograms.
New functions: f32.lerp and f64.lerp, for linear interpolation.

Fixed

Fixes to aliasing of record updates.
Fixed unnecessary array duplicates after coalescing optimisations.
reduce_by_index nested in maps will no longer sometimes require huge amounts of memory.
Source location now correct for unknown infix operators.
Function parameters are no longer in scope of themselves (#798).
Fixed a nasty out-of-bounds error in handling of irregular allocations.
The floor/ceil functions in f32/f64 now handle infinities correctly (and are also faster).
Using % on floats now computes fmod instead of crashing the compiler.

[0.12.1]

Added

The internal representation of parallel constructs has been overhauled and many optimisations rewritten. The overall performance impact should be neutral on aggregate, but there may be changes for some programs (please report if so).
Futhark now supports structurally typed sum types and pattern matching! This work was done by Robert Schenck. There remain some problems with arrays of sum types that themselves contain arrays.
Significant reduction in compile time for some large programs.
Manually specified type parameters need no longer be exhaustive.
Mapped rotate is now simplified better. This can be particularly helpful for stencils with wraparound.

Removed

The ~ prefix operator has been removed. ! has been extended to perform bitwise negation when applied to integers.

Changed

The --futhark option for futhark bench and futhark test now defaults to the binary being used for the subcommands themselves.
The legacy futhark -t option (which did the same as futhark check) has been removed.
Lambdas now bind less tightly than type ascription.
stream_map is now map_stream and stream_red is now reduce_stream.

Fixed

futhark test now understands --no-tuning as it was always supposed to.
futhark bench and futhark test now interpret --exclude in the same way.
The Python and C# backends can now properly read binary boolean input.

[0.11.2]

Fixed

Entry points whose types are opaque due to module ascription, yet whose representation is simple (scalars or arrays of scalars) were mistakely made non-opaque when compiled with --library. This has been fixed.
The CUDA backend now supports default sizes in .tuning files.
Loop interchange across multiple dimensions was broken in some cases (#767).
The sequential C# backend now generates code that compiles (#772).
The sequential Python backend now generates code that runs (#765).

[0.11.1]

Added

Segmented scans are a good bit faster.
reduce_by_index has received a new implementation that uses local memory, and is now often a good bit faster when the target array is not too large.
The f32 and f64 modules now contain gamma and lgamma functions. At present these do not work in the C# backend.
Some instances of reduce with vectorised operators (e.g. map2 (+)) are orders of magnitude faster than before.
Memory usage is now lower on some programs (specifically the ones that have large maps with internal intermediate arrays).

Removed

Size parameters (not annotations) are no longer permitted directly in let and loop bindings, nor in lambdas. You are likely not affected (except for the stream constructs; see below). Few people used this.

Changed

The array creation functions exported by generated C code now take int64_t arguments for the shape, rather than int. This is in line with what the shape functions return.
The types for stream_map, stream_map_per, stream_red, and stream_red_per have been changed, such that the chunk function now takes the chunk size as the first argument.

Fixed

Fixes to reading values under Python 3.
The type of a variable can now be deduced from its use as a size annotation.
The code generated by the C-based backends is now also compilable as C++.
Fix memory corruption bug that would occur on very large segmented reductions (large segments, and many of them).

[0.10.2]

Added

reduce_by_index is now a good bit faster on operators whose arguments are two 32-bit values.
The type checker warns on size annotations for function parameters and return types that will not be visible from the outside, because they refer to names nested inside tuples or records. For example, the function
```
let f (n: i32, m: i32): [n][m]i32 = ...
```
will cause such a warning. It should instead be written
```
let f (n: i32) (m: i32): [n][m]i32 = ...
```
A new library function futhark_context_config_select_device_interactively() has been added.

Fixed

Fix reading and writing of binary files for C-compiled executables on Windows.
Fixed a couple of overly strict internal sanity checks related to in-place updates (#735, #736).
Fixed a couple of convoluted defunctorisation bugs (#739).

[0.10.1]

Added

Using definitions from the intrinsic module outside the prelude now results in a warning.
reduce_by_index with vectorised operators (e.g. map2 (+)) is orders of magnitude faster than before.
Executables generated with the pyopencl backend now support the options --default-tile-size, --default-group-size, --default-num-groups, --default-threshold, and --size.
Executables generated with c and opencl now print a help text if run with invalid options. The py and pyopencl backends already did this.
Generated executables now support a --tuning flag for passing many tuned sizes in a file.
Executables generated with the cuda backend now take an --nvrtc-option option.
Executables generated with the opencl backend now take a --build-option option.

Removed

The old futhark-* executables have been removed.

