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.
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.
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superseded rather than built, and macro-expansion source locations are on an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.
spec-memory.md's case 2, capture by value into a stack environment, and
the calling convention the author's rulings asked for.
(Fn [i32] i32) captures; {code, env}; the common case
(CFn [i32] i32) the bare address; one word; cannot capture
A local of the enclosing function that an fn names is copied into a
struct the checker synthesises, held in a slot of that function's frame,
and the value carries its address; the lifted body reads the copies back
into named slots of its own, once, at entry. So the name in the body
means what the local held at the instant the value was made --
fn-capture.flan changes the local through a pointer after the value
exists and the fn still answers with the old one.
Two types rather than a uniform environment parameter: "while it's dyn
first, static side should never have to pay the price for the existence
of the dyn side... if you fully opt out, for instance, using --no-gc
flag, then we should be operating under Odin/C semantics and never paying
any runtime costs." The environment is declared by exactly the bodies an
(Fn ...) value can reach -- a lifted literal in an Fn position, every
handler clause, and the widening thunks -- and by nothing else. An
ordinary defn emits the signature it always did; calc-me and fourteen
corpus programs were diffed to say so.
CFn, because the C carries information: a value with no environment is
the only kind that could ever cross to C, and under the --no-conditions
direction FIX.org records it becomes literally a C function pointer. It
is not that today -- a declare cannot take a function type at all -- and
crossable's refusal says so where a reader would otherwise be misled.
Nobody needs CFn: Fn accepts everything, and the commonest reason to
reach for the narrow one is that a *named* function handed to an Fn pays
a hop through the widening thunk where a CFn is a direct call.
That thunk is one small function per distinct signature widened, which
reads the bare address back out of the environment and calls it. The
cheaper trick -- the environment last, ignored by a body that never
declared it -- is legal under SysV and is a trap under wasm32's
call_indirect, which compares the signature at the call. Every indirect
call is exactly typed now.
A handler clause captures the same way and is sound with nothing left
over: its frame is popped by the body that pushed it. What is refused
there is a *store* into a captured name -- it is a copy, and writing to
it would leave the local as it was.
And the other half, which is what "non-escaping" means: a value carrying
an environment may be called, passed down and let-bound, and may not be
returned, stored, pointed at or pushed into a container. A parameter of
type Fn is treated as one, which answers "passed to something that stores
it" with no interprocedural analysis -- the store is refused inside the
callee. Everything of type CFn is clean for free, which is the second
thing having two types buys. Every refusal names case 3, the environment
the collector owns.
Two pre-existing bugs fell out on the way. A lifted fn asked for Fnval,
so `flan reload' on any function containing an fn literal died at llc
with an undefined cell; it takes Flanfn now, which is the choice a
handler clause always made. And a redefinition module now carries its
own hidden copy of every thunk it names, which is the same bug shape
caught before it shipped.
The author edited (def colors [4 u32] [...]) in his running game, pressed
C-c C-c, and the colours did not change — the same complaint def was built
to answer, one step further in.
The reading behind it was that a re-evaluated def is a promise about the
next re-run, so the session republished the lifted global/<n> and stopped;
nothing called it. That is wrong for the reason the form is named after: def
is Common Lisp's defparameter, and evaluating a defparameter assigns. The
difference from defvar is not "one takes effect at restart", it is "one
takes effect, the other does not touch the value at all".
So a def now does both. The storage takes the new value at the next frame
boundary, carried by the thunk a redefinition module already has — one
Set per re-evaluated def, in the same flan_reload_call the class
registrations use, run after the bodies are published and on the game
thread. And the lifted initialiser is still republished, so the next re-run
runs the edited one; dev-rerun.flan pins that half unchanged.
A brand-new def gets its initialiser run too, which needed one thing from
each backend: a lifted global/<n> asked for by name is neither a sibling nor
one of the target's own lifted clauses, so it had no cell, and a dev call
goes through a cell. Both now give an unknown one a slot of the module's
own, filled from the registry by the installer.
An initialiser that signals leaves the old value alone — the value is
computed whole before it is stored — and offers abandon-evaluation like any
other thunk. A retype is refused first, by the pass that names both types.
defonce is untouched, which is its whole contract; defconst was already the
immediate one, through consts.
The first cut of the form-change refusal asked only about def and defonce
and asserted in its comment that defconst was another arm's business. It
was not: defconst to def at the same type fell past every arm, and defonce
to defconst fell past them into the consts republish, which stores the
declared value over live storage at the frame boundary. One refusal over
gconst and grerun together now covers all six directions.
And two coverage gaps closed by running rather than reasoning: reload-v6
carries a (def dial i64 5) the host was never built with, so the x86 image
path executes and its 5 shows in the transcript's arithmetic; dev-rerun's
echo reads counter in its initialiser and follows it 40, 41, 42, 43 across
re-runs, where a captured first answer would print 40 four times.
