https://github.com/JuliaLang/julia
Tip revision: 0030eec2f332f353e6890ca289ac2aca55532dde authored by Tony Kelman on 26 July 2016, 20:10:23 UTC
Bump VERSION to 0.5.0-rc0
Bump VERSION to 0.5.0-rc0
Tip revision: 0030eec
NEWS.md
Julia v0.5.0 Release Notes
==========================
New language features
---------------------
* Generator expressions: `f(i) for i in 1:n` ([#4470]). This returns an iterator
that computes the specified values on demand. This is useful for computing, e.g.
`sum(f(i) for i in 1:n)` without creating an intermediate array of values.
* Generators and comprehensions support filtering using `if` ([#550]) and nested
iteration using multiple `for` keywords ([#4867]).
* Fused broadcasting syntax: ``f.(args...)`` is equivalent to ``broadcast(f, args...)`` ([#15032]),
and nested `f.(g.(args...))` calls are fused into a single `broadcast` loop ([#17300]).
Similarly, the syntax `x .= ...` is equivalent to a `broadcast!(identity, x, ...)`
call and fuses with nested "dot" calls; also, `x .+= y` and similar is now
equivalent to `x .= x .+ y`, rather than `x = x .+ y` ([#17510]).
* Macro expander functions are now generic, so macros can have multiple definitions
(e.g. for different numbers of arguments, or optional arguments) ([#8846], [#9627]).
However note that the argument types refer to the syntax tree representation, and not
to the types of run time values.
* Varargs functions like `foo{T}(x::T...)` may now restrict the number
of such arguments using `foo{T,N}(x::Vararg{T,N})` ([#11242]).
* `x ∈ X` is now a synonym for `x in X` in `for` loops and comprehensions,
as it already was in comparisons ([#13824]).
* The `PROGRAM_FILE` global is now available for determining the name of the running script ([#14114]).
* The syntax `x.:sym` (e.g. `Base.:+`) is now supported, and `x.(:sym)` is deprecated ([#15032]).
* Function return type syntax `function f()::T` has been added ([#1090]). Values returned
from a function with such a declaration will be converted to the specified type `T`.
* Experimental support for arrays with indexing starting at values
different from 1. The array types are expected to be defined in
packages, but now Julia provides an API for writing generic
algorithms for arbitrary indexing schemes ([#16260]).
* Many more operators now support `.` prefixes (e.g. `.≤`) ([#17393]). However,
users are discouraged from overloading these, since they are mainly parsed
in order to implement backwards compatibility with planned automatic
broadcasting of dot operators in Julia 0.6 ([#16285]). Explicitly qualified
operator names like `Base.≤` should now use `Base.:≤` (prefixed by `@compat`
if you need 0.4 compatibility via the `Compat` package).
Language changes
----------------
* Each function and closure now has its own type. The captured variables of a closure
are fields of its type. `Function` is now an abstract type, and is the default supertype
of functions and closures. All functions, including anonymous functions,
are generic and support all features (e.g. keyword arguments).
Instead of adding methods to `call`, methods are added by type using the syntax
`(::ftype)(...) = ...`. `call` is deprecated ([#13412]).
* `using` and `import` are now case-sensitive even on case-insensitive filesystems
(common on Mac and Windows) ([#13542]).
* Relational algebra symbols are now allowed as infix operators ([#8036]):
`⨝`, `⟕`, `⟖`, `⟗` for joins and `▷` for anti-join.
* A warning is always given when a method is overwritten (previously, this was done
only when the new and old definitions were in separate modules) ([#14759]).
* The `if` keyword cannot be followed immediately by a line break ([#15763]).
* Juxtaposition of numeric literals ending in `.` (e.g. `1.x`) is no longer
allowed ([#15731]).
* The built-in `NTuple` type has been removed; `NTuple{N,T}` is now
implemented internally as `Tuple{Vararg{T,N}}` ([#11242]).
* Use of the syntax `x::T` to declare the type of a local variable is deprecated.
In the future this will always mean type assertion, and declarations should use
`local x::T` instead ([#16071]).
When `x` is global, `x::T = ...` and `global x::T` used to mean type assertion,
but this syntax is now reserved for type declaration ([#964]).
Command-line option changes
---------------------------
Compiler/Runtime improvements
-----------------------------
* Machine SIMD types can be represented in Julia as a homogeneous tuple of `VecElement` ([#15244]).
