A fallible function returns a `result` value, built with ok(payload) on success
or err(message) on failure. The caller recovers a value with `try EXPR else {
… }`: on ok the whole expression is the payload; on err the else block runs —
with the failure message bound to `error` — and its trailing expression supplies
the fallback. It is a plain branch on the result's tag: no exceptions, no hidden
control flow, nothing unwinds. is_ok(r) / is_err(r) classify without unwrapping.
Payloads are any i32-width scalar (int/fixed/bool/entity). The feature is
additive and only kicks in when ok/err/try are used, so untouched programs
compile byte-identically (verified) and the C-free bootstrap fixpoint holds.
Complements panic/assert from #8 (the unrecoverable half). The optional
top-level frame `recover` stays deferred (needs a frame-abort mechanism); the
full tagged-union/any generalization is tracked in #1.
Adds the `try` keyword and ok/err/is_ok/is_err builtins across the compiler,
the vocabulary header, JetBrains + TextMate/VSCode grammars, the docs inventory
and pages, examples/library/recover.ludic, and a regression case.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
RFC decision (the split the issue recommended): programmer bugs abort loud and
located; recoverable failures become values. This ships the first half.
panic(msg) prints `file:line: panic: <msg>` to stderr and aborts the process with
exit code 1 — a clear, located error instead of a segfault or a silent wrong
result. assert(cond, msg) is the guarded form: it aborts with `file:line:
assertion failed: <msg>` only when cond is false, otherwise execution continues.
The location is baked in at compile time (the call node carries its source line,
g_src_name carries the file); the message is any string.
Both lower in emit_call to an fprintf-to-stderr + exit(1) + unreachable tail
(assert branches on the condition first). @fprintf and the format constant are
declared on demand (g_uses_panic), so a program that never panics is unchanged —
and the compiler's own source uses neither, so the C-free bootstrap fixpoint holds.
- panic/assert registered as builtins across the vocabulary (ludic_syntax.h, the
JetBrains lexer, the TextMate grammar) and documented (docs/language/builtins/)
- examples/library/errors.ludic covers the success path (asserts hold, program
runs to the end); a panic_case in the suite covers the failure path (non-zero
exit + the located stderr message). x test is now 69 checks.
Deferred: recoverable failures as `try`/`else` values (needs the tagged-union
type system, #1) and a top-level `recover` for the dev game loop.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