Three defects, all from lifting every def initialiser, none of which the
suite caught:
A def typed fresh into a live session came up zero and stayed zero. The
image flan_dev_global copies on the allocation is the only value a new
global ever gets — the host's .init-globals never calls its initialiser —
and both backends chose that image with Tast.const_init, which a def's
lifted Call fails by construction. Emit.initial_image reads the constant
back out of the lifted body; the x86 twin had the same bug.
Changing a global between def and defonce was silently ineffective: the
guard lives in the startup function compiled into the host, which a reload
cannot republish. Session.compatible refuses both directions and says to
restart; editing the value stays allowed.
And global/<n> no longer leaks into the signature refusal when a def is
retyped — the global loop names the same fact in words a reader can act on.
flan check prints def, defonce or defconst off grerun; (defvar) with no
arguments names the shapes rather than offering (defonce ); the docs,
plan.org, runtime comments and valgrind.supp are swept; BUILT.md states
the release-build cost and the uninit caveat.
The trio the author decided on 2026-09-20 is now all built: def is CL's
defparameter — its initialiser runs on every daemon re-run, unguarded, so
an edited initialiser repaints the same storage on C-c C-c plus re-run —
defonce (Clojure's name for CL's defvar, per the author) initialises once
behind the .init~once. flag, and defconst stays the image.
One parse arm reads both forms; the difference is Ast.reinit, carried to
Tast.global's grerun. Emit.startup_plan gives a def no guard flag, and
Check.check_global lifts every def initialiser — zero and literal
included — into global/<n>, so the host's startup reaches it through the
function cell and a re-evaluated def swaps it (Session's def_inits;
Emit.redefinition declares the cell for a non-sibling target). The old
defvar spelling is refused with the rename and both compiling spellings,
and every program, test, doc and editor list is swept — except sand.flan,
the author's live WIP, whose seven defvar lines are flagged in FIX.org
and keep its three dependent tests red on this branch.
The wait recognised one kind of stop and waited five seconds for all the
others, then said the program was not reaching a frame boundary — on a reply
that named the condition two fields along.
Which stop is the thunk's is decided by the agent's stop generation rather
than by the condition's name, so a break entered on the same class as the one
it was evaluated inside is still told apart from it. A (pause) is answered as
a (pause) wherever it came from, the flag having never been what made one
deliberate.
Five fixes off the independent review, plus the author's u8 ruling.
x86 parity: the bad-index block always ran x86 (it is flan dev's
default) and now says so with an explicit --x86; the condition render
gets an assertion under the x86 backend too, beside the LLVM one, and
a user error is pinned as carrying no site on both.
ArithError's layout is now pinned: {i32 op; i64 lhs, rhs} in C against
the prelude's defstruct, read field by field through the break loop's
render, driven from the editor through a divide under a restart-case.
That also covers condition and site on LLVM.
Three refusals that were wrong: trap_site tested the prefix "err"
and so ate any site whose path began with those letters; source_line
let Sys_error from input_line escape and take the whole break reply
with it, leaking the handle; and a condition with no fields was
reported as a name no struct has. The daemon now sends its own field
count and the buffer tells the two empties apart.
Nits taken: an over-long site is dropped rather than silently
truncated into a plausible one; the caret pads with the source line's
own tabs; the headline says when it has cut the field list;
flan-cnr-layout is live again as the single spelling of that request
rather than dead beside an inlined copy.
And the ruling: a u8 renders as 97 (\a) where a person is inspecting
and stays 97 where the program is printing.
The break loop used to discard the pointer it was handed, so the buffer
could name a BoundsError's fields and never show 648. Now the snapshot
stashes it, flan_agent_condition hands it back on the stopped thread,
and a daemon-built thunk — locals pointed at the condition — renders
each field. Delivered at-stop, so a resume-and-restop cannot get the
old type read over the new pointer.
The trap sites publish their loc around the hook call, the snapshot
copies it, and break answers :site with the line's text as :source —
the frame lines say where each call was; this is the only record of
the indexing itself.
Compiler temps are hidden from the locals listing rather than refused
as s4; a shadowing rebind strips its ~N except where the outer binding
is on the same list, where both keep their raw spelling.
Rebased onto dev-loop. Three conflicts were additive and both sides are
kept: FIX.org's two appended sections, want_map's diagnostics argument
against the class_sync inserted beside it, and test_dev.ml's agent-socket
block against this lane's migration block, whose comment no longer says
"the block above" now that something sits between.
The fourth is the one the auto-merge hid. flan_dyn_class_def's argument
check was written against the pre-diagnostics trap1 and merged clean into
a tree where trap1 takes a location first, so the class name would have
been read as a length. dune build does not compile flan_dyn.c, so the
green build said nothing; caught by compiling a program.
Two pins in test_session.ml asserted "flan_dyn_class_def" against the IR
text, which every module contains because emit.ml declares every runtime
entry point in all of them. Both now assert the call and the packed slot
list. Checked by mutation: with the thunk suppressed the old needles pass
and the new ones fail, along with the daemon's slot count.