New architectures
-----------------
This release greatly improves support for ARM, and introduces support for Power.
* [ARM](https://github.com/JuliaLang/julia/issues?utf8=%E2%9C%93&q=label%3Aarm):
[#14194], [#14519], [#16645], [#16621]
* [Power](https://github.com/JuliaLang/julia/issues?utf8=%E2%9C%93&q=label%3Apower):
[#16455], [#16404]
Breaking changes
----------------
This section lists changes that do not have deprecation warnings.
* The assignment operations `.+=`, `.*=` and so on now generate calls
to `broadcast!` on the left-hand side (or call to `view(a, ...)` on the left-hand side
if the latter is an indexing expression, e.g. `a[...]`). This means that they will fail
if the left-hand side is immutable (or does not support `view`), and will otherwise
change the left-hand side in-place ([#17510], [#17546]).
* Method ambiguities no longer generate warnings when files are loaded,
nor do they dispatch to an arbitrarily-chosen method; instead, a call that
cannot be resolved to a single method results in a `MethodError` at run time,
rather than the previous definition-time warning. ([#6190])
* Array comprehensions preserve the dimensions of the input ranges. For example,
`[2x for x in A]` will have the same dimensions as `A` ([#16622]).
* The result type of an array comprehension depends only on the types of elements
computed, instead of using type inference ([#7258]). If the result is empty, then
type inference is still used to determine the element type.
* `reshape` is now defined to always share data with the original array.
If a reshaped copy is needed, use `copy(reshape(a))` or `copy!` to a new array of
the desired shape ([#4211]).
* `mapslices` now re-uses temporary storage. Recipient functions that expect
input slices to be persistent should copy data to other storage ([#17266]).
All usages of `mapslices` should be carefully audited since this change can cause
silent, incorrect behavior, rather than failing noisily.
* Local variables and arguments are represented in lowered code as numbered `Slot`
objects instead of as symbols ([#15609]).
* The information that used to be in the `ast` field of the `LambdaStaticData` type
is now divided among the fields `code`, `slotnames`, `slottypes`, `slotflags`,
`gensymtypes`, `rettype`, `nargs`, and `isva` in the `LambdaInfo` type ([#15609]).
* `A <: B` is parsed as `Expr(:(<:), :A, :B)` in all cases ([#9503]).
This also applies to the `>:` operator.
* Simple 2-argument comparisons like `A < B` are parsed as calls instead of using the
`:comparison` expression type ([#15524]). The `:comparison` expression type is still
produced in ASTs when comparisons are chained (e.g. `A < B ≤ C`).
Library improvements
--------------------
* Strings ([#16107]):
* The `UTF8String` and `ASCIIString` types have been merged into a single
`String` type ([#16058]). Use `isascii(s)` to check whether
a string contains only ASCII characters. The `ascii(s)` function now
converts `s` to `String`, raising an `ArgumentError` exception if `s` is
not pure ASCII.
* The `UTF16String` and `UTF32String` types and corresponding `utf16` and
`utf32` converter functions have been removed from the standard library.
If you need these types, they have been moved to the
[LegacyStrings](https://github.com/JuliaArchive/LegacyStrings.jl)
package. In the future, more robust Unicode string support will be provided
by the `StringEncodings` package. If you only need these types to call wide
string APIs (UTF-16 on Windows, UTF-32 on UNIX), consider using the new
`transcode` function (see below) or the `Cwstring` type as a `ccall` argument
type, which also ensures correct NUL termination of string data.
* The basic string construction routines are now `string(args...)`,
`String(s)`, `unsafe_string(ptr)` (formerly `bytestring(ptr)`), and
`unsafe_wrap(String, ptr)` (formerly `pointer_to_string`) ([#16731]).
* A `transcode(T, src)` function is now exported for converting data
between UTF-xx Unicode encodings ([#17323]).
* Comparisons between `Char`s and `Integer`s are now deprecated ([#16024]):
`'x' == 120` now produces a warning but still evaluates to `true`. In the
future it may evaluate to `false` or the comparison may be an error. To
compare characters with integers you should either convert the integer to
a character value or convert the character to the corresponding code point
first: e.g. `'x' == Char(120)` or `Int('x') == 120`. The former is usually
preferable.
* Support for Unicode 9 ([#17402]).
* Packages:
* The package system (`Pkg`) is now based on the `libgit2` library, rather
than running the `git` program, increasing performance (especially on
Windows) ([#11196]).
