Sword 0.2.1 — Fold

2026-10-20. A patch to Fold that finishes the way out to C: a library named in the
source and linked either way, a C function as a value, and a library loaded
while the program runs.

What changes for existing programs

• The name of an extern function, used as a value, is an extern func,
  not a func. Code that handed one where a func was expected no longer
  compiles; a func can only point at Sword code, which is what lets det
  follow a call through one.
• An integer narrower than 32 bits reaches C widened. On Apple's arm64 an
  extern taking an int8_t, an int16_t or a bool read whatever the upper
  bits of the register held.
• Every function but main is internal to the program. LLVM drops what
  nothing calls: on an Apple M4 a hello world went from 145 376 to 119 400 bytes
  and the HTTP test from 281 752 to 168 552, and building the latter takes about
  half the time. A program that uses part of a package no longer references the
  C symbols the rest of it needs.

C

• extern "z" func ... names the library a function comes from, and it is
  linked without being mentioned on the command line. pkg-config is asked where
  it is when the machine has pkg-config.
• shield --static links each declared library from its archive and refuses
  to build without one. The system's own libraries stay dynamic.
• extern weak func ... — a function the program can run without. Its name
  is an ?extern func, to be checked before it is called.
• extern func(T) R — a C function as a value. A Sword function converts to
  one, which is how qsort gets a comparison; an address converts to one, which
  is how a loader's answer gets a type.
• std/dl opens a library while the program runs, finds functions in it,
  and keeps the system's own account of what went wrong in Loader.Why().
• --emit-link prints the rest of the link line, for a build that links by
  its own means.

Other machines

• --target=<triple> builds for another 64-bit, little-endian machine,
  against a runtime built for it with make TARGET=<triple>. -c stops at
  the object file and needs nothing but clang.

Fixes

• shield test on a program — a package with a main — failed in clang every
  time (#4).
• A function can return a function value; the parser read the result type as
  the start of the body.
• Two copies of the test suite on one machine no longer overwrite each other's
  certificates, files and test binaries (#36), and shield test no longer puts
  a binary beside the package for the length of a run.
• The value of shield test -p reached the shell unquoted.
• -sim warns about a call through an extern func, as it does about a call to
  an extern declaration.