The first is CLHS 9.1.4.1: a clause that signalled the condition it handles used to re-enter itself until the stack ran out. The stale list now names a lifted clause by the function it is written in, and BUILT.md's cost line is measured against master.
Removal marks a deleted slot unless no probe can have passed it, and a rebuild at the same capacity sweeps them. The header, the entry points and the iteration contract are unchanged. A Map has no bounds check, so the entry asking to convert one is closed with nothing to convert.
A dev cell carries its body's signature word beside the body, every call through a cell (and every function value taken from one) compares it with the word the site was compiled for, and the session lists the stale callers by file and line on the reply. Both backends, both installers; release builds have neither the word nor the compare.
x86 built a settling right-hand side straight into its destination, so (set p (P {.a (.b p) .b (.a p)})) wrote .a and read it back for .b. assign now also asks whether the value reads storage the destination lies in, and goes through the temporary when it does. The global-initialiser entry was already closed by startup_plan's Set; the unrooted-temporary entry turns out to be a both-backends rooting gap and stays open for a decision.
FIX.org, NEXT.md, DISCUSS.org, docs/DISCUSS.md and the session handoff at the
root are one TODO.org now: 293 entries under seven subsystem headings, each
carrying an org keyword that says where it stands. A DONE entry is a few lines
saying what was decided and what that rules out; the reasoning that would not
compress — the embedding spike and the four reports the hand-written x86
backend was built from — moved into docs/BUILT.md instead, and its entries
point there in one line.
Every entry was checked against the tree before it got a keyword, and the
prose was wrong in both directions. Things the deleted files called open were
built: the first-evaluation stall, main being redefinable, macro parameter
lists, the type-limit constants, the array constructors, the byte fills,
inc/dec, the discard's fontification, the Emacs buffers, rt_die's _exit, the
backtrace surface, and the acceptance failure that could print and still exit
zero. Things they called done were not: the backend reports' no-plan buckets
had gone stale in the other direction, the value-dependent defvar was
superseded rather than built, and macro-expansion source locations are on an
unmerged lane, so that entry is NEXT and names the branch.
Every comment that cited one of the five by name now cites a heading that
exists, in TODO.org or in docs/BUILT.md. The session reports under
docs/handoffs/ keep naming the files they worked on, because rewriting them
would falsify what those sessions did; each carries a note saying where the
content went.
Review found it, and it is a silent miscompile on both backends rather
than a refusal anywhere. mangle_ty flattens a whole signature into one
hyphen-joined string, so (CFn [(Ptr i32)] i32) and (CFn [ptr i32] i32) --
the second over a struct someone called ptr -- flatten alike; keyed on
that, the second widening reused the first's thunk at the wrong arity.
The key is the types now, compared with Types.equal, and the symbol is a
counter over the thunks already minted, so nothing is derived from a
spelling. fn-thunk-share.flan is the pair, and it prints 5 and 17.
And a regression beside it: a generic whose function parameter binds the
type variable. (defn apply2 [f (Fn [$t] $t) x $t] ...) called as
(apply2 bump 1) compiled before this lane and stopped, because bind_ty
had no arm admitting a CFn argument at an Fn pattern -- and once it had
one, the call still handed one word to an instance declaring two, because
a parameter that still mentions a variable is checked with no expectation
and expect never sees the pair. Both halves: the arm, and the widening
in generic_call's catch-up pass beside the numeric one. The same gap hid
new functionality -- a CFn argument at a (CFn [$t] $t) parameter had no
arm either -- and mentions had no CFn case, so bound_exactly answered
wrong for a variable living only inside one.
The corpus missed all of it because the prelude binds $t from an earlier
argument, so the parameter is concrete before bind_ty sees it.
While here: escaping's enumeration is the *clean* set now rather than the
suspect set. It had a hole where a list like that cannot -- an (at s 0)
over a slice of Fn read as clean while the Vec, struct and pointer
spellings were refused. Unreachable today, and the header claims the
list is closed. The same inversion fixes which refusal message an index
read gets.
