2026-08-07: Fuzion August Update

We have started preparing a first release of the feeze scheduler tracer and setting up feeze.dev as a project website. We are happy to receive your feedback!

• General

  • Important changes to the Fuzion team:

    • Simon von Hackewitz has successfully finished his training as Fachinformatiker Anwendungsentwicklung in June and has joined our team as a full developer in July.

    • Artur Dmitriienko started an internship on first of August with the goal to become our new trainee Fachinformatiker Anwendungsentwicklung from September.

• Fuzion language

  • Anonymous inner features like _ : a is ... may no longer inherit from several features as in _ : a, b is ...: add error for anonymous feature with multiple inheritance calls (#7378)

• Base library

  • New library features

    • add mutable dynamic arrays, that can grow/shrink (#7249)

    • Add POSIX clocks and use them for timeouts in blocking_mutate.wait (#7376)

    • add short_circuit effect to allow early return with result (#7326)

      To use this, you can now write, e.g., as follows

      say <| flow.short_circuit (option i32) .run ()->
        (1..100).for_each i->
          if i=42
            (flow.short_circuit (option i32)).env.return i
        nil
                

    • add Unbuffered Channel for channels that do not buffer data (#7266)

      This is used to implement go-style channels created via ch := concur.channel TYPE with blocking operations to send ch<-val and receive <-ch data.

    • Map.as_mutable_map add default implementation (#7297)

    • os: add basic support for creating pipes (#7156)

    • add effect native_access to denote access of native code (#7397)

  • Changed library features

    • Add precondition to concur.blocking_mutate.wakeup_next_in_waiting_list (#7352)

    • allow repeated calls of os.process.wait while process is running (#7334)

    • better error for failing switch.or_panic (#7406)

    • call finally for default effects instated at big bang. (#7330)

    • enhancements to file.meta_data (#7283)

    • fix effect annotation in Unbuffered_Channel (#7351)

    • fix NullPointerException during error output (#7407)

    • make Mutable_Hash_Map thread-safe (#7294)

    • fix naming convention issues (#7332)

    • move has_interval to property.interval (#7336)

    • move path to io.path (#7388)

    • move send_signal to Process effect (#7396)

    • Mutable_Hash_Map use num.fraction instead of f32 (#7302)

    • rename eff as flow (#7335)

    • rename time.duration.times to time.duration.scale (#7409)

    • synchronize read access to concur.Thread.park_condition, fix #7320 (#7350)

    • threads effect, default_value, do not include self in running/child threads (#7331)

    • use function to initialize mutable array instead of single value (#7399)

    • fix occasional “process not in set of running processes” (#7377)

    • time/frequency: fix case of infinite period multiplied by zero (#7445)

    • time/period: for infix * document behavior for case n = 0 using a post condition (#7446)

    • change effects to ref-effect removing the handler

      • convert delete effect to ref-effect removing Handler (#7371)

      • convert envir.args to ref-effect (#7362)

      • convert move effect to ref-style removing Handler (#7370)

      • convert stat effect to ref-effect, removing Handler (#7372)

      • change nano to ref-effect removing Nano_Time_Handler (#7359)

      • change writer to ref effect Writer removing Handler (#7355)

      • convert random effect to ref-effect, removing Handler (#7361)

      • convert Seek effect to ref-style, removing _Handler (#7393)

      • convert Unique_Id and env.Vars effects to not use Handlers (#7347)

      • make exit a ref-effect (#7365)

      • make process a ref-effect, remove handler (#7366)

      • update Threads effect to ref-style, removing _Handler (#7389)

      • update dir.make to ref-effect style, removing Handler (#7373)

      • remove some more env short-hands (#7276)

  • Removed library features

    • remove confusing effect instatement feature infix <- (#7403)

    • remove String.type.from_mutable_array (#7303)

• Other library modules

  • realtime module

    • add abstraction for a scheduler (#7270)

    • adjust comment after move to realtime (#7349)

    • fix static assertion failure on macOS (#7432)

  • tokiwa module

    • tokiwa: fix record_process, always close stdin even when no input provided (#7360)

    • tokiwa: send kill signal to timed out process (#7322)

  • web module

    • parse_url, return proper error if port value exceeds 16-bits (#7384)

    • remove env short-hand (#7383)

• Parser

  • fix require condition when operatorExpr returns Call.ERROR (#7340)

