Emacs binds it in emacs-lisp-mode-map and nowhere else, so a mode derived
from lisp-mode inherits nothing and the key answers "undefined" — which
reads as the client being broken rather than as the key being free.
`-dev-` was in every Emacs symbol this client owns and meant nothing to anyone
typing one: the daemon is `flan dev` at a shell, but from inside Emacs there is
no other kind of connection to distinguish it from. `M-x flan-dev` is now
`M-x flan`, `flan-dev-quit` is `flan-quit`, the private prefix `flan-dev--` is
`flan--`, and every defcustom follows — ninety-odd symbols, with the two files
renamed to emacs/flan.el and emacs/test-flan.el so the file names say the same
thing as the symbols in them.
No aliases. Renaming a defcustom breaks a config that names it and there is no
way around that; the repo has no precedent for softening one, and an alias left
behind is what keeps a rename from finishing. MANUAL.md says the old names are
gone and how to fix a config, which is the whole of the migration path.
Three strings are not symbols and keep their spelling: `.flan-dev.sock`, which
bin/main.ml writes and which a renamed variable searching for a renamed file
would simply never find; and the two buffer names `*flan-dev*` and ` *flan-dev*`,
which name the `flan dev` subcommand's own output rather than anything in elisp.
`flan dev` with a space is the CLI and is untouched everywhere.
The entry point also stops asking a question it already has the answer to. From
a buffer visiting a .flan file it starts that file; from anywhere else it reads
one from the minibuffer as before; `C-u` reads one either way, which is how you
start a second program without leaving the first. The current buffer is still
the only source of the default — the bug where a previous project won over the
buffer you were in was fixed by removing `flan--file` from that position, and
nothing here puts it back.
Four checks on the `interactive' form, evaluated on its own rather than by
calling the command, because calling it would build and launch a program and
the question is only which file the form arrives at and whether it had to ask.
A fifth asserts that nothing answers to the old names. test/test_emacs.ml loads
the test file by path and test/test_session.ml names the client file in a
comment, so the rename reaches those two lines; nothing else outside emacs/ and
the docs moved. Verified by byte-compiling every file
clean and by `dune test` and `@page`.
The 30s deadline in the reply reader was a literal and its message said only
that nothing had arrived. It is flan-dev-reply-timeout now, and the message
names the daemon buffer to look in -- a first compile on a cold cache is the
case that legitimately runs long, and the build log is what says so -- and the
setting to raise. Still never resent: a request the daemon took and died on
may already have run.
Package headers on all eight client files, so package-install-file on the
directory works and the client is not reachable only by load-path. The
daemon-buffer defcustom moves up beside the other buffer names, because the
reply reader now names it and the byte-compiler reads a file in order.
The name freed up by the rename now means what C means by it: the members
overlay one storage, the size is the largest of them, the alignment the
strictest, and nothing anywhere records which one was written. It serves
two things that wanted it. Binding a C header means holding the union the
library holds and reading whichever member the library's own tag says is
live -- a tag Flan cannot see, because the rule relating them is prose in
a manual. Overlaying an f32 on a u32 to look at its bits is the other,
and it is the same read.
So that read is defined rather than refused. This is the one place in the
checker where bytes win over safety on purpose, and the alternative was
not a safer language, it was no feature: type punning *is* reading the
member that was not written. The promise is the one C's implementations
make and C's standard does not -- the layout is the target's, the bytes
are the bytes, a read is a reinterpretation of them -- and what is not
promised is anything about bytes nobody wrote, where a member wider than
the one last stored reads a tail that is indeterminate exactly as a
struct's padding is. ZII narrows that to almost nothing: a union starts
all-bytes-zero unless uninit says otherwise.
uninit on one is allowed, unlike on a defdata. The refusal there was
never about garbage; it is that a tag steers, and a tag no case names
falls past every comparison in a match into a block LLVM may treat as
unreachable. An untagged union steers nothing.
Which is also why three things are refused, each for a reason that does
not expire with a milestone. No move-only member: nothing knows which
member is live, so nothing can tear one down, and unlike the struct and
defdata refusals this is not waiting on recursive teardown -- there is no
fact for teardown to read. No bool at any depth: an i1 loaded from a byte
that is neither 0 nor 1 is a value the optimiser may assume cannot exist,
and a union is the only type that can produce one. No defdata at any
depth, for the reason uninit gives, arriving the other way round. An
Option member is fine and the walk says why: its match is a tag test and
a branch, not a chain with an unreachable tail.
