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superseded rather than built, and macro-expansion source locations are on an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.
Three from a review of the commit before this one, and the first is a dev
loop defect. Naming the widening thunk thick/<count so far> put traversal
order into a symbol, and Session.compatible compares a reload's functions
against the running program's by name -- so swapping two calls in a body
renamed nothing the programmer can see and reported "thick/0 changes
signature, from [i32] i32 to [i64] i64. Restart to change it." The name is
the signature again, written by thick_enc: every type self-delimiting, an
atom as its length and then its spelling, so the boundaries mangle_ty loses
are in the string rather than inferred from the separators. mangle_ty is
untouched -- it is load-bearing for the instantiation names a backtrace, a
Reach edge and a dev cell show -- and the memo stays keyed on the types.
fn-thunk-reload.flan is the pair of widenings and test_session reorders them.
The second was a silent miscompile. bind_ty's Fn-pattern-against-CFn-argument
arm was structural, so it matched nested function positions too, and the
catch-up pass that builds the thunk compares the whole substituted parameter
list -- false when the mismatch is inside one, and the fallthrough handed the
argument over unchanged: one word where the instance declares two, 255 on
both backends with nothing said anywhere. The widening is a value the caller
builds around the whole argument and there is nowhere inside one to build it,
so the arm is admitted at the top of an argument's type and nowhere else, and
the catch-up arm is total over the pair rather than guarded -- bind_ty's
fallthrough is Types.fits, which admits Never, so a binding can still succeed
over a pair the two words cannot bridge. fn-generic-nested.flan is the
parameter position and fn-generic-nested-return.flan the return one.
And the third closes the hole the escaping inversion was for. A match arm
binds the case's fields to slots and the store that fills them is inside the
branch, not in any form escape_check reads as a binding, so (match o (Some f)
f ...) handed back through a name what a case-field read cannot hand back at
all -- sound only because Some_ denies suspects. An arm's slots of function
type are suspect now, for the same reason the read itself is.
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: "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.
rand-int, rand, rand-bool, rand-int-range and rand-float-range, at the widths
the author ruled: a u64 draw and an f64 in [0, 1). rand-seed and rand-state
keep their names. The four old names are not names, and each is refused by the
one that is, with a call that compiles — in both the call and the bare-name
position, because a Lisp-1 makes the second a real thing to write.
The generator's step is untouched, so a seed means what it meant. Its output
function is not: PCG-XSH-RR folded the state to 32 bits, and no honest u64 or
53-bit f64 comes out of 32 bits without a second step. PCG-RXS-M-XS 64 answers
64 from the same one, so all five still cost exactly one draw and a seeded run
is reproducible. The price, written where it lives: the permutation is a
bijection of the state, which is what 64 output bits from 64 state bits costs.
The sequence is therefore a different one, and programs/rand.flan pins it —
reproducibility across the five, the single-draw cost of each, the half-open
boundaries, and rand-bool's count over a thousand flips.
sand.flan is not touched. It calls rand-f32, so the cases that compile or
re-evaluate it skip themselves on the fixture rather than on a comment: fix
its two calls and every one of them runs again. Its hash is the old
generator's grid and gets re-taken then.
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.
