System/ReleaseNotes/J903

J903 beta development started in Dec 2020, and 903-beta-a was released 21 Dec 2020.

Changes to the J engine

• List of problems fixed from J9.02

Summary of Changes to the J Language in the release

• New foreigns 9!:4 and 9!:5 support Nameref Caching, a way of avoiding name-lookup overhead especially useful when you have many locatives or long search paths.
• New foreign u 4!:8 (adverb) produces a cached reference to u
• Old foreigns 2!:2 and 2!:3 are removed from the language
• +/!.0 y performs compensated summation (addition with improved accuracy)
• x +/@:*"1!.0 y performs the computation at twice the precision of floats
• x i.!.1 y assumes that x and y are both in nondescending order; faster when cells are integer lists. Supports IRS.
• name_: is a self-effacing reference to name. name is deleted, and the reference is replaced by its value, made inplaceable if possible.
• The tacit-modifier language from early versions of J has been reinstated.
• New foreigns 9!:54 and 9!:55 will cause the interpreter to type a warning message when certain inefficient usages are detected

unreleased work in progress

• New foreigns 9!:54 and 9!:55 will cause the interpreter to type a warning message when certain inefficient usages are detected

J903 beta-s (the current beta)

• added modifier train (C0 C1)

J903 beta-r

• implementation change: maximum rank of nouns and verbs is now 63
• change from the previous beta: self-effacing reference is signaled by name_: rather than name::
• language change: the tacit-modifier language from early versions of J has been reinstated. Old J books are once again valid.
• 128!:10 upgraded to support rational arithmetic and non-AVX

J903 beta-q

• virtual blocks allowed in boxes in more situations, see details about virtual blocks
• 256-bit instructions used for 1-byte frets in ([x] f;.12 y) (AVX2 only)
• +/ y, >./ y, <./ y now use 32 accumulators on float arguments rather than 16 (AVX2 only)
• 128!:10 y calculates LU decomposition of y

J903 beta-p withdrawn

J903 beta-o

• new feature: name:: is a self-effacing reference to name. name is deleted, and the reference is replaced by its value, made inplaceable if possible.
• Parser revisited in detail, much faster (by 2x or more for sentences containing only singletons)
• code for atomic singletons rewritten, lower overhead and with faster NaN-checking for floats
• (x # y) rewritten to use 256-instructions on x, and faster copy for atomic y
• lowest-level memory-allocation paths rewritten to reduce register spills
• (AVX2 only) (x {"1 y) improved for integer and float y
• (x ((> |) * ]) y (force near-0 IEEE values to 0) supported with special code when x is a float atom and y is float (AVX2 only)

J903 beta-n withdrawn

J903 beta-l

• Inner loop of transpose (|:) unrolled, 50% faster
• (+/ y) (+/\ y) (+/\. y) (and also for - and *) rewritten for integer y, faster
• Complete rewrite of combinations created by hook/fork/@:/&:/&./&.: . Now blocks are freed immediately after the verb they are applied to, provided that verb did not save the value or modify it inplace. Also, in hooks (f g h), the cases where f or h are [ ] @[ @] are handled specially to remove overhead.

J903 beta-k

• 256-bit instructions used for (I. y) when y is boolean (AVX and AVX2 only)
• 256-bit instructions used for (+/ y) when y is a boolean list (AVX and AVX2 only)
• 256-bit instructions used for x | y on integers, when x is a power of 2 (64-bit only)
• (AVX2 only) +/\ y, <./\ y, and >./\ y on float lists improved

J903 beta-j

• bitwise booleans x m b. y implemented with 256-bit instructions (AVX and AVX2 only)
• comparison combinations on bytes performed with word-wide comparisons
• comparison combinations i.&0@:comp (also i:, also 1, also +/) use 256-bit instructions (AVX and AVX2 only)
• sequential-search loops recoded (list i. atom) for AVX and AVX2, faster
• special code for (i. <./) y etc. no longer faster, deleted
• internal coding of types changed. There should be no visible effects, but if there are any they will be in sparse arrays
• +/!.0 y hand-unrolled, 2x faster
• x E. y on characters recoded, faster when matches are frequent (AVX and AVX2 only)

