Source src/silo:std.effects.panic

1##! Panic effect and intrinsic.
2##!
3##! `panic` is a free `:fn` of stack effect `( Str -> Never )` wrapping
4##! the host intrinsic — it is not an effect op. `PanicInfo` captures
5##! a panic as a record of message, location, and backtrace (location
6##! and frames are `Str` placeholders until structured `Location` /
7##! `Frame` types land).
8##!
9##! `+Panic` declares `.catch` and `.resume-unwind`. The host currently
10##! ships only the default abort-on-panic handler, so `.catch`
11##! terminates today; real handler plumbing arrives with the
12##! effect-handler infrastructure.
13
14:use
15  :open core Never Str Vec Result
16:end
17
18# si[impl effect.panic.info+1]
19## Panic payload: message, source location, and a sequence of backtrace
20## frames. `Location` and `Frame` are placeholders (`Str`) pending
21## `spec/reflection.md`'s typed Location and the stdlib `Frame` record.
22:record(pub) PanicInfo
23  .message  Str
24  .location Str
25  .stack    (Vec Str)
26:end
27
28# si[impl effect.panic.decl+1]
29## Observable-panic effect. `.catch` runs a quotation and reifies a
30## panic into `(Result a PanicInfo)`; `.resume-unwind` re-raises a
31## captured `PanicInfo`. The host default behaviour (abort or unwind)
32## applies when `+Panic` is not in scope.
33:effect(pub) Panic
34  .catch         ( [ -> a ] -> (Result a PanicInfo) )
35  .resume-unwind ( PanicInfo -> Never )
36:end
37
38# si[impl effect.panic.intrinsic]
39## Free fn wrapping the host `panic` intrinsic. Stack effect
40## `( Str -> Never )`. Because the return type is `Never`, a `panic`
41## call type-checks in any position that expects any type — see the
42## never-coercion rule in `spec/types.md`.
43:fn(pub) panic ( Str -> Never ) panic-intrinsic :end