Release Notes J9.5
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Work on J9.5 started in March 2023. J9.5.0-beta1 was released 20230423.
Changes to the J engine
Summary of Changes to the J Language in the release
- new primitive: u m. n performs the operation u(mod n), i. e. using modular arithmetic. n and any arguments to the derived verb must be tolerantly integral or extended integer; results will be integer or extended integer; u must be one of + - * % ^ %. (-/ . *). The derived verb has only dyadic valence except for (% m. n) and (%. m. n) which are bivalent.
- domain of x ;: y expanded: new actions added.
- New foreign: ([x] 15!:18 y) creates a block with value y but with the data area aligned to a cacheline boundary
- Language extension: (x { y) where x is a boxed numeric array now allows >x to have any rank. Each 1-cell of >x is the index list of a cell of y
- Incompatible language restriction: In (x m} y), m must be an atom.
For compatibility with previous versions of J, the deprecated forms (<"0 numeric-array)} and (<"1 numeric-array)} are still supported (see below)
unreleased work in progress
- none yet
J9.5.0-beta7 (the current beta)
- fix bug introduced in beta-4
J9.5.0-beta6
- (<<<x) { y rewritten again, faster and less memory
- x m} y fast paths added when m selects a single cell and y is a direct type
J9.5.0-beta5
- New foreign: ([x] 15!:18 y) creates a block with value y but with the data area aligned to a cacheline boundary
- Language extension: (x { y) where x is a boxed numeric array now allows >x to have any rank. Each 1-cell of >x is the index list of a cell of y
- Incompatible language restriction: In (x m} y), m must be an atom.
For compatibility with previous versions of J, the deprecated forms (<"0 numeric-array)} and (<"1 numeric-array)} are still supported (see below)
Discussion: (x m} y) where m contained multiple boxes was slow, sometimes very slow. Moreover the boxes in m were required to select regions of the same shape, making the apparent generality of boxed m illusory. Restricting boxed m makes all the forms faster.
The supported multibox forms are deprecated and may be removed in a future version. You can update your code to use an atomic box as follows:
- x (<"0 numeric-array)} y should be replaced with x (<<numeric-array)} y
- x (<"1 numeric-array)} y should be replaced with x (<numeric-array)} y (or x numeric-array} y if you know that numeric-array has rank > 1)
If you have other multibox forms and need help rewriting them, send a message to the beta forum.
To see a warning when a deprecated form is executed, use 9!:55.
J9.5.0-beta4
- x { y recoded. Multidimensional indexing is faster, much faster for rank>2; virtual blocks are used more often; x overwritten in place where possible; complementary indexes faster and less space
- x m} y now supports doubly-boxed selectors with an efficient path
- q: y recoded for 64-bit, faster
J9.5.0-beta3
- #@> y supported by special code
- improvements to inverses containing constant functions
J9.5.0-beta2
- x m} y now has Integrated Rank Support. x m}"n y, formerly deprecated, is now recommended.
- domain of x ;: y expanded: new actions added. This code was contributed by Danil Osipchuk.
- 0 % m. n 0 is 0
- -/ . * m. n calculates modular determinant. This code was contributed by Cliff Reiter.
- complementary indexing (triple-boxed selectors) faster
J9.5.0-beta1
- 0!:n (used by the load and script verbs) discards the first line of a file if the first two characters in the line are #!
- x integer_atom&|@^ y recoded, about 2x faster
- special code for (x -@{`[`]} y (also with @:), which changes the sign of the addressed cells of y, when y is floating-point. Supports inplacing.
- new primitive: u m. n performs the operation u(mod n), i. e. using modular arithmetic. n and any arguments to the derived verb must be tolerantly integral or extended integer; results will be integer or extended integer; u must be one of + - * % ^ %.. The derived verb has only dyadic valence except for (% m. n) and (%. m. n) which are bivalent.
The code for %. m. n was contributed by Cliff Reiter.
Changes to the base system
Changes to the Qt IDE
- since beta5, Jqt on windows now uses Qt 6.5.2