Changed

If an array is passed for a function parameter of a polymorphic type, all arrays passed for parameters of that type must have the same shape. For example, given a function
```
let pair 't (x: t) (y: t) = (x, y)
```
The application pair [1] [2,3] will now fail at run-time.
futhark test now numbers un-named data sets from 1 rather than 0. This only affects the text output and the generated JSON files, and fits the tuple element ordering in Futhark.
String literals are now of type []u8 and contain UTF-8 encoded bytes.

Fixed

An significant problematic interaction between empty arrays and inner size declarations has been closed (#714). This follows a range of lesser empty-array fixes from 0.9.1.
futhark datacmp now prints to stdout, not stderr.
Fixed a major potential out-of-bounds access when sequentialising reduce_by_index (in most cases the bug was hidden by subsequent C compiler optimisations).
The result of an anonymous function is now also forbidden from aliasing a global variable, just as with named functions.
Parallel scans now work correctly when using a CPU OpenCL implementation.
reduce_by_index was broken on newer NVIDIA GPUs when using fancy operators. This has been fixed.

[0.9.1]

Added

futhark cuda: a new CUDA backend by Jakob Stokholm Bertelsen.
New command for comparing data files: futhark datacmp.
An :mtype command for futhark repl that shows the type of a module expression.
futhark run takes a -w option for disabling warnings.

Changed

Major command reorganisation: all Futhark programs have been combined into a single all-powerful futhark program. Instead of e.g. futhark-foo, use futhark foo. Wrappers will be kept around under the old names for a little while. futharki has been split into two commands: futhark repl and futhark run. Also, py has become python and cs has become csharp, but pyopencl and csopencl have remained as they were.
The result of a function is now forbidden from aliasing a global variable. Surprisingly little code is affected by this.
A global definition may not be ascribed a unique type. This never had any effect in the first place, but now the compiler will explicitly complain.
Source spans are now printed in a slightly different format, with ending the line number omitted when it is the same as the start line number.

Fixed

futharki now reports source locations of trace expressions properly.
The type checker now properly complains if you try to define a type abbreviation that has unused size parameters.

[0.8.1]

Added

Now warns when /futlib/... files are redundantly imported.
futharki now prints warnings for files that are ":load"ed.
The compiler now warns when entry points are declared with types that will become unnamed and opaque, and thus impossible to provide from the outside.
Type variables invented by the type checker will now have a unicode subscript to distinguish them from type parameters originating in the source code.
futhark-test and futhark-bench now support generating random test data.
The library backends now generate proper names for arrays of opaque values.
The parser now permits empty programs.
Most transpositions are now a good bit faster, especially on NVIDIA GPUs.

Removed

The <- symbol can no longer be used for in-place updates and record updates (deprecated in 0.7.3).

Changed

Entry points that accept a single tuple-typed parameter are no longer silently rewritten to accept multiple parameters.

Fixed

The :type command in futharki can now handle polymorphic expressions (#669).
Fixed serious bug related to chaining record updates.
Fixed type inference of record fields (#677).
futharki no longer goes in an infinite loop if a for loop contains a negative upper bound.
Overloaded number types can no longer carry aliases (#682).

[0.7.4]

Added

Support type parameters for operator specs defined with val.

Fixed

Fixed nasty defunctionalisation bug (#661).
cabal sdist and stack sdist works now.

[0.7.3]

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.

[0.7.2]

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.

[0.7.1]

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.

[0.6.3]

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).

[0.6.2]

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).

[0.6.1]

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.

[0.5.2]

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).

[0.5.1]

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.

[0.4.1]

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).

[0.4.0]

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).

[0.3.1]

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).

[0.3.0]

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.

[0.2.0]

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.

[0.1.0]

(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".

Files

CHANGELOG.md

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Changelog

[0.13.2]

Added

Removed

Changed

Fixed

[0.13.1]

Added

Changed

Fixed

[0.12.3]

Added

Fixed

[0.12.2]

Added

Fixed

[0.12.1]

Added

Removed

Changed

Fixed

[0.11.2]

Fixed

[0.11.1]

Added

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Changed

Fixed

[0.10.2]

Added

Fixed

[0.10.1]

Added

Removed

Changed

Fixed

[0.9.1]

Added

Changed

Fixed

[0.8.1]

Added

Removed

Changed

Fixed

[0.7.4]

Added

Fixed

[0.7.3]

Added

Fixed

[0.7.2]

Added

Fixed

[0.7.1]

Added

Removed

Changed

Fixed

[0.6.3]

Added

Fixed

[0.6.2]

Added

Fixed

[0.6.1]

Added

Removed

Changed

Fixed

[0.5.2]

Added

Fixed

[0.5.1]