# Ann: SWI-Prolog 8.3.29 **URL:** \ **Category:** Releases\ **Created:** [September 1, 2021, 3:45pm UTC](https://swi-prolog.discourse.group/t/ann-swi-prolog-8-3-29/4367 "2021-09-01T15:45:15Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![jan](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/jan/32/4_2.png) [@jan](https://swi-prolog.discourse.group/u/jan)\ **Post date:** [September 1, 2021, 3:45pm UTC](https://swi-prolog.discourse.group/t/ann-swi-prolog-8-3-29/4367/1 "2021-09-01T15:45:15Z")
Dear SWI-Prolog user, SWI-Prolog 8.3.29 is ready for download. This should be considered a pre-release of 8.4.0. If you are on the stable branch, please test your software with this version such that possible unnecessary regression on the stable series can be avoided. Higlights: - Eric Zinda’s new network based interface to other languages has been renamed to `mqi` (_Machine Query Interface_) to avoid confusion with LSP (Language Server Protocol). This also renamed the git submodule, so to update a git tree do: - By default, the toplevel now writes variable as \_A, \_B or just \_ if the variable appears only once. Setting the flag `toplevel_name_variables` to `false` disables this behaviour. Especially the anonymous variables simplify interpreting answers a lot 🙂 - Added trap/1 and gtrap/1 to trap the commandline (or graphical) debugger on an error exception whose formal part unifies with the given argument. Note that this traps the debugger, even if the exception is caught. - Various bug fixes for monotonic tabling, clause/2, format\_time/3, etc. See below. - Avoid possibility of hanging in multi-threaded applications when compiling with some GCC versions (over aggressive optimization). - Ubuntu PPAs are now build using PGO optimization. Also added Hirsute (Ubuntu 21.04). - The troublesome library(uuid) now provides a pure Prolog replacement if the dependency on ossp-uuid cannot be found. In this case uuid/1 produces a random UUID. - Make CHR work again in SWISH (or, more generally, in temporary modules). # SWI-Prolog Changelog since version 8.3.28 - BUILD: Use PGO optimization for the Debian builds. - FIXED: clause/2 (and related predicates) on clauses where unifications are moved into the head failed in a saved state. - FIXED: clause/2 for unification that was migrated to the head and used nested in a term used as argument to some body call (using B\_ARGVAR instead of B\_VAR). - ADDED: format\_time/3: handle `'%P'` on systems not using glibc. - FIXED: Adding missing newlines in tracer commands - TEST: Fixed answer tests for new toplevel output. - ADDED: Prolog flag `toplevel_name_variables`, which causes variables in toplevel answers to be named \_A, \_B, etc. Singleton variables are printed as \_. - ADDED: current\_temporary\_module/1 to library(modules). - FIXED: Avoid optimizing memory load, causing an infinite loop when creating a new atom. - FIXED: =../2 to avoid truncating to `int` (for arity \> 2g). - ADDED: trap/1, notrap/1 as commandline utilities to trap exceptions. - CLEANUP: Move the command line debug utils such as spy/1 from the boot files into a new library(prolog\_debug). - FIXED: make sure the monotonic propagation flag is only set during monotonic propagation and not while reevaluating non-monotonic nodes. - FIXED: Possibly loop adding a lazy monotonic dependency. - FIXED: date\_time\_stamp/2 was broken in timezone handling after e68098ba2b38d7d9597def1b4fc0a8cef1ed43cb. - FIXED: Possibly crash in completion detecting for lazy monotonic tabling. - FIXED: format\_time/3 using date/9 term computed the weekday and year day of the UTC time rather than the local time. Mike Elston. - TEST: one more test for lazy monotonic tabling. - FIXED: We must remove the queued answers or a recursive call will keep re-evaluating them. This triggered `tabling_monotonic_lazy_14` after fixing the issues from `tabling_monotonic_lazy_16`. The disadvantage is that if we get an exception during the propagation we cannot retry. There are probably more troubles with that and we should probably just abolish the involved tables. - FIXED: If we call an invalid table we must re-evaluate the table immediately, also if this is a lazy table and we are inside lazy answer propagation. - ENHANCED: Avoid recording duplicate dependencies for lazy monotonic tabling. - ENHANCED: trace/1,2: add recursion depth to output to make it easier to understand. - FIXED: Inconsistent behavior of current\_prolog\_flag/2 and prolog\_flag/2 in SICStus emulation. With SICStus emulation active, current\_prolog\_flag/2 and prolog\_flag/2 now always give the same results, and always take priority over the autoloadable prolog\_flag/2 from library(quintus). - FIXED: write\_term/2,3 numbervars for ‘$VAR’(N) terms where N is a GMP integer. - PPA: Groovy is no longer supported. Added Hirsute ## Package archive - PORT: Support libarchive versions without `raw` or `mtree` formats. ## Package chr - FIXED: Make chr work in temporary modules (Pengines, SWISH) ## Package clib - ADDED: uuid\_property/2 to get the version and (for 1 and 2) time stamp of the UUID. - ENHANCED: Always install library(uuid), providing (currently) a random UUID in case the OSSP-UUID dependency was not available for building SWI-Prolog. ## Package xpce - FIXED: gtrap/1 is not a meta-predicate. - ADDED: gtrap/1 to call trap/1 with the graphical debugger. ---
**Author:** ![jan](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/jan/32/4_2.png) [@jan](https://swi-prolog.discourse.group/u/jan)\ **Post date:** [September 3, 2021, 1:09pm UTC](https://swi-prolog.discourse.group/t/ann-swi-prolog-8-3-29/4367/3 "2021-09-03T13:09:27Z")
Oops, forgot to upload. Most of this stuff is scripted, but the MacOS version cannot be built in a Linux container (legally), so I have to login to my Macbook ☹ Uploaded. Should be there in max two hours or immediately from one of the [backend servers](https://eu.swi-prolog.org/download/devel) ---
**Author:** ![jan](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/jan/32/4_2.png) [@jan](https://swi-prolog.discourse.group/u/jan)\ **Post date:** [September 9, 2021, 8:13am UTC](https://swi-prolog.discourse.group/t/ann-swi-prolog-8-3-29/4367/5 "2021-09-09T08:13:03Z")
Looks like a bug. Requires some reorganization, so for now just use dynamic/1 🙂