J903 beta-i

• (64-bit only) x ([ -. -.) y is implemented as a member of the i.-family, performing only one hash
• (AVX2 only) all loops for arithmetic primitives with heterogeneous arguments recoded, faster
• (> y) rewritten to avoid needless copying of fill
• (AVX2 only) all loops for arithmetic primitives rewritten with better addressing modes, faster
• (64-bit only) special code for -.&n reinstated, applying also to ([ -. -.)&n
• Precomputed searches (m&i., (e.&n, (i.&1@:>&n, etc) support comparison tolerance

J903 beta-h

• (AVX2 only) +/\ y, <./\ y, and >./\ y on float lists rewritten
• (AVX2 only) all loops for arithmetic primitives with homogeneous arguments recoded, much faster on inplace arguments
• (AVX2 only) internal memory-copying routine rewritten, faster for all sizes, but especially for non-multiples of 32 bytes

J903 beta-g

• search for private names faster
• debut of PPPP: pre-parsed parenthesized primitives. Parenthesized expressions that contain only primitives and do not cause executions of a verb (thus (+/ % #) but not (i. 1e8)) are parsed when an explicit entity is defined, avoiding the overhead of parsing each time the sentence is executed
• arithmetic dyads + - % * >. <. coded to use 256-bit instructions when one argument is float and the other is integer (AVX2 only)
• +./\ y, *./\ y, =/\ y, ~:/\ y recoded for boolean arrays of rank >1
• All atomic suffix scans f/\. y recoded for boolean arrays of rank >1
• =/\ y and ~:/\ y recoded for boolean list arguments

J903 beta-f

• fix blunder in assert.: sentence no longer executed if 0=9!:34''
• cached namerefs expose some of the value's characteristics to combining modifiers: IRS and immediate-opening
• x i.!.1 y assumes that x and y are both in nondescending order; faster when cells are integer lists. Supports IRS.
• Name lookups using the search path recoded, reducing the number of searches; Bloom filter added to public locales to allow fast skipping of locales with few names

J903 beta-e

• +/ y, <./ y , and >./ y for floating-point y with rank >1 rewritten to use less cache bandwidth, >2x faster
• +/!.0 y performs compensated summation (addition with improved accuracy)
• x +/@:*"1!.0 y performs the computation at twice the precision of floats

J903 beta-d

• x ]\ y, x [\ y, and x ,\ y return a virtual result when x<0 and there is no shard
• f/ y faster on boolean arrays of rank >1 when f is a primitive logical operation
• +/ y rewritten for boolean y, faster
• special code for x f/@:g y with atomic f & g rewritten. Most special cases removed, as they are no longer faster than the normal code. Special code is used only when g cannot be executed in place.
• New foreigns 9!:4 and 9!:5 support nameref caching, a way of avoiding name-lookup overhead especially useful when you have many locatives or long search paths. Put ". :: 1:'9!:5(1)' at the top of your script to see if you can use the feature.
• New foreign u 4!:8 (adverb) produces a cached reference to u
• Old foreigns 2!:2 and 2!:3 are removed from the language
• |. y executes in place where possible
• u"n is identical to u when n equals the ranks of u. If you need to generate a compound, use u"v.
• in for_xyz. loops, a virtual block is used for xyz, and xyz_index cannot be modified inside the loop
• Code for atomic/"1 y when 1-cells of y have length 2 rewritten

J903 beta-c withdrawn

J903 beta-b withdrawn

J903 beta-a

Changes to the Qt IDE

Changes since 1.8.5 (J901), good for Qt IDE 1.9.4 (J903) and later:

wd commands:

• allow -1 (ignored) in maxwh command
• add spacing style to grid layout (horizontal/vertical spacing between grid elements)
• add nostretchlast style to table (prevents last column stretching to fill space available)
• add MaxVisibleItems configuration, used by combobox
• add uppercase style to edit box
• add flush and margins styles to groupbox
• add wd command qhwndx
• add socket event

others:

• add Ctrl+Shift+Q to close all textviews
• do not trim sentences sent to JE
• ensure sentences sent to JE do not include line separators
• ensure textview saves position in a session
• support syntax highlight printing
• support syntax highlighting for {{...}} definitions
• build for mac and windows uses Qt 5.15