Three minors: Anull was defined and never constructed; the capture-dyn
message substituted a descriptor into a noun slot; and session.ml
rendered a defn's changed signature as (Fn [...] ...), which is now a
real type and not the same as (CFn [...] ...) -- it writes the parameters
and the return the way a defn writes them.
And one rounding corrected in the docs: handler-bind is not free for a
program that captures nothing. %handler grew from 24 bytes to 32, every
push writes a null into the new field, every clause gains ptr %env with
an alloca and a store, and flan_signal passes one more argument per
dispatch -- twenty changed x86 lines on loops.flan. Small, real, and
paid by every conditions program.
The four refusals the function-value lane wrote down are now three and a
half: capture is a feature, the escape is the refusal in its place, and a
struct field or a global of function type is refused for the same zero as
before with a sharper reason behind it. The handler note is amended
rather than deleted -- its reading was right, and saying so is worth more
than a clean paragraph.
The convention section carries both rulings, the name and every name it
beat, the warning that CFn is not C interop today, the four reasons to
reach for it, what was measured rather than asserted about an ordinary
defn, and the wasm32 finding that killed the first design -- being
exactly typed is checkable by a verifier and the alternative was an
argument from a calling convention.
FIX.org carries the rulings verbatim, what the escaping lane inherits and
changes, the thunk's environment holding a code pointer rather than a GC
object, and two things recorded and not built: a CFn under a future
--no-conditions reaching C's exact convention, and CFn in a struct or a
fixed array, which ZII refuses and capture has nothing to do with.
Two bugs, both in lib/x86.ml, both reached by signalling a condition from
inside the value being assigned.
The backend has no register wide enough to hold a struct, so it built every
aggregate in its destination, element by element as they were computed. A
transfer out of the middle left the destination in the middle: a global of
four numbers read part old and part new, and so did a local, a struct field,
an array element, a place behind a pointer. A union case was worse than the
rest, since its destination is zeroed before the fields are written.
The second one only looks like the first. An aggregate result is written
through a hidden pointer the caller supplies, and the transfer exit zeroed
that result on its way out, on the correct reasoning that the caller never
reads it. At (set g (f)) the pointer is g, so it zeroed the caller's
variable. It zeroes scalars only now — and with the first half in place
nothing reaches it, so that one is defence in depth and FIX.org says so
rather than claiming a test it does not have.
Assignment builds into a frame temporary and copies, which is the shape
emit.ml always had. The copy is paid where it buys something: [settles] says
whether lowering an expression is bound to reach the end of it, and a
right-hand side that settles is still built in place. That includes a
conversion, except the one direction that is checked — a float narrowed to an
integer — because an array of this language's literals is written
[(u32 1) (u32 2)] and refusing every cast would have taxed the commonest
aggregate there is. A let pays only inside a loop, because a slot reached
once per frame is recorded as bound after the value lands.
half-write.flan is every destination crossed with every right-hand side, run
on both backends, with a scalar row so a regression in one is not read as the
other. dev-halfwrite.flan asks the break loop the half a running program
cannot ask itself: the local, which is invisible to the program and plain to
an editor reading the frame.
The def-edit paragraph in docs/BUILT.md described this as open and is now the
claim it was waiting for. FIX.org records the two lanes the review of this one
turned up and this one does not take: an aggregate built in place can read its
own destination, which is an aliasing question rather than a transfer one; and
the temporary is a frame buffer no root table names, which matters the day a
struct may hold a dyn field.
Follow-ups to the re-run flip, and all of one kind: each said something
correct about a committed re-run that still read as parked, and the flip made
it false.
flan_merged_park's note that the program stays PROGRAM_PARKED across a poll is
now true of every round but the one it leaves on — which is the round that
drains the ring with a run already taken, and the round the fix's own argument
leans on as the long one.
