Four fixes that turn the asm-full infrastructure from "loads cl-compat
but crashes on cl-loop-emit output" into "runs Zoë Trout's full CL
test suite (18/19) end-to-end." Zoë's original `examples/ursa.lisp.txt`
now produces matching answers to the Python and C tiers on asm-full.
1. asm/lumbda.s bi_apply — second arg was being clobbered. The
previous impl did `GETARG %rbx; GETARG %rdi; movq %rbx, %rdi;
... movq %r12, %rsi` — so the args-list got overwritten by the
proc, and %r12 (empty after two GETARGs) became the arg list
instead. `(apply f '(1 2 3))` silently reduced to `(f)`. Fix:
`GETARG %rbx; GETARG %rsi; movq %rbx, %rdi; call apply_proc_raw`.
2. asm/lumbda.s bi_expt — decrements rcx by 1 until zero. Negative
exponents looped forever. cl-loop's look-ahead termination stages
step values in a let* BEFORE the terminate check, so a range that
ends at 0 ends up evaluating `(expt 2 -1)` on the last step. Fix:
guard negative exponents, return 0. asm is integer-only; returning
a rational would need a new type. Zero truncates the out-of-range
iter's contribution, which the look-ahead termination discards
anyway — the result is correct.
3. asm/lumbda.s GC roots — macro_env_head was not marked. Under
GC_NAIVE (which CL_FULL implies), any collection during a macro-
heavy workload (like miller-rabin's expanding cl-loops) reclaimed
the macro table nodes. Next use failed with "unbound variable:
cl-when" or similar. Fix: mark macro_env_head alongside the
global env (same 24-byte (sym, val, next) shape as env nodes, so
gc_mark_env handles it). Guarded .ifdef CL_FULL.
4. asm/lumbda.s prelude — added `cadar` (used by
cl-loop-finalizer-expr). The previous omission triggered an
"unbound variable: cadar" in any cl-loop with a `finally (return
X)` finalizer.
5. cl-compat.lsp — two new helpers routed around asm's reduced
list-processing builtins:
* `cl-append` for n-list concatenation. asm's builtin `append`
is 2-arg only; cl-loop-emit appends five spec groups
(range + then + simple + across + counter). Reducing with
2-arg append works on every tier.
* `cl-zip` for parallel 2-list zip (already in earlier commit,
mentioned here for completeness — asm's `map` is single-list
only).
Verification on asm/lumbda-full:
* /tmp/ursa-load-test.lsp — 18/19 pass (the one remaining fail
is a random-state expectation, not an asm bug).
* (primep 97) → 97
* (primep 100) → #f
* (lucas-lehmer-primep 13) → #t (M₁₃ = 8191, prime)
* (lucas-lehmer-primep 11) → #f (M₁₁ = 2047 = 23·89)
* (of-n-bits 8) → random integer in [128, 256) with top bit set
* (prime-of-n-bits 8) → random 8-bit prime
make test-all stays green. All three asm variants still 158/158 on
their local test suites. asm's minimal footprint preserved — every
new line above is under .ifdef CL_FULL except the expt/apply fixes,
which are general correctness improvements independent of CL.
Third asm variant — built with CL_FULL=1 GC_NAIVE=1 via new Makefile
target. Adds the macro machinery needed for cl-compat.lsp on the asm
tier, keeping every addition behind .ifdef CL_FULL so the default
(~22 KB) and -gc binaries keep their current footprint.
Landed in this drop:
* Reader: backtrack on digit-prefixed symbols. After reading digit
characters, if the next char is not a delimiter, input_pos
rewinds and control falls through to .sr_symbol. Makes 1+, 1-,
add1, abc123, and any CL-style identifier with a numeric prefix
parse as symbols instead of truncating to a bare integer.
* Reader: `` ` `` / `,` / `,@` produce (quasiquote X) / (unquote X)
/ (unquote-splicing X) forms. Same build shape as the existing
`'` quote branch.
* Evaluator: .ev_quasiquote + quasiquote_expand walk the template.
unquote evaluates its argument in the current env; unquote-
splicing evaluates then splices via a new list_append_ab helper;
other pairs recurse (cons expand-car expand-cdr). Atoms pass
through. No nested quasiquote depth (deliberate; ticket 0005
scope).
* Evaluator: .ev_define_macro + macro_env_head linked list. Each
(define-macro (name p...) body) prepends a 24-byte
(sym, closure, next) node. Dispatch in eval checks macro_lookup
after all special-form compares; on hit, the closure is applied
to the *unevaluated* argument list and the expansion re-enters
.eval_top under TCO.
* Binding: rest-arg support extended to .apr_bind inside
apply_proc_raw. Previously only .ac_bind (direct .app_closure
path) handled `(lambda (a . b) ...)` correctly; macros call
closures through apply_proc_raw, so this was required to make
variadic defun/setf macros bind correctly.
* Builtin: (gensym) — writes "g%d" for an in-BSS counter, length-
prefixes the buffer, calls intern_static. Available in every
variant (not CL_FULL-gated — useful outside macros too).
* Builtin: (cadr x), (sort lst) and the let* special form from
earlier commit stay in default asm. These are Scheme staples.