* Package-development functions like `Pkg.tag` and `Pkg.publish`
have been moved to an external [PkgDev] package ([#13387]).
* Updating only a subset of the packages is now supported,
e.g. `Pkg.update("Example")` ([#17132])
* The `Base.Test` module now has a `@testset` feature to bundle
tests together and delay throwing an error until the end ([#13062]).
* The new features are mirrored in the
[BaseTestNext](https://github.com/IainNZ/BaseTestNext.jl)
package for users who would like to use the new functionality on Julia v0.4.
* The [BaseTestDeprecated](https://github.com/IainNZ/BaseTestDeprecated.jl)
package provides the old-style `handler` functionality, for compatibility
with code that needs to support both Julia v0.4 and v0.5.
* Most of the combinatorics functions have been moved from `Base`
to the [Combinatorics.jl package](https://github.com/JuliaLang/Combinatorics.jl) ([#13897]).
* `pmap` keyword arguments `err_retry=true` and `err_stop=false` are deprecated.
Action to be taken on errors can be specified via the `on_error` keyword argument.
Retry is specified via `retry_n`, `retry_on` and `retry_max_delay` ([#15409], [#15975], [#16663]).
* The functions `remotecall`, `remotecall_fetch`, and `remotecall_wait` now have the
function argument as the first argument to allow for do-block syntax ([#13338]).
* `cov` and `cor` don't use keyword arguments anymore and are therefore now type stable ([#13465]).
* Arrays and linear algebra:
* All dimensions indexed by scalars are now dropped, whereas previously only
trailing scalar dimensions would be omitted from the result ([#13612]). This
is a very major behavioral change, but should cause obvious failures. To retain
a dimension sliced with a scalar `i` slice with `i:i` instead.
* Dimensions indexed by multidimensional arrays add dimensions. More generally, the
dimensionality of the result is the sum of the dimensionalities of the indices ([#15431]).
* New `normalize` and `normalize!` convenience functions for normalizing
vectors ([#13681]).
* QR matrix factorization:
* New method for generic QR with column pivoting ([#13480]).
* New method for polar decompositions of `AbstractVector`s ([#13681]).
* A new `SparseVector` type allows for one-dimensional sparse arrays.
Slicing and reshaping sparse matrices now return vectors when
appropriate. The `sparsevec` function returns a one-dimensional sparse
vector instead of a one-column sparse matrix. ([#13440])
* Rank one update and downdate functions, `lowrankupdate`, `lowrankupdate!`, `lowrankdowndate`,
and `lowrankdowndate!`, for dense Cholesky factorizations ([#14243], [#14424])
* All `sparse` methods now retain provided numerical zeros as structural nonzeros; to
drop numerical zeros, use `dropzeros!` ([#14798], [#15242]).
* `setindex!` methods for sparse matrices and vectors no longer purge allocated entries
on zero assignment. To drop stored entries from sparse matrices and vectors, use
`Base.SparseArrays.dropstored!` ([#17404]).
* New `foreach` function for calling a function on every element of a collection when
the results are not needed ([#13774]). As compared to `map(f, v)`, which allocates and
returns a result array, `foreach(f, v)` calls `f` on each element of `v`, returning nothing.
* `Cmd(cmd; ...)` now accepts new Windows-specific options `windows_verbatim`
(to alter Windows command-line generation) and `windows_hide` (to
suppress creation of new console windows) ([#13780]).
* Statistics:
* Improve performance of `quantile` ([#14413]).
* `extrema` can now operate over a region ([#15550]).
* The new `Base.StackTraces` module makes stack traces easier to use programmatically ([#14469]).
* There is now a default no-op `flush(io)` function for all `IO` types ([#16403]).
* Concatenating dense and sparse matrices now returns a sparse matrix ([#15172]).
* The `libjulia` library is now properly versioned and installed to the public `<prefix>/lib`
directory, instead of the private `<prefix>/lib/julia` directory ([#16362]).
* System reflection is now more consistently exposed from Sys and not Base.
`OS_NAME` has been replaced by `Sys.KERNEL` and always reports the name of the
kernel (as reported by `uname`). The `@windows_only` and `@osx` family of macros
have been replaced with functions such as `is_windows()` and `is_apple()`.
There is now also a `@static` macro that will evaluate the condition of an
if-statement at compile time, for when a static branch is required ([#16219]).