Also disclosed: say_render is the second raw reader beside render, and
neither syncs, so a stale instance shows its old slots in the inspector
until something touches it. That is the editor-facing consequence of
keeping the printers printers, and it is now in the runtime comment and in
FIX.org rather than left to be met. And the stale-caller walk says in as
many words that it is a tripwire, unreachable on purpose, not a filter to
be tidied away.
CLHS 4.3.6's update protocol, minus the user hook, on the dyn side's
defclass. Redefining a class used to be silent: a class is sugar for a
constructor defn, so the edit replaced a body and the instances already in
the program kept their old keys for ever.
Three pieces. A registry in flan_dyn.c holding each class's current slot
list and a generation, made only of interned kw_entry pointers so the
collector has nothing to trace in it and no root to push for it. A uint32
generation on the instance, fitted into the padding kind and mark leave in
front of len's alignment — sizeof(flan_obj) is 48 with it and was 48
without, and flan_dyn_obj_size is there so a later field that moves it
fails a test. And a registration thunk per reload, run by the agent
through flan_reload_call after the module's bodies are published: it has
to be a thunk, because the case this exists for is a class redefined and
not constructed.
Migration is lazy, at want_map, len's map arm and dyn_equal's. Slots kept
by name, gained slots nil, dropped slots gone, identity preserved, entries
rebuilt in the class's order so a migrated instance is indistinguishable
from a fresh one. Equality migrates both operands first, so it is over the
class as it is now.
The session had to stop refusing the constructor's signature change, and
does so only for a defclass and only when no compiled caller is left
behind. The checker gets there first in practice; the walk in eval holds
the reason locally rather than inheriting it.
The registry is advisory: a class instance is an open map, so a key a raw
put wrote that the class never declared is dropped by the next migration.
FIX.org says that plainly rather than pretending enforcement.
A defclass is a named dyn map with a shape tag, and a generic function
dispatches on it two ways: CLOS's, where the dispatch value is the class
of the first argument, and Clojure's, where a body computes it. They are
one mechanism and not two — a class dispatcher is (class-of arg0) as the
dispatch function, which is what lets a method written for the class
point and one written for the value :point be the same branch.
(defclass point [x y])
(point 3 4) ; the constructor, positional
(class-of p) ; :point, or nil for anything else
(defgeneric area [self] dyn)
(defmethod area point [p] (* (get p :x) (get p :y)))
(defmulti describe [x] dyn (get x :kind))
(defmethod describe :square [s] ...)
(defmethod describe :else [s] ...)
A slot is a key in the instance's own map, so get, put and has-key? are
how one is read and written and no operation was added for any of it.
What the class adds is the tag, and the tag lives in the object's header
rather than in a reserved entry — the queue's note said a reserved key
and this departs from it, because a key would be counted by len, walked
by the renderer and compared by equality, so every instance would answer
a length one larger than its slot count and print a key nobody wrote. A
header field cannot be reached by get or put at all, so no user key can
collide with it. It costs nothing: the map arm of flan_obj's union grows
to the size the view arm already had, and sizeof(flan_obj) is unchanged.
It needs no tracing either — the tag is an interned keyword entry, which
is immortal and is not a collector object.
The tag shows up in exactly three places: class-of answers it, equality
compares it (two instances of one class compare by their slots; an
instance and a plain map with the same entries do not, which is
Clojure's answer for a record beside a map), and both renderers print it
— #point{ :x 1 :y 2}, Clojure's own spelling.
None of the four forms reaches the checker. lib/classes.ml turns the
whole declaration list into ordinary defns at the top of build_program,
the way Shim.expand already turns a declare-c into a declare plus a
defn: a class becomes its constructor, a generic becomes one function
whose body binds the dispatch value and compares it down a chain, and a
method becomes a branch of that chain. It is a pass and not a macro
because a macro sees one form and the generic's body is not decidable
until every method is in hand — a method may be written above its
generic, below it, or arrive at a reload an hour later.
That last case is why the method bodies are inlined rather than lifted.
A generic is exactly one top-level name, so adding a method to a running
program is the ordinary redefinition of one function, through the cell
every call site already goes through. session.ml names the generic
alongside the method's own declaration name for that reason. The cost,
recorded rather than hidden: a method is not separately callable and is
not a frame of its own.
A dispatch that finds no method signals NoMethod, a prelude struct
carrying the generic's name and the dispatch value that missed. A
condition and not a trap, because a miss is something a program can be
written to answer, and handler-case around the call is the shape. Its
value field is dyn, the first condition here with one; the per-type
descriptor an item-2 struct carries is what the collector reaches it by.
No restart is established at the miss, which is BoundsError's decision
taken for BoundsError's reason.
Both backends, identically: the two new runtime entry points are
declared in emit.ml and the x86 backend needs nothing, since a dyn call
is a dyn call there. Deferred and written down in FIX.org: inheritance,
multi-argument dispatch, :before/:after/:around, named-slot
construction, unknown-slot checking, and computed dispatch values.