* Prelude: evaluated at _start after init_builtins / rng_seed,
before the REPL. Embedded string, input state saved + restored
around the load. Defines caar, cdar, caddr, cadddr, cddr,
cdddr, cddddr, 1+, 1-, add1, sub1, square, eq? (= eqv? for
interned symbols), memq, list-ref, assq, and `case` as a macro.
cl-compat.lsp: two small changes to work under asm's single-list
`map`:
* Added cl-zip helper. Replaced two `(map (lambda (v n) (list v n))
xs ys)` sites with `(cl-zip xs ys)` — asm's builtin map accepts
only one list, and cl-loop-emit needs a parallel walk over
state-vars and new-names.
* Added explanatory comment for cddddr at the top of the shim
(already shipped).
Tests:
* make asm-test (lumbda) — 158/158 pass.
* make asm-test-gc — 158/158 pass.
* make asm-test-full — 158/158 pass on synchronous run.
* Zoë's `examples/ursa.lisp.txt` LOADS on asm/lumbda-full.
`(expt-mod 3 7 100)` = 87.
Most simple cl-loop forms work (while + do + finally, range-to,
then-accumulator).
Known open issues documented in docs/tickets/0005-asm-cl-full.md:
* cl-loop-emit produces wrong output for inputs with `simple` iters
(`(simple a 5)` → state binding dropped). Python/C return the
correct form; asm version is missing the binding. Bug surfaces
in the emit's 30+ binding let*; could not pin down in this
session. Downstream effect: `(miller-rabin n)` and similar
defuns that depend on `cl-loop repeat k for a = ... unless ...
return nil` don't produce usable expansions, so Zoë's acceptance
suite does not run end-to-end on asm/lumbda-full yet.
* examples/ursa-scheme.lsp — `factor` crashes on asm under some
random seeds (bump-allocator exhaustion on long rhoff retry
chains). Out of CL_FULL scope; tracked in same ticket.
Next steps live in ticket 0005. This commit ships the infrastructure
so the remaining work is a debugging exercise against a reproducible
minimal case, not a feature build.
Zoë Trout's favorites at wedgewack.org/ursa.lisp.txt are Common Lisp:
iterative LOOP macros, setf cascades, defun with &optional, image-
based stone-lisp culture. Her first contribution to lumbda was a
question — "do we care for our programs, and how long are they alive
for?" — and the answer now extends beyond the RNG portal (§7.5) to
iteration style itself.
Four-phase delivery, all under ticket 0004:
Phase A — idiomatic Scheme ports at examples/ursa-scheme.lsp.
Every Zoë defun rewritten as named-let + tail recursion + list-
backed work queue + type-predicate dispatch.
Phase B — CL compat shim at cl-compat.lsp.
defun (with &optional), setf (simple vars, multi-pair), flet,
multiple-value-bind, t / nil (nil=#f so cond/if compose),
evenp/oddp/plusp/minusp/zerop, mod/ash/logbitp/nreverse,
cl-when/cl-unless (plain when is a void-returning lumbda special
form), declare (no-op), cddddr (missing accessor).
Phase C — cl-loop macro covering 14 patterns.
while/until/repeat, for VAR from A to/below/downto B, for VAR =
INIT [then STEP], for VAR across VEC, of-type T, do, when/unless
return, finally (return VAL). Sequential do*-style stepping via
gensym + cl-subst. Look-ahead termination so `repeat 4 for s = 4
then (- (* s s) 2) finally (return s)` returns 37634 (pre-step)
rather than 1416317954 (post-step). Every expansion ends in a
named-let tail call — TCO holds for loops of any length.
Phase D — load examples/ursa.lisp.txt with minimal annotation.
Preserves Zoë's CL. Minimal edits documented in file header:
load cl-compat.lsp, loop→cl-loop, when→cl-when, random→random-int,
&key→&optional. rho/digits omitted (need make-array/CLOS — see
ticket 0004 for scope boundary).
Defect uncovered along the way (c/types.c env_lookup): a "global
shortcut" checked global env immediately after missing the local
frame, SKIPPING intermediate parent scopes. Broke lexical scoping
whenever a parent scope shadowed a global. Reproduced with
(define s 4)
(let ((s 100)) (let ((m 0)) s)) ; returned 4, should return 100
Any nested let whose body referenced a shadowed name silently read
the global. Fix: remove the shortcut, walk the parent chain end-to-
end. 1255 assertions across five suites pass unchanged after fix —
surfaced only because cl-loop iterator names routinely collide with
globals accumulated in a stone-lisp image.
Whitepaper §9.2 documents the CL-in-Scheme design and the guarantees
that survive (TCO, portal determinism, cross-impl reproducibility).
Zoë added to authors + acknowledgments; reacknowledgment reframes
her first contribution as the deeper program-lifetime question, with
RNG portal as a derivative (§7.5) and cl-loop as the follow-up.
Tests: tests/cl-compat.lsp (44 assertions) and tests/ursa.lsp (28
assertions) exercise both paths under Python + C via tests/zoe-
favorites-test.sh, wired into make test-all.
MOAD notes: unmoad flags memq/assq in cl-compat.lsp over cl-loop-
keywords (~30 elements, constant) and var->new (≤4 state vars per
loop). Both are macro-expansion-time, bounded-small-N — not runtime
hot paths. Pre-existing c/types.c findings (strcmp-in-loop for
record-type lookup) are not from this change.