* Prime number related functions have been moved from `Base` to the
[Primes.jl package](https://github.com/JuliaMath/Primes.jl) ([#16481]).
* `Date` and `DateTime` values can now be rounded to a specified resolution (e.g., 1 month or
15 minutes) with `floor`, `ceil`, and `round` ([#17037]).
* File handling:
* The `open` function now respects `umask` on UNIX when creating files ([#16466], [#16502]).
* A new function `walkdir()` returns an iterator that walks the directory tree of a directory. ([#1765])
```
for (root, dirs, files) in walkdir(expanduser("~/.julia/v0.5/Plots/src"))
println("$(length(files)) \t files in $root")
end
19 files in /Users/me/.julia/v0.5/Plots/src
15 files in /Users/me/.julia/v0.5/Plots/src/backends
4 files in /Users/me/.julia/v0.5/Plots/src/deprecated
```
* A new function `chown()` changes the ownership of files. ([#15007])
Deprecated or removed
---------------------
* The following function names have been simplified and unified ([#13232]):
* `get_bigfloat_precision` -> `precision(BigFloat)`
* `set_bigfloat_precision` -> `setprecision`
* `with_bigfloat_precision` -> `setprecision`
* `get_rounding` -> `rounding`
* `set_rounding` -> `setrounding`
* `with_rounding` -> `setrounding`
* The method `A_ldiv_B!(SparseMatrixCSC, StrideVecOrMat)` has been deprecated
in favor of versions that require the matrix to be in factored form
([#13496]).
* Deprecate `chol(A,Val{:U/:L})` in favor of `chol(A)` ([#13680]).
* `issym` is deprecated in favor of `issymmetric` to match similar functions
(`ishermitian`, ...) ([#15192])
* `scale` is deprecated in favor of either `α*A`, `Diagonal(x)*A`, or `A*Diagonal(x)`. ([#15258])
* `xdump` is removed, and `dump` now simply shows the full representation of a value.
`dump` should not be overloaded, since it is for examining concrete structure ([#4163]).
* `sub` and `slice` have been deprecated in favor of `view` ([#16972])
* The no-op `transpose` fallback has been deprecated. Consider introducing suitable
`transpose` methods or calling `permutedims(x, [2,1])` ([#13171], [#17075], [#17374]).
[PkgDev]: https://github.com/JuliaLang/PkgDev.jl
<!--- generated by NEWS-update.jl: -->
[#550]: https://github.com/JuliaLang/julia/issues/550
[#964]: https://github.com/JuliaLang/julia/issues/964
[#1090]: https://github.com/JuliaLang/julia/issues/1090
[#1765]: https://github.com/JuliaLang/julia/issues/1765
[#4163]: https://github.com/JuliaLang/julia/issues/4163
[#4211]: https://github.com/JuliaLang/julia/issues/4211
[#4470]: https://github.com/JuliaLang/julia/issues/4470
[#4867]: https://github.com/JuliaLang/julia/issues/4867
[#6190]: https://github.com/JuliaLang/julia/issues/6190
[#7258]: https://github.com/JuliaLang/julia/issues/7258
[#8036]: https://github.com/JuliaLang/julia/issues/8036
[#8846]: https://github.com/JuliaLang/julia/issues/8846
[#9503]: https://github.com/JuliaLang/julia/issues/9503
[#9627]: https://github.com/JuliaLang/julia/issues/9627
[#11196]: https://github.com/JuliaLang/julia/issues/11196
[#11242]: https://github.com/JuliaLang/julia/issues/11242
[#13062]: https://github.com/JuliaLang/julia/issues/13062
[#13171]: https://github.com/JuliaLang/julia/issues/13171
[#13232]: https://github.com/JuliaLang/julia/issues/13232
[#13338]: https://github.com/JuliaLang/julia/issues/13338
[#13387]: https://github.com/JuliaLang/julia/issues/13387
[#13412]: https://github.com/JuliaLang/julia/issues/13412
[#13440]: https://github.com/JuliaLang/julia/issues/13440
[#13465]: https://github.com/JuliaLang/julia/issues/13465
[#13480]: https://github.com/JuliaLang/julia/issues/13480
[#13496]: https://github.com/JuliaLang/julia/issues/13496
[#13542]: https://github.com/JuliaLang/julia/issues/13542
