Bootstrap shift/reset to both Python and JS targets. The implementation
uses exception-based capture with re-evaluation: reset wraps in try/catch
for ShiftSignal, shift raises to the nearest reset, and continuation
invocation pushes a resume value and re-evaluates the body.
- Add Continuation type and _ShiftSignal to shared/sx/types.py
- Add sf_reset/sf_shift to hand-written evaluator.py
- Add async versions to async_eval.py
- Add shift/reset dispatch to eval.sx spec
- Bootstrap to Python: FIXUPS_PY with sf_reset/sf_shift, regenerate sx_ref.py
- Bootstrap to JS: Continuation/ShiftSignal types, sfReset/sfShift in fixups
- Add continuation? primitive to both bootstrappers and primitives.sx
- Allow callables (including Continuation) in hand-written HO map
- 44 unit tests (22 per evaluator) covering: passthrough, abort, invoke,
double invoke, predicate, stored continuation, nested reset, practical patterns
- Update continuations essay to reflect implemented status with examples
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
is_primitive/get_primitive now check the shared registry
(shared.sx.primitives) when a name isn't in the transpiled PRIMITIVES
dict. Fixes Undefined symbol errors for register_primitive'd functions
like relations-from.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Previously defhandler routed to sf-define which tried to evaluate
(&key ...) params as expressions. Now each form has its own spec
with parse-key-params and platform constructors.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Mirrors bootstrap_js.py pattern — reads the .sx reference spec files
(eval.sx, render.sx, adapter-html.sx) and emits a standalone Python
evaluator module (sx_ref.py) that can be compared against the
hand-written evaluator.py / html.py.
Key transpilation techniques:
- Nested IIFE lambdas for let bindings: (lambda a: body)(val)
- _sx_case helper for case/type dispatch
- Short-circuit and/or via Python ternaries
- Functions with set! emitted as def with _cells dict for mutation
- for-each with inline fn emitted as Python for loops
- Statement-level cond emitted as if/elif/else chains
Passes 27/27 comparison tests against hand-written evaluator.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
