Release Notes J9.6

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Work on J9.6 started in November 2023. J9.6.0-beta1 was released 20240102.

Request for Comments

Proposed addition of .. for comment delimiter and ... for line continuation

• The J word .., when not further inflected, is equivalent to NB., starting a comment that ends at the next end-of-line (LF).
• The J word ..., when not further inflected, is equivalent to NB., starting a comment that ends at the next end-of-line (LF), and the following line is appended as J words in place of the ....

Example:

  vec =. i. #y  .. index vector of length #y
  adj =. +/   ... add the weighted values
         vec * y   ..  weight each element of y by its position

Comment on the proposal

Changes to the J engine

• List of problems fixed from J9.5

Summary of Changes to the J Language in the release

• New datatype floating16 for double-double floating-point values
• New datatypes integer2 and integer4 for 2-byte and 4-byte integer values
• New primitive verb x c. y converts noun y to the type given by x. x is the desired type/precision, and is the value 3!:0 (aka datatype) will return if applied to the result of c.
• New foreign 9!:33 y controls number of retries for elliptic-curve factoring
• New locative form: name__nn, where nn is a negative integer, looks up name starting in the namespace shown in the debug stack (dbstk''). nn of _1 refers to the topmost frame (the newest suspended frame), _2 to its caller, etc.
• Enhanced foreign x 5!:5 y gives only the selected valence of explicit definitions
• I.^:_1 y defined to return a list of the frequencies of the atoms of y
• 18!:4 removed except as documentation. The cover functions cocurrent and coclass perform the same function they always did, but the underlying 18!:4 itself, which had a quirky definition, can no longer be used directly.
• New foreign 18!:6 y recalculates the Bloom filter for locale y.
• By default, all named locales are marked permanent when created. An option on 18!:3 y allows for creating an impermanent named locale.
• coerase (18!:55) has no effect on permanent locales. To get the same effect, you must manually delete all names from the locale and reset its Bloom filter.
• New modifier train NVC added
• x ($,)!.fill y supported

J9.6.0-beta15 (unreleased)

• x |.!.n y runs inplace when possible
• x ($,)!.fill y supported

J9.6.0-beta14 (the current beta)

• Add new modifier train NVC
• Assignments ended by ) allow inplacing. Ex: (nm =: nm , 'a') , 'b'
• ([x] 128!:10 y) (LUP decomposition) finds a suitable P

J9.6.0-beta13

• Fix mismatch between private locale and implied locale

J9.6.0-beta12

• Fix for crash in postmortem debugging

J9.6.0-beta11

• Direct definitions (created using {{ }}) are displayed on the console with {{ }}. In other linear representations they continue to use m : 0.

J9.6.0-beta10

• New foreign 18!:6 y recalculates the Bloom filter for locale y.
• By default, all named locales are marked permanent when created. An option on 18!:3 y allows for creating an impermanent named locale.
• coerase (18!:55) has no effect on permanent locales. To get the same effect, you must manually delete all names from the locale and reset its Bloom filter. Supporting the very rare case of deleting a named locale is not worth the burden it imposes on a multithreaded system.

J9.6.0-beta9

• 18!:4 removed except as documentation. The cover functions cocurrent and coclass perform the same function they always did, but the underlying 18!:4 itself, which had a quirky definition, can no longer be used directly.
• Execution of named functions rewritten, simpler & faster
• If you delete the implied locale, the implied locale is set to z (previously you were left with no implied locale and no path)

J9.6.0-beta8

• Warning message given if 18!:4 is used. 18!:4 will be removed from beta9.
• Improvements to the debugger and its interaction with Jqt and JHS, contributed by Marcin Żołek

J9.6.0-beta7

• Beta users should install this beta before installing later betas. This will update libraries that are used in later betas

J9.6.0-beta6 withdrawn

J9.6.0-beta5

• I.^:_1 y defined to return a list of the frequencies of the atoms of y
• execution of explicit definitions rewritten: faster, leaner

J9.6.0-beta4

• 55 T. threadpool# deletes a thread from the specified threadpool
• Undefined sentences, such as NB watch out, display the 'noun result was required' message. This can be controlled using 9!:55
• Anonymous explicit definitions are now given a place in the debug stack. Example: myverb =: {{ x + y }}"0
• 13!:13 (dbstk) includes only the active valence of the text of the executing entity

J9.6.0-beta3

• Compensated summation now gives infinite result rather than NaN error where possible
• m!:n (that is, the function that creates the derived verb) rewritten, a little faster and less memory
• Enhanced foreign x 5!:5 y gives only the selected valence of explicit definitions

J9.6.0-beta2

• The special forms ((q i.]) { p"_) y and (q&i. { p"_) y are no longer recognized. They are superseded by (p {~ q i. ]) y
• (p {~ q i. ]) y runs inplace if possible
• Virtual arguments to a task are realized in the task rather than in the caller, where possible
• x , y faster and better when one argument is empty
• fixed-precision datatypes given higher conversion priority than J native numbers
• 256-bit code for +/ y and +/@:*"1 y when y is floating16
• Fast support for +/ y, +/\ y, and +/\. y when y is integer2 or integer4
• q: y on extended integer y now tries multiple random elliptic curves instead of just one. The default number is 3 but can be changed by 9!:33 y
• New locative form: name__nn, where nn is a negative integer, looks up name starting in the namespace shown in the debug stack (dbstk''). nn of _1 refers to the topmost frame (the newest suspended frame), _2 to its caller, etc.
• New feature: postmortem debugging allows you to inspect the situation after a sentence failed while debugging wasn't turned on.
• screen display of a tacit verb uses default formatting instead of maximum precision

J9.6.0-beta1

• New datatype floating16 for double-double floating-point values
• New datatypes integer2 and integer4 for 2-byte and 4-byte integer values
• New primitive verb x c. y converts noun y to the type given by x. x is the desired type/precision, and is the value 3!:0 (aka datatype) will return if applied to the result of c.

Changes to the Qt IDE

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