Two members in one literal, a match on a union, a union map key and a
member written into a global initialiser are each refused by name.
A union is a field list whose every offset is zero, so it travels as a
Tast.structure and the checker, the emitter and the x86 backend each grow
one table rather than one shape. A value is a zeroed temporary and a
store -- Set over Pfield, which every backend already has -- so there is
no new IR node and no layout rule spelled out a second time per backend.
The LLVM type is the blob clang gives a union, the DWARF is
DW_TAG_union_type with every member at zero, and the printer names the
type and does not walk it: it cannot know which member is live, and one
of them may be a pointer.
cimport can now check what it could not. A C record holding a union
member was not recorded at all, so the defstruct beside it went unchecked
rather than checked wrongly; a named union member resolves to a defunion
now and the whole record is compared field by field. The defunion itself
is compared against the header's union as a set and not in order --
every member is at offset zero, so a permuted one is the same type and
reporting it would be a finding that is not one -- while a member the
header has and Flan lacks is reported, because that is what changes the
size. A defunion against a C struct, or a defstruct against a C union,
is reported in both directions. An anonymous union member is still
skipped, and the comment now says that the gap is on the Flan side:
there is nothing to declare.
Flan's tagged sum has been spelled defunion since it landed, which was
accurate right up until the language wanted C's untagged union as well.
Both cannot be called the same thing, and the tagged one is the one with
an alternative name that says what it is: a case, its fields, and a tag
that steers which case is live is a data type, not a union.
So the form is defdata everywhere -- the parser, the AST, the checker,
both backends, the prelude's Form, the editor's font-locking and imenu,
the docs and every .flan file in the tree. The internal vocabulary moves
with it: Tast.union is Tast.data, uname is dname, the tables the checker
and the emitter keep are datas. Leaving them would have inverted the
words permanently, with surface defunion meaning one thing and
env.unions meaning the other, which is exactly the kind of drift the
comments in those files exist to prevent. What did not move is case,
variant and vfields: a tagged sum still has cases, and it still has one
live at a time.
defunion is not kept as an alias. An alias would compile the day the
untagged form lands and mean the opposite of what it used to -- the same
silent misparse that made defn's return type mandatory, and worse,
because the reader would have no reason to look. The old spelling is a
named refusal instead, parse/defunion-renamed, which says what it is now
called and that the name is reserved for something else. It fires on the
head alone, so (defunion U [A B]) -- which would otherwise have parsed
cleanly as one field A of type B -- is refused with the rest.
basis had the same false promise the eval note did. It branches on the break
state, which answers "running" while the program is parked — the agent's
listener is alive and nothing has stopped — so disassemble reported that a body
delivered while parked installs at the next frame boundary, which is not a
boundary the program will reach until somebody runs it again.
And flan-rerun had no autoload. The keymap binds it, and flan-mode.el says in
as many words why every command there needs a real autoload rather than a
declare-function: a user who loaded only flan-mode would otherwise find the key
bound to nothing at the exact moment they most want it.
You run a program under flan dev, it opens a raylib window, you close the
window, main returns — and there is no way to get another window short of
flan-dev-restart-program, which throws away the build, the session and every
global with it. In Common Lisp or Clojure the image outlives main, so you call
it again. The process here already outlived main: the exit hook flushed, closed
stdout and sat in for (;;) pause(). Nothing could wake it.
So main() is a loop. The hook records the status and longjmps back into a
setjmp in main() — there is no return available, since flan_exit is reached
from wherever the program happened to be — and the thread waits on a condition
variable until the new rerun op signals it. The main thread is the one that
runs main again: a window belongs to the thread that opened it, and on macOS to
the first thread of the process. A longjmp pops no frame, so the park first
empties the handler stack, the restart stack and the shadow frame chain, each
of which was a chain of allocas in stack the next run is about to write over.
Nothing else is reset; the second run reads whatever the first left in the
globals, which is the semantics that was asked for.
