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Julia v1.7 Release Notes

New language features

  • (; a, b) = x can now be used to destructure properties a and b of x. This syntax is equivalent to a = getproperty(x, :a) and similarly for b. ([#39285])
  • Implicit multiplication by juxtaposition is now allowed for radical symbols (e.g., x√y and x∛y). ([#40173])
  • The short-circuiting operators && and || can now be dotted to participate in broadcast fusion as .&& and .||. ([#39594])
  • ⫪ (U+2AEA, \Top, \downvDash) and ⫫ (U+2AEB, \Bot, \upvDash, \indep) may now be used as binary operators with comparison precedence. ([#39403])
  • Repeated semicolons may now be used inside array literals to separate dimensions of an array, with the number of semicolons specifying the particular dimension. Just as the single semicolon in [A; B] has always described concatenating along the first dimension (vertically), now two semicolons [A;; B] do so in the second dimension (horizontally), three semicolons ;;; in the third, and so on. ([#33697])

Language changes

  • macroexpand, @macroexpand, and @macroexpand1 no longer wrap errors in a LoadError. To reduce breakage, @test_throws has been modified so that many affected tests will still pass ([#38379]].
  • The middle dot · (\cdotp U+00b7) and the Greek interpunct · (U+0387) are now treated as equivalent to the dot operator ⋅ (\cdot U+22c5) (#25157).
  • The minus sign − (\minus U+2212) is now treated as equivalent to the hyphen-minus sign - (U+002d).
  • Destructuring will no longer mutate values on the left hand side while iterating through values on the right hand side. In the example of an array x, x[2], x[1] = x will now swap the first and second entry of x, whereas it used to fill both entries with x[1] because x[2] was mutated during the iteration of x. ([#40737])
  • The default random number generator has changed, so all random numbers will be different (even with the same seed) unless an explicit RNG object is used. See the section on the Random standard library below.

Compiler/Runtime improvements

Command-line option changes

  • The Julia --project option and the JULIA_PROJECT environment variable now support selecting shared environments like .julia/environments/myenv the same way the package management console does: use julia --project=@myenv resp. export JULIA_PROJECT="@myenv" ([#40025]).

Multi-threading changes

  • Intrinsics for atomic pointer operations are now defined for certain byte sizes. ([#37847])
  • Support for declaring and using individual fields of a mutable struct as atomic now available. ([#37847])
  • If the JULIA_NUM_THREADS environment variable is set to auto, then the number of threads will be set to the number of CPU threads ([#38952])
  • Every Task object has a local random number generator state, providing reproducible (schedule-independent) execution of parallel simulation code by default. The default generator is also significantly faster in parallel than in previous versions.

Build system changes

New library functions

  • Two argument methods findmax(f, domain), argmax(f, domain) and the corresponding min versions ([#27613]).
  • isunordered(x) returns true if x is value that is normally unordered, such as NaN or missing.
  • New keepat!(vector, inds) function which is the inplace equivalent of vector[inds] for a list inds of integers ([#36229]).
  • New macro Base.@invokelatest f(args...; kwargs...) provides a convenient way to call Base.invokelatest(f, args...; kwargs...) ([#37971])
  • Two arguments method lock(f, lck) now accepts a Channel as the second argument. ([#39312])
  • New functor Returns(value), which returns value for any arguments ([#39794])
  • New macro Base.@invoke f(arg1::T1, arg2::T2; kwargs...) provides an easier syntax to call invoke(f, Tuple{T1,T2}, arg1, arg2; kwargs...) ([#38438])
  • New macros @something and @coalesce which are short-circuiting versions of something and coalesce, respectively ([#40729])
  • New function redirect_stdio for redirecting stdin, stdout and stderr ([#37978]).

New library features

  • The optional keyword argument context of sprint can now be set to a tuple of :key => value pairs to specify multiple attributes. ([#39381])
  • bytes2hex and hex2bytes are no longer limited to arguments of type Union{String,AbstractVector{UInt8}} and now only require that they're iterable and have a length. ([#39710])

Standard library changes

  • Long strings are now elided using the syntax "head" ⋯ 12345 bytes ⋯ "tail" when displayed in the REPL ([#40736]).
  • count and findall now accept an AbstractChar argument to search for a character in a string ([#38675]).
  • range now supports the range(start, stop) and range(start, stop, length) methods ([#39228]).
  • range now supports start as an optional keyword argument ([#38041]).
  • Some operations on ranges will return a StepRangeLen instead of a StepRange, to allow the resulting step to be zero. Previously, λ .* (1:9) gave an error when λ = 0. ([#40320])
  • islowercase and isuppercase are now compliant with the Unicode lower/uppercase categories ([#38574]).
  • iseven and isodd functions now support non-Integer numeric types ([#38976]).
  • escape_string can now receive a collection of characters in the keyword keep that are to be kept as they are. ([#38597]).
  • getindex can now be used on NamedTuples with multiple values ([#38878])
  • Subtypes of AbstractRange now correctly follow the general array indexing behavior when indexed by Bools, erroring for scalar Bools and treating arrays (including ranges) of Bool as an logical index ([#31829])
  • keys(::RegexMatch) is now defined to return the capture's keys, by name if named, or by index if not ([#37299]).
  • keys(::Generator) is now defined to return the iterator's keys ([#34678])
  • RegexMatch now iterate to give their captures. ([#34355]).
  • Test.@test now accepts broken and skip boolean keyword arguments, which mimic Test.@test_broken and Test.@test_skip behavior, but allows skipping tests failing only under certain conditions. For example 
    if T == Float64
    @test_broken isequal(complex(one(T)) / complex(T(Inf), T(-Inf)), complex(zero(T), zero(T)))
else
    @test isequal(complex(one(T)) / complex(T(Inf), T(-Inf)), complex(zero(T), zero(T)))
end
    can be replaced by 
    @test isequal(complex(one(T)) / complex(T(Inf), T(-Inf)), complex(zero(T), zero(T))) broken=(T == Float64)
    ([#39322])
  • @lock is now exported from Base ([#39588]).
  • The experimental function Base.catch_stack() has been renamed to current_exceptions(), exported from Base and given a more specific return type ([#29901])
  • Some degree trigonometric functions, sind, cosd, tand, asind, acosd, asecd, acscd, acotd, atand now accept an square matrix ([#39758]).

Package Manager

LinearAlgebra

  • Use Libblastrampoline to pick a BLAS and LAPACK at runtime. By default it forwards to OpenBLAS in the Julia distribution. The forwarding mechanism can be used by packages to replace the BLAS and LAPACK with user preferences. ([#39455])
  • On aarch64, OpenBLAS now uses an ILP64 BLAS like all other 64-bit platforms. ([#39436])
  • OpenBLAS is updated to 0.3.13. ([#39216])
  • SuiteSparse is updated to 5.8.1. ([#39455])
  • The shape of an UpperHessenberg matrix is preserved under certain arithmetic operations, e.g. when multiplying or dividing by an UpperTriangular matrix. ([#40039])
  • Real quasitriangular Schur factorizations S can now be efficiently converted to complex upper-triangular form with Schur{Complex}(S) ([#40573]).
  • cis(A) now supports matrix arguments ([#40194]).
  • dot now supports UniformScaling with AbstractMatrix ([#40250]).
  • qr[!] and lu[!] now support LinearAlgebra.PivotingStrategy (singleton type) values as their optional pivot argument: defaults are qr(A, NoPivot()) (vs. qr(A, ColumnNorm()) for pivoting) and lu(A, RowMaximum()) (vs. lu(A, NoPivot()) without pivoting); the former Val{true/false}-based calls are deprecated. ([#40623])
  • det(M::AbstractMatrix{BigInt}) now calls det_bareiss(M), which uses the Bareiss algorithm to calculate precise values.([#40868]).

Markdown

Printf

Random

  • The default random number generator has been changed from Mersenne Twister to Xoshiro256++. The new generator has smaller state, better performance, and superior statistical properties. This generator is the one used for reproducible Task-local randomness.

REPL

SparseArrays

  • new sizehint!(::SparseMatrixCSC, ::Integer) method ([#30676]).
  • cholesky() now fully preserves the user-specified permutation. ([#40560])
  • issparse now applies consistently to all wrapper arrays, including nested, by checking issparse on the wrapped parent array ([#37644]).

Dates

  • The Dates.periods function can be used to get the Vector of Periods that comprise a CompoundPeriod ([#39169]).

Statistics

Sockets

Distributed

UUIDs

Mmap

  • mmap is now exported ([#39816]).

DelimitedFiles

  • readdlm now defaults to use_mmap=false on all OSes for consistent reliability in abnormal filesystem situations ([#40415]).

Deprecated or removed

  • Multiple successive semicolons in an array expresion were previously ignored (e.g., [1 ;; 2] == [1 ; 2]). This is now being used to separate dimensions for array literals. (see New language features)

External dependencies

Tooling Improvements