[#13612]: https://github.com/JuliaLang/julia/issues/13612
[#13680]: https://github.com/JuliaLang/julia/issues/13680
[#13681]: https://github.com/JuliaLang/julia/issues/13681
[#13774]: https://github.com/JuliaLang/julia/issues/13774
[#13780]: https://github.com/JuliaLang/julia/issues/13780
[#13824]: https://github.com/JuliaLang/julia/issues/13824
[#13897]: https://github.com/JuliaLang/julia/issues/13897
[#14114]: https://github.com/JuliaLang/julia/issues/14114
[#14194]: https://github.com/JuliaLang/julia/issues/14194
[#14243]: https://github.com/JuliaLang/julia/issues/14243
[#14413]: https://github.com/JuliaLang/julia/issues/14413
[#14424]: https://github.com/JuliaLang/julia/issues/14424
[#14469]: https://github.com/JuliaLang/julia/issues/14469
[#14519]: https://github.com/JuliaLang/julia/issues/14519
[#14759]: https://github.com/JuliaLang/julia/issues/14759
[#14798]: https://github.com/JuliaLang/julia/issues/14798
[#15007]: https://github.com/JuliaLang/julia/issues/15007
[#15032]: https://github.com/JuliaLang/julia/issues/15032
[#15172]: https://github.com/JuliaLang/julia/issues/15172
[#15192]: https://github.com/JuliaLang/julia/issues/15192
[#15242]: https://github.com/JuliaLang/julia/issues/15242
[#15244]: https://github.com/JuliaLang/julia/issues/15244
[#15258]: https://github.com/JuliaLang/julia/issues/15258
[#15409]: https://github.com/JuliaLang/julia/issues/15409
[#15431]: https://github.com/JuliaLang/julia/issues/15431
[#15524]: https://github.com/JuliaLang/julia/issues/15524
[#15550]: https://github.com/JuliaLang/julia/issues/15550
[#15609]: https://github.com/JuliaLang/julia/issues/15609
[#15731]: https://github.com/JuliaLang/julia/issues/15731
[#15763]: https://github.com/JuliaLang/julia/issues/15763
[#15975]: https://github.com/JuliaLang/julia/issues/15975
[#16024]: https://github.com/JuliaLang/julia/issues/16024
[#16058]: https://github.com/JuliaLang/julia/issues/16058
[#16071]: https://github.com/JuliaLang/julia/issues/16071
[#16107]: https://github.com/JuliaLang/julia/issues/16107
[#16219]: https://github.com/JuliaLang/julia/issues/16219
[#16260]: https://github.com/JuliaLang/julia/issues/16260
[#16285]: https://github.com/JuliaLang/julia/issues/16285
[#16362]: https://github.com/JuliaLang/julia/issues/16362
[#16403]: https://github.com/JuliaLang/julia/issues/16403
[#16404]: https://github.com/JuliaLang/julia/issues/16404
[#16455]: https://github.com/JuliaLang/julia/issues/16455
[#16466]: https://github.com/JuliaLang/julia/issues/16466
[#16481]: https://github.com/JuliaLang/julia/issues/16481
[#16502]: https://github.com/JuliaLang/julia/issues/16502
[#16621]: https://github.com/JuliaLang/julia/issues/16621
[#16622]: https://github.com/JuliaLang/julia/issues/16622
[#16645]: https://github.com/JuliaLang/julia/issues/16645
[#16663]: https://github.com/JuliaLang/julia/issues/16663
[#16731]: https://github.com/JuliaLang/julia/issues/16731
[#16972]: https://github.com/JuliaLang/julia/issues/16972
[#17037]: https://github.com/JuliaLang/julia/issues/17037
[#17075]: https://github.com/JuliaLang/julia/issues/17075
[#17132]: https://github.com/JuliaLang/julia/issues/17132
[#17266]: https://github.com/JuliaLang/julia/issues/17266
[#17300]: https://github.com/JuliaLang/julia/issues/17300
[#17323]: https://github.com/JuliaLang/julia/issues/17323
[#17374]: https://github.com/JuliaLang/julia/issues/17374
[#17393]: https://github.com/JuliaLang/julia/issues/17393
[#17402]: https://github.com/JuliaLang/julia/issues/17402
[#17404]: https://github.com/JuliaLang/julia/issues/17404
[#17510]: https://github.com/JuliaLang/julia/issues/17510
[#17546]: https://github.com/JuliaLang/julia/issues/17546