Closing stdout had to go with it. That was how the compiler learned the program
was done, but a pipe delivers EOF once, so the signal and the program's output
were the same resource and spending it left the second run with nowhere to
print. The descriptor hazard the old code reopened /dev/null for goes away with
the close that caused it. Liveness is asked for instead, through a weak symbol
in the same style as the agent's, and is now three states rather than two: Live,
Parked and Gone. Every guard branches on that before consulting the break
state, because the agent's listener answers "running" while the program is
parked and telling somebody whose program has finished that it is running is
worse than saying nothing. Only eval accepts a parked program — it queues and
waits for nothing, and the queued module installs at the first frame boundary
of the next run, so a body can be fixed while parked and the re-run executes
it. Everything else needs a frame boundary or a stopped stack, has neither, and
says which, naming the command that gets the program back.
A re-run while the program is running is refused rather than queued: the test
and the signal happen under one mutex, so two mains writing the same globals at
once never starts.
:parked rides on every reply beside :stopped, for the reason :stopped does —
finishing is as unannounced as stopping, more so when the way it happens is a
mouse click on a title bar. Emacs shows flan:parked in the modeline and binds
flan-rerun to C-c C-M-x.
C-c C-m. One step on the bare key, the fixpoint under C-u: a macro may
quasiquote a call to another macro, and Loc.from_macro is outermost-wins, so
by the time a full expansion settles the intermediate name is gone. One step
is the only thing that can say which macro produced what.
The expansion runs against the macros the *session* holds -- the prelude's,
its imports', and every defmacro evaluated since it started -- and writes
nothing back: a defmacro handed to C-c C-m does not join the session by having
been looked at.
Both non-termination refusals stay refusals, and only where they are needed.
One step makes one call and does not look at the answer, so (s/spin) one-
stepped answers with itself; all the way hits the fuel and names the macro,
inside Dev.serve's guard, so the daemon replies rather than hanging. Macro's
module handling is a Fun.protect now -- a build that raised was a process
about to exit, and the daemon is not that process.
No printer for a Form existed. Form.to_string is an error-message renderer and
is what Macro.key digests, so it is untouched; Form.to_source round-trips
floats, strings and bytes through the reader, and Form.pretty decides where
the line breaks go and leaves the columns to flan-mode.
The answer is a read-only flan-mode buffer shaped like the disassembly one,
with cnr's idea in it: m expands the form at point one more step in place.
Three inherited keys refuse by name -- an expansion is in no file. The text is
sent padded onto its own line and its own column, unlike C-x C-e, so the
refusal lands on the call and not at the start of its line.
render.ml's output and emacs/flan-inspect.el's parser are the two ends of one
wire format, which is why the printer was left on the colon when the rest of
the corpus moved: shifting it alone would have broken inspection in the dev
loop without breaking a test that said so. They move together here.
The field list in the inspector is labelled with the dot too, which is the
spelling flan-inspect-step-expr already used to build `(.x b)' — the label and
the expression it stands for now read the same.
One case needed a guard the colon never did: `...' also begins with a dot and
is the renderer saying it stopped, not a field called `..'. A field name never
starts with a second dot, so one character of lookahead separates them.
The colon is not gone from the rendered grammar. An enum member is `:green' and
is a *value*, so the two are now told apart by the character alone, which is
the only thing that distinguishes them.
Also font lock, handed over with the same change: `:name' was the rule that
drew field labels, and with the colon belonging to keywords every label in the
corpus was left unfontified. `.name' is drawn as a constant, in both the places
it appears — the label in `{.x 1.0}' and the accessor in `(.x v)', which are
the same name.
The reported bug — the second and later bindings of a let one column too far —
was never one missing rule. `flan-indent-function' checked the head of the
enclosing form, and inside a binding vector the enclosing open is `[' and the
symbol after it is the first binding's name, so it fell through to Emacs's
`lisp-indent-function', which treats the vector as a call and aligns under the
first argument instead of the first binding.
Emacs Lisp is the wrong reference. It has no vectors-as-bindings, no maps and
no bracket variety, so every rule Flan needs has to be added by hand and the
binding vector is simply the first one hit. The indenter is rewritten from
clojure-mode's source instead: `clojure-mode' is neither an ancestor nor a
dependency — flan-mode still needs nothing beyond stock Emacs — it is the file
whose rules were read and written out again.
A bracket aligns under its first element, and that one rule fixes the binding
vector, `defn' parameter lists, `restart-case' and `handler-bind' clause
parameters and both spellings of a struct literal at once. `{:x 1}' and
`{.x 1}' indent identically because nothing here looks at the key, which is
what the colon-to-dot lane needs of it.