Program.rerun's refusal told the reader to close a window or let the program
finish. With a thunk stopped in the break loop a re-run is accepted, the state
goes running, and a second is refused by that sentence — advice about a game
loop for somebody whose thread is in a break. The C cannot see a break; this
end can, so Dev.rerun passes what it already asked the agent and the refusal
says resume or abort instead.
The five-second timeout in eval_expr and run_render_thunk reached its
break-loop sentence through the Parked arm, so a program stopped between runs
was asked whether it calls (agent/poll). Both gain the arm that names the
break. run_render_thunk's two sentences become a function first: the new one
asks the agent, and that was the body of a five-millisecond tick.
docs/BUILT.md gains the case an editor author meets — :parked nil :stopped t
with no frames running — and FIX.org records that test_dev.ml:763's refusal
assertion was racy before this and is narrowed by it.
--dev --sanitize had been unbuildable for as long as a dev build has
armed the registry from a constructor, and nobody knew because no alias
built it: test_sanitize built the corpus twice and neither time --dev,
test_dev builds --dev and never with a sanitizer. A configuration
nothing builds can be broken for a month, and that one was. af71459
fixed it; this is what keeps it fixed.
dev_sweep, in the alias that already exists rather than a new one --
five names to remember was already four too many, and this is the same
question @sanitize is for. Seven programs built --dev twice, plain and
sanitized, run standalone with no daemon: a sanitizer report fails, and
so does any divergence from the unsanitized dev run.
Standalone is what makes it nearly free, and it works because a dev
build is not a dev session. The cells, the marker and the constructor
are in the executable either way, and a program that never calls
agent/start runs to its own end. That is why the list is mostly
ordinary programs built the other way: dev-noagent is the only one of
sixteen dev-*.flan that does not import the agent, and the rest stop in
the break loop waiting for an editor, which is test_dev.ml's business
against a real daemon.
The three dyn programs are not interchangeable and the difference is
the collector. dyn-vec allocates and never collects -- flan_dyn.c has a
one-megabyte floor and dyn-vec does not reach it -- so what it says is
that the registry and the allocator agree. dyn-map and p13-dyn-collect
are the only two programs anywhere past that floor, so they are the
only two under which a mark and a sweep run; without them a collection
had still never happened in a dev build under ASan.
dev_segv is beside the sweep rather than in it, because the program
that faults cannot be compared against an unsanitized run: that build's
handler prints its line and parks in the break loop, so the plain half
would hang, and the two are supposed to differ. ASan is meant to own
the fault -- flan_dev_crash_enable checks a weak __asan_init and stands
down -- so the case asserts ASan's report and the absence of the
handler's line. At -O0, because at -O2 the write through a bytes-view
of a literal does not fault at all and both builds print the string
unchanged. That yield had never run in any build anywhere; it was
behind a link that did not happen.
Checked both ways rather than asserted: eight failures with the
constructor naming declarations again, clean with it fixed.
Twenty-six seconds of the alias's 2m30 warm, and nothing added to dune
test.
Two aliases were also green only because dune test runs first.
@sanitize never listed the package directories pkg-diamond.flan
imports, and @page never listed sand.flan, which quotes.sh reaches
through sand-headless.flan; from a cold tree the first died before its
first sanitized build, and @page sits inside @checks where CI hides the
same thing. Both listed now. @valgrind, @x86, @js and @cells were
checked and are complete.
What it still does not reach is in FIX.org: a program driven by a real
flan dev daemon under ASan, which wants a --sanitize the CLI does not
have and a way through Dev.serve. --x86 --sanitize is refused by Build
by name, so there is no second backend to track here.
flan_merged_rerun accepted a request under the lock and left program_state
as it found it: PROGRAM_PARKED, until the parked thread got round to waking.
describe's :parked reads that same state, so a caller that asks for a re-run
and then waits for the program to park again was liable to be answered by the
park it had just ended — the wait fell through on the old park, the next
request went out before the first run had started, and the pair of them made
one run between them; or the thread woke in between and the second was refused
as "already running". One lagging state, two symptoms, and all four of
test_dev's re-run sites could show either under load.
