v0.15.1

A better strategy for constraint solver results in vastly lower constraint
solving times and thus reduced overall compilation times. Large improvements in
code generation resulting in less memory allocations and thus a much lower load
on the GC, yielding much better runtime performance.

The internal compilation of generation C code has been revamped, now more
structured and simplified in many ways, internally making use of the Zig buils
system which in turn unleashes a lot of benefits.

Changed

• release builds now use -O3 and dev builds use -Og [#1270]
• Collection overloading has been removed [#1316]
  • It was previously possible to overload collections like dict / Mapping
  • {} now always means the builtin dict

Fixed

• Faster constraint solver through new strategy [#1316]
  • Evaluates vastly fewer possibilities
  • One application used to take over 10 mins for constraint solving which now
    runs in roughly 10 seconds - woohoo
• New second stage compilation of generated C code [#1249] [#1304]
  • new builder performs "second stage" compilation of the C code that
    actonc generates into object files, archives and executable binaries
  • Built on Zig's Build System, gaining all that it offers
  • Very good caching, dependency detection, up-to-date checking and concurrency
  • Custom compilation to make builder itself portable
  • Compilation can now be more clearly separated in two steps:
    • step 1: actonc compiles .act to .c & .h
    • step 2: builder compiles .c & .h to .o & .a & executables
  • Up-to-date checking in actonc adjusted to only compare .act with .c &
    .h output
  • builder does a fantastic job of following dependencies (looking at
    #include statements etc) to figure out when things need to be recompiled
  • All of this is internal, actonc calls builder under the hood, much like
    it earlier called cc under the hood
  • --no-zigbuild can be used to force old compilation method
    • --no-zigbuild will be removed in the future
• Much faster build of Acton itself using prebuilt libActonDeps [#1279] [#1282]
  • Uses a checksum of git refs of all lib that constitutes libActonDeps
    • If any dep lib is updated to use new version, libActonDeps will be rebuilt
  • Uploaded to github.com/actonlang/libactondeps and downloaded on demand from
    normal Makefile, thus used for local builds and in CI
  • Falls back to local compilation if prebuilt version is not available
• builtins, RTS & stlib now organized as an Acton project called base [#1309]
  • More streamlined towards imagined design of how project dependencies will
    work in the future, meaning less special kludges
  • Cleans up include paths and similar, avoiding potential naming conflicts
• builtin code is now generated [#1256] [#1260]
  • __builtin__.c and __builtin__.h are now generated from __builtin__.ty
    at build time, whereas they were earlier checked in to git, having once been
    generated but heavily modified by hand
  • given complexity of these files, it is difficult to keep the files up to
    date when there are changes to the CodeGen pass in actonc
  • actonc CodeGen pass is now infused with some of the bespoke customizations
    done for builtins, other customizations have been removed to streamline the
    whole thing or inserted into .ext.c file to use the "standard way of
    customization" (what an oxymoron)
• Better performance through code generation improvements [#1263] [#1274]
  • Code generation has been improved, primarily to avoid unnecessary
    allocations, thus reducing pressure on GC, leading to improved performance
  • One application that ran in > 12 minutes now run in < 2 minutes
• xml module now correctly parses default namespace [#1262]
• address xml bugs with more null checks [#126]
• Switched to a nightly version of zig [#1264]
  • pre-release version of zig v0.11
  • we still pin to this particular zig version which goes through the Acton CI
    testing so there is relatively low risk of this silently breaking something
• Document after and encourage not using sleep [#1269]
• actonc now transparently passes through zig output [#1277]
  • treats subprocess output as bytestring instead of trying to decode it
  • we only pass it through anyway, there is no analysis done on it
  • avoids errors seen when not using UTF-8 locale, like when LANG is unset
    (effectively defaulting to C)
• Remove bunch of old code, irrelevant tests, old gen env scripts ect [#1278]
• math module switched from stub style to .ext.c style [#1309]
• Add missing MacOS headers [#1309]
• Remove note on segfault in AbE that's no longer valid [#1303]

Testing / CI

• Added macos-13 as test target in CI [#1258]
• New CI job to build libactondeps and upload to "cache" repository [#1283] [#1284]
  • Also using cached for CI builds (as well as local)
  • MacOS CI builds 12 -> 6 minutes, Linux ~8 -> 4 minutes
    • brew-macos is still slow, but we get quicker feedback of failures looking
      at test-macos & test-linux jobs
• Fixed Homebrew build by applying workaround
  • Broke due to upstream changes and is still broken with default suggested
    config in brew new-tap