Where Flan diverges it is handled on purpose. `defn' is `:defn' rather than a
count because the return type between the parameters and the body is optional.
A clause — `(Name [params] body)' — is recognised by its shape, since its head
is a condition class or a restart name and can never be in a table; clojure-mode
reaches the same clauses by backtracking out to the enclosing form, which buys
generality this language has no other use for. Special arguments indent by one
body rather than Clojure's two, and a call whose head is alone on its line
indents its arguments by a body rather than aligning them under the head,
because that is how the whole corpus is written.
Checked by reindenting every .flan file in the tree: the only lines that move
are sand.flan's reported bug, raylib.flan's hand-wrapped parameter vectors —
which is the fix — and lone-`;' comment continuations, which stock
`lisp-indent-line' has always moved.
test-flan-mode.el is loaded from test-flan-cider.el rather than given a stanza
of its own, because emacs/*.el is already a dependency of that test.
Two failures in test-flan-cider.el that predate this: fixture frames lacked
`:fetched', so folding one open went looking for a daemon, and `layout' was
identified by being the last request when `flan-cnr-show' now makes three.
session.ml already had this: a compile-time walk over a Tast type that
emits the calls to print a value of it, handling every concrete type the
language has. It was dev-build-only and went to flan_dev_emit, and
prelude.ml justified the per-type print-* functions by saying a real
println had to wait for milestone 5 and generics. It did not. plan.org
specifies println as compiler-provided and per concrete type, which is
not overloading: there is nothing to dispatch on at run time and no
user-supplied printer to choose between, so no type variables appear.
The walk moves to render.ml, parameterised on an emitter and a slot
allocator. The emitter is five functions rather than five extern names
because the two sides are not both extern calls -- the REPL's are, and
stdout's compose a conversion with a write. The slot allocator differs
too: the REPL builds a thunk's frame, println takes slots from the
enclosing function being checked, once per call site.
Two runtime shims, both only reachable from the walk. flan_u64_to_bytes,
because routing u64 through the signed printer makes 0xFFFF...F read as
-1, which is the one way println could disagree with the REPL about a
value both can hold. flan_escape_bytes, so a string nested in a printed
structure is quoted and escaped -- same table as flan_dev_emit_str, noted
in both, because the REPL and println must not disagree about what a
struct looks like.
A string at top level prints raw and nested prints quoted. Not a conflict:
(println "hello") has to print hello, and a struct's string field has to
be distinguishable from the punctuation around it. The split is top-level
vs nested, so it lives in check.ml and not in the walk.
Found on the way: a field of an Option had no gep in emit.ml, so the
walk's Option arm had never run -- the REPL would have failed on one too.
Option is { i8, T } with no declared name, so its layout is now spelled
out. Nothing in the surface language reaches a field of an Option; the
printer does, to read the tag without unwrapping a None.
The print-* functions stay. They print without a newline, which println
cannot express -- slices.flan's show prints elements separated by spaces
-- and they are raw where print is structural.
println.flan covers every arm at -O0 and -O2: the u64, the raw/quoted
split, both Option arms, the depth and span caps, and the slice arm's
loop twice over plus once inside a dotimes, which is where per-call-site
slot allocation would show if it were per-iteration.
Two CIDER-shaped buffers: C-c C-i navigates a value, C-c C-b shows the
condition, the restarts and the stack. C-c C-M-b keeps the old one-key prompt.
The inspector needs no protocol change at all. eval-expr already answers a
rendered string, and Session.render writes exactly seven shapes, so that string
is a grammar. Navigation is a stack of *expressions* rather than of handles:
going into :pos sends (.pos b), into element 2 sends (at (.tags b) 2) - both
ordinary Flan a person could type. CIDER keeps its stack on the server because
a JVM value can be retained; nothing here can, since a Flan value has no header
and the render thunk is dlclosed the moment it returns. The view is therefore
never stale, where CIDER's shows the object as it was when you pushed. What it
buys over C-x C-e is the depth-4 span-8 bound: a field past it comes back as
... and nothing recovers it from the echo area, and re-rooting renders it from
depth 0.
SBCL decided the order - condition, restarts, then stack - because invoke-debugger
prints the condition and show-restarts and then stops; the backtrace is a command
you type. The restarts are the decision and the stack is the explanation for it.