The window was documented over flan_merged_park as "as wide as a flush". It
stopped being that when the ring drain went in front of the park's exit: the
leaving round loads whatever was queued before it breaks, so the window was as
long as the next thing the program had to do.
The store moves to the acceptance, under the lock that made it. There is no
longer a moment in which a committed re-run reads as parked, and the park's own
store on the way back into main stays as the no-op that says where the thread
has got to. Dev.rerun reads the liveness and the break for its note before it
asks, since afterwards the answer is running by construction.
Measured on that loop driven standalone against programs/dev-rerun.flan: 9
failures in 25 runs under two busy-loop burners before, 0 in 50 under the same
load after. FIX.org, 2026-09-21, has the readers that were checked, the path
that cannot exist, and why the two-process daemon has no such window.
The author: "I think I prefer length over len, because then I'll use len as
the variable name". One arm in check.ml, one row in the table beside it, and
every (len x) in lib, test, examples, vendor, spike, docs, web, emacs,
plan.org and NEXT.md rewritten.
Shadowing and builtin/ had already taken most of the sting out: a (defn len
...) was legal and won in its own file, and builtin/len reached past it. What
was left is that len was still a builtin — the defn earned a warning, and a
wrapper had to say builtin/ at every inner call. Now there is nothing under
the short name: len is an ordinary identifier in every position, which is
what (let [len (length xs)] ...) wants.
length takes over as shadowing's worked example rather than the feature
losing one. shadow-builtin.flan, builtin-qualified.flan, pkgs/shadowed and the
builtin/ rows in test_flan move to it and go on testing shadowing.
A call to a len nothing defines is answered where an unknown function is,
after every table and after the shadowing guard, so a program with its own len
never reaches it. The sentence is said rather than guessed at — len and length
are three edits apart and the did-you-mean's net is one — and the call is
written back out through spell_arg, as-slice's spelling lifted out of it and
now shared, so what is printed compiles.
sand.flan:33 still calls the old name and is the author's to change; until it
does, test_acceptance and test_session abort there. Both were run green
against a copy with that one line changed. FIX.org says so.
[flan_dev_reg_at] still went straight round its walk-level retries — a failed
scan_open and a failed scan_ok both back to the top. It is the one site where
the argument for leaving it holds water, since the agent gates the verb behind
a stopped program and there is no writer to lose to. It loses to the other
argument: it is the same mistake the slot read was making, three lines under
the note explaining why it is a mistake, and a bare retry left next to that
note teaches that the rule has exceptions it does not have.
And the cost of a refusal was written as a bound when it is a typical. "One
writer, so at most one slot of a walk is odd" is true at any instant and false
across a walk — flan_reg_compact writes every slot under its own counter, so a
repeatedly preempted writer can charge the full patience against several slots
of one walk, 4096 of them in the arithmetic worst case. Both docs now say
typical and give the worst, and record what the larger figure means for
request_lock, which is held across handle_line: a refusing listing delays an
abort by that much. Nothing depended on the old number.
Also written down, because it is the clearest statement of why this was not a
timeout: sixty-four bare re-reads of one word finish in about two microseconds,
so against a writer a millisecond from running the old budget was not short, it
was zero wall-clock.
Green runs of a load-only flake, taken on an idle machine, are worth nothing,
and a count alone cannot tell you which kind you have. So the load for the
55-run test_reload proof was a build of flan_dev.c from the commit before this
fix, churning beside it: a positive control as well as a load. It refused 4151
of the 50478 runs it managed in that window — 8% — while test_reload went 55
for 55. Paired on the direct binary too, eight copies at a time: 13 of 80
before, 0 of 160 after.
Also here: the bound BUILT.md used to quote went from two milliseconds to about
sixty-six, and the doc says so rather than dropping the number; the note that
flan_dev_reg_at shared the spin and could answer "never heard of this address"
under load; and the verdict on the two neighbouring dev flakes, which are three
causes and not one.
