uiop/image

uiop/image is what a program does at its edges: end the process with a status code, report a condition nobody handled, and register work to run when an image is restored or dumped. 25 of the 30 exports are implemented; the five that are not are the command-line family, named at the bottom of this page.

Every name is reachable through either spelling: uiop:quit and uiop/image:quit are the same function (The uiop Package).

Three decisions here are rontolisp's own, and each is a decision rather than a gap:

• uiop:quit is the host's exit on all four backends, and nothing runs after it — see Exiting.
• Backtraces carry no frames. No backend keeps a Lisp-level call stack, so the honest rendering of "the backtrace for this condition" is the condition and nothing else. Real UIOP's own fallback for an implementation without a backtrace API has the same shape.
• There is no image to dump, restore or create, so those three signal — but the hooks around them are real, because registering into one is just a list push. See Image hooks.

Exiting

$ cat quit.lisp
(print :before)
(uiop:quit 3)
(print :after)
$ rontolisp quit.lisp
:BEFORE
$ echo $?
3

The same program compiled to a class, to a Preview 1 module or to a component prints the same line and exits 3: the primitive underneath is System.exit on the JVM, proc_exit on WASM Preview 1 and wasi:cli/exit's exit-with-code under --component, and the interpreter raises an exit signal the CLI turns into the process code.

Two consequences follow from that being a real host exit, and they hold on every backend:

• Nothing runs afterwards. An unwind-protect cleanup around a quit does not run — the process ends where the call stands.
• It is not a condition. handler-case, ignore-errors and a catch tag cannot see it, so a quit inside a library's error handling still quits.

The status code is masked to eight bits, which is what a POSIX host does with it anyway and what wasi:cli/exit's u8 accepts: (uiop:quit 300) exits 44 everywhere rather than 300 on one backend and 44 on another.

A test runner's exit code is the usual reason to reach for this:

$ cat run-tests.lisp
(uiop:quit (if (rove:run :my-app/tests) 0 1))

uiop:quit needs a host process to end, so it is refused at compile time under --no-wasi and --no-gc: those emit a reactor whose entry points are exports a host calls, and a reactor returns from an export rather than exiting.

Fatal conditions

A fatal condition is a serious-condition — the type is a deftype alias, so typep and a handler-bind clause both match it.

uiop:*lisp-interaction* is nil here where upstream defaults to t. It asks "is this an interactive Lisp environment, or is it batch processing?", and every rontolisp backend runs a program and ends: there is no debugger to enter and no REPL underneath a compiled artifact. That value is what makes uiop:handle-fatal-condition report and exit rather than call an invoke-debugger that does not exist.

$ cat fatal.lisp
(print :start)
(uiop:with-fatal-condition-handler ()
  (error "the sky is falling"))
(print :unreachable)
$ rontolisp fatal.lisp
:START
Fatal condition:
the sky is falling
the sky is falling
the sky is falling
$ echo $?
99

The condition appears three times because upstream prints it three times — once as the report, once with the backtrace, once as die's message — and the middle one has no frames above it here.

Backtraces

:count is accepted and ignored: there are no frames to limit. lack-middleware-backtrace is the library that reaches for this — its error report opens with uiop/image:print-condition-backtrace, and here that report is one line long.

Image hooks

The hooks are real even though nothing here can dump an image: a library may register into one while it loads, and that must not be an error.

uiop:*image-dumped-p* is nil and stays nil — nothing sets it, because nothing dumps.

Dumping an image

rontolisp has no image in the SBCL sense. A program is read and run, or read and compiled into one artifact:

rontolisp app.lisp -o App.class      # a JVM class
rontolisp app.lisp -o app.wasm       # a WASM module

which is what uiop:dump-image would have been for.

What is missing: the command line

uiop:argv0, uiop:command-line-arguments, uiop:raw-command-line-arguments and uiop:setup-command-line-arguments are not implemented yet: they signal uiop:not-implemented-error like every other unfilled uiop name, and uiop:*command-line-arguments* is nil. A program that needs input today reads it from the environment (uiop:getenv) or from standard input.