And SBCL found a live bug. show-restarts omits the bracket on a name already
used further in, which is not decoration: §4 takes the first frame offering a
name, so a second frame offering retry is real, is on the list, and cannot be
chosen. The old prompt showed retry twice and sent the string either way, and
the inner frame took it silently. restarts.flan's own nested function has been
that counterexample since the transfer landed. The buffer draws the shadowed row
unbracketed and refuses RET on it by name, with a test asserting nothing was
sent - which stops the lie without restoring the choice. Taking a restart by
index is the fix and is recorded as such.
Sections that cannot be filled are drawn saying why rather than omitted: a
missing section cannot be told from an empty one, and only one of those is a
fact about the program.
C-c C-a on a name, C-u for the IR. The header is SBCL's habit of saying
which function and out of what before a line of code, with one line it does
not have: what the answer claims. A reader looking at a listing will assume
it is what the program is running, and for a delivered-but-not-yet-installed
body that is exactly the thing that is not known — so the daemon's own
account of it sits above the first instruction rather than nowhere.
NEXT.md rewrapped to a wider column - a reflow, not a rewrite. The three TODO
entries in it are the substance: live disassembly of what is actually installed
in a cell, error overlays that vanish on the next thing you do rather than
surviving until an evaluation is accepted, and CL-style interactive recovery
where a stopped program offers a typed restart and the editor asks for the
value before invoking it.
flan-mode's declare-functions become real autoloads. A declare-function only
quiets the byte compiler; it does not load anything, so a user who had loaded
only flan-mode could not invoke M-x flan-dev at all.
A program that does not compile kills the daemon before it binds, which is
the failure anyone starting one from Emacs will actually hit. Showing that
buffer is the difference between a message and an answer.
The prompt also offers the program last started: a restart after a quit is
the common case, and it is rarely the buffer you happen to be reading when
you decide on it. C-c C-x does the restart without the prompt at all.
A struct whose layout moved cannot be installed into a program built with the
old one, and the daemon says so. There is no smaller answer than a rebuild: a
session's layouts and global types describe a process only if that session
compiled it, so the program and everything in its memory go too. That is the
cost, and it is why this is its own command and not something C-c C-c falls
back to.
Emacs owns the daemon now, so this is stop-and-start rather than a new op.
The old one is waited out first: it unlinks the socket as it leaves and would
otherwise take its successor's with it.
Also: quitting a daemon that would not close now says its program may have
outlived it, because killing the daemon skips the cleanup that signals the
child — and C-c C-v rather than C-c C-h for the doc buffer, which was
shadowing the way anyone discovers what is under C-c.
C-c C-h puts what the daemon knows about a name in a buffer instead: kind,
signature, and a button on the place it is written. No new protocol — defs
has carried all four facts since it existed.
Where there is no location it says so in M-.'s own words rather than leaving
the line out, because a missing line reads as "this name has no home" and
the truth is that Tast.global carries no Loc.
imenu and which-function come with it, and neither needs a program running:
they read the buffer, so they work on a file nobody has built yet and keep
working while it is stopped. Anchored at column 0, so a defn inside a let is
not offered as a definition of anything.
The break loop was reachable from a raw socket. This is the half that makes
it reachable from an editor, and it all follows from one fact: a program
stops at a moment nobody asked about.
So the state is learned twice, on purpose. It rides on every reply, beside
the program's output and for the same reason -- the likeliest instant for a
program to stop is the one just after an evaluation, which is a reply the
client is already reading, and learning it a second later from a poll would
mean learning it after the echo area had said the evaluation was fine. And a
timer asks anyway, once a second with `describe', because a program that
stops in a frame of its own game loop produces no reply at all and folding
state into replies that never come says nothing. The timer never reconnects
-- that would quietly erase the `lost' state that exists to be seen -- and
skips while a request is in flight, since accept-process-output runs timers
and a poll firing inside a read would eat that read's reply.
Three ops: `break' for the restart names, `restart' and `abort'. The
annotation owns :stopped and :condition rather than the ops, so one place in
the daemon decides whether the program is stopped and the poll and the prompt
cannot disagree. "ok" from `restart' means accepted, not resumed: the choice
is validated against the stopped stack and taken when that thread next comes
round, so it says so and the client clears its own flag rather than polling
once, finding it stopped, and re-opening the prompt it just answered.