  • fix skipTypeTail to support fully qualified this-types (#7329)

  • fix source position of ternary operator call (#7324)

  • more sourceRange uses instead of sourcePos (#7328)

• Front end

  • fix #7401 by relaxing require condition a bit (#7414)

  • rename, isRelayTypeInCotype as isRelayType (#7316)

  • resolve NYI comment hinting on a potential performance problem (#7319)

  • change λ.call visi to public (#7140)

  • cleanup call result type determination (#7275)

  • consider type features as well for partially applicable features (#7308)

  • fix check-condition logic in Call.cotypeInheritanceCall (#7281)

  • fix resolving type call where targets are QualThisTypes (#7455)

  • fix this-type not properly adjusted to cotype-target (#7263)

  • fix type pars not handed down via targets of inheritance calls (#7398)

  • flag error when user code call <effect>.type.default_value (#7375)

  • Loop, mark successBlock/elseBlock as final (#7342)

  • remove restriction constraint must not be choice (#7395)

  • simplify code in isAssignableFrom a bit (#7422)

  • replace GenericType by ParametricType (#7309)

• Middle end

  • fix error clazz index (#7419)

  • fix isConst detection (#7433)

  • mark lookupFeature as not public (#7442)

  • normalizeOuter, simplify logic (applied de Morgan’s law) (#7333)

• Backends

  • JVM backend

    • be/jvm: callNative, store result of arguments expressions in locals (#7413)

• Tests

  • add regression test for already fixed issue 5264 (#7411)

  • add regression test for already fixed issue 5711 (#7410)

  • add reg test for #4505 (#7337)

  • add test for fixed issue #4510 (#7325)

  • add test for process.kill/term (#7390)

• Benchmarks

  • Modified Jitter so that testing threads send raw data back to the main thread. (#7125)

• Build Infrastructure

  • add timeout to Jenkins pipelines (#7307)

  • fix recording of tests that require input via stdin (#7346)

  • ignore line numbers of .java files when checking examples (#7363)

  • remove obsolete simple_inp.mk (#7345)

  • check_simple_example: pass cpu_time_limit to record_process (#7392)

• Documentation

  • Added Realtime glossary (#7327)

  • Corrections and added more details to the Realtime Manual (#7354)

  • use term “Type Feature” instead of “Type Function” (#7300)

  • update javaDoc comments, use @code instead of backticks (#7280)

• Fuzion Webserver

  • add timeout to Jenkins pipelines (#428)

  • Add target to build and run fzweb from jar file (#437)

  • fix fzweb benchmarks running forever (#429)

  • fix running examples (#440)

  • modernize html, remove <br>s use style instead (#426)

  • src/global: adjust Sieve_Cache usage (#438)

• Feeze

  • Add logo drafts (#19, #27, #25)

  • rec: cleanup stdout output (#73)

  • rec: do not attempt to load libfuzion_rt.so if it does not exist (#75)

  • Documentation

    • add empty manual file (#85)

    • add feeze module ids (#20)

    • add scheduling data screenshot, fix typos (#29)

    • minor fixes in readme (#74)

  • GUI

    • bin: check dependencies when starting feeze GUI: OpenJDK >= 25, libgc. (#21, #23, #71)

    • add desktop file and icon (#26)

    • add UI scale to feeze script (#72)

    • cleanup rename Java package dev.flang.feeze as dev.feeze (#83)

    • Enable desktop start of feeze (#79)

    • show starting... when starting recorder (#77, #78)

    • support changed recorder output: ready instead of Waiting for commands (#76)

  • Build process and GitHub Actions

    • add build scripts for ubuntu 24, 26 and latest and release script for ubuntu 24 (#30, #31, #32, #33, #35, #36, #37, #38, #40, #41, #42, #43, #44, #45, #46, #47, #48, #49, #50, #51, #52, #53, #54, #55, #56, #57, #58, #64, #65, #66, #67, #68, #69, #70)

    • make: add release as make target to build release (#22)

    • make: Add makefile rules to download Fuzion release to use for build (#24)

    • make: use Fuzion rel 0.098 (#28)

    • make: fix typo in error message (#34)

    • make: use /usr/sbin/bpftool (#39)

  • First version of feeze website (#59, #60, #61, #62, #80, #81, #82, #84, #86, #87)

Cheers,

--The Fuzion Team.