Julia v1.12 Release Notes

New language features

Language changes

When methods are replaced with exactly equivalent ones, the old method is no longer deleted implicitly simultaneously, although the new method does take priority and become more specific than the old method. Thus if the new method is deleted later, the old method will resume operating. This can be useful to mocking frameworks (such as in SparseArrays, Pluto, and Mocking, among others), as they do not need to explicitly restore the old method. While inference and compilation still must be repeated with this, it also may pave the way for inference to be able to intelligently re-use the old results, once the new method is deleted. ([#53415])
Macro expansion will no longer eargerly recurse into into Expr(:toplevel) expressions returned from macros. Instead, macro expansion of :toplevel expressions will be delayed until evaluation time. This allows a later expression within a given :toplevel expression to make use of macros defined earlier in the same :toplevel expression. ([#53515])

Compiler/Runtime improvements

Generated LLVM IR now uses actual pointer types instead of passing pointers as integers. This affects llvmcall: Inline LLVM IR should be updated to use i8* or ptr instead of i32 or i64, and remove unneeded ptrtoint/inttoptr conversions. For compatibility, IR with integer pointers is still supported, but generates a deprecation warning. ([#53687])

Command-line option changes

The -m/--module flag can be passed to run the main function inside a package with a set of arguments. This main function should be declared using @main to indicate that it is an entry point.

Multi-threading changes

Build system changes

New library functions

logrange(start, stop; length) makes a range of constant ratio, instead of constant step ([#39071])
The new isfull(c::Channel) function can be used to check if put!(c, some_value) will block. ([#53159])
waitany(tasks; throw=false) and waitall(tasks; failfast=false, throw=false) which wait multiple tasks at once ([#53341]).

New library features

invmod(n, T) where T is a native integer type now computes the modular inverse of n in the modular integer ring that T defines ([#52180]).
invmod(n) is an abbreviation for invmod(n, typeof(n)) for native integer types ([#52180]).
replace(string, pattern...) now supports an optional IO argument to write the output to a stream rather than returning a string ([#48625]).
sizehint!(s, n) now supports an optional shrink argument to disable shrinking ([#51929]).
New function Docs.hasdoc(module, symbol) tells whether a name has a docstring ([#52139]).
New function Docs.undocumented_names(module) returns a module's undocumented public names ([#52413]).
Passing an IOBuffer as a stdout argument for Process spawn now works as expected, synchronized with wait or success, so a Base.BufferStream is no longer required there for correctness to avoid data races ([#52461]).
After a process exits, closewrite will no longer be automatically called on the stream passed to it. Call wait on the process instead to ensure the content is fully written, then call closewrite manually to avoid data-races. Or use the callback form of open to have all that handled automatically.
@timed now additionally returns the elapsed compilation and recompilation time ([#52889])
filter can now act on a NamedTuple ([#50795]).
tempname can now take a suffix string to allow the file name to include a suffix and include that suffix in the uniquing checking ([#53474])
RegexMatch objects can now be used to construct NamedTuples and Dicts ([#50988])

Standard library changes

gcdx(0, 0) now returns (0, 0, 0) instead of (0, 1, 0) ([#40989]).

StyledStrings

JuliaSyntaxHighlighting

Package Manager

LinearAlgebra

rank can now take a QRPivoted matrix to allow rank estimation via QR factorization ([#54283]).

Logging

Printf

Profile

Random

REPL

SuiteSparse

SparseArrays

Test

Dates

Statistics

Distributed

Unicode

DelimitedFiles

InteractiveUtils

Deprecated or removed

External dependencies

Tooling Improvements