The agent grew one verb, `status', answered in both states. Everything else
the break loop offers is refused while running, rightly; but the question an
editor asks without already knowing had to have an answer either way or there
would be nothing to poll.
And flan_agent_poll had to become re-entrant, which was a bug rather than an
addition. A C-x C-e thunk may itself error, and the break loop that catches
it polls again from inside that call. The old loop cached both indices and
stored tail at the end, rewinding over everything the nested poll consumed --
re-running the thunk that had just stopped the program, which is an unbounded
recursion of breaks. Each job is now claimed before it is run. test_dev.ml
evaluates an expression that errors and resumes it, which fails against the
old shape.
flan-repl.el is a comint buffer whose every line goes through the same
eval-expr request C-x C-e uses - no new protocol, no compiler support. Deriving
from comint rather than hand-rolling a prompt is the same call as deriving
flan-mode from lisp-mode: history, the input ring and kill/yank already exist
and are not worth rewriting. There is no subprocess behind it; the "process" is
a stub comint needs in order to have a prompt.
It is program-scoped: a name typed at the prompt resolves against the running
program's top-level namespace, so in sand you write sim/settle. A buffer
visiting a package's file gets the alias applied for it because the file says
which package it belongs to, and a prompt has no file to derive one from. RET
on a half-typed form opens a line instead of sending it, with balance checked
through the Flan syntax table so a paren inside a string does not count.
A value and the program's output are different things and arrive by different
routes: the value is the result of the request and appears at the prompt, while
anything printed rides along on the same reply into *flan-output*. Showing them
in one place would be convenient and wrong, so there is a test for the
separation - and it caught a real bug. The renderer's Unit case emitted () with
no evaluation at all, so (print-line "x"), the most ordinary thing anyone types
at a prompt, answered while nothing happened. A Unit expression is almost
always a call made for its effect; it is evaluated and then reported.
Its stdout is a pipe into the daemon now, and whatever it printed since the
last reply rides along with the next one into *flan-output*. Arriving with a
reply rather than by a separate request is the point: the output an evaluation
itself caused is the output anyone wants to see.
Draining that pipe is a liveness requirement, not a nicety. A pipe nobody reads
fills at 64K and the next write blocks the program forever, so it is read from
the accept loop's select whether or not an editor is asking, and the buffer is
capped - a program printing every frame must not grow the daemon without limit,
and the newest text is the useful end.
test_dev read the program's transcript off the daemon's stdout, which is no
longer where it goes; it collects :output from replies instead, which is also
what the editor does. The emacs test moved to a fixture that keeps running,
since it now evaluates more times than the old one had reloads to give.
A different primitive from redefining a name. There is no name to install a
body into, so the expression is wrapped in a function with nowhere to be called
from; the module exports flan_reload_call to say "run this once", and the agent
calls it after the install - on the game thread, at a frame boundary, so an
expression that reads the program's state sees a point the program agrees is
consistent.
Nothing is marshalled back because nothing could be. A Flan value carries no
header, so no code at run time can say what it is; the compiler knows the type
and renders it there, in the thunk. That is the layout decision's bill, and it
is why the printer set is the scalars rather than everything.
The rendering does not go through stdout. Stdout belongs to the program, it is
in the hot path for anything that prints, and a dev-only feature must not put a
branch in it - so flan_rt.c is untouched and the value goes to flan_dev_result,
read back over the agent's socket. Safe without a handshake because the
generation counter is bumped last: the daemon waits for it to move rather than
assuming the program has reached a frame boundary.
u64 refuses by name, because i64->bytes is signed and anything past 2^63 would
come back negative. Everything without a derived printer refuses the same way.
A number that is quietly wrong is the failure this whole thing exists to
prevent.
An evaluation is not a declaration: the thunk is built against the program and
never spliced into it, so describe does not fill up with an eval/N for every
expression ever typed.
The test that matters is the same expression twice. The fixture increments
ticks every frame, so two evaluations must disagree - a value computed in the
compiler, or read from a copy of the program's state, would not.
C-c C-c recompiles the top-level form at point and installs it in a running
program at that program's next frame boundary. Verified against sand: an
unsaved buffer edit to game-draw, and 240 consecutive frames drew it.
flan-mode.el derives from prog-mode with lisp-mode's syntax table, which is
most of the work - Flan is s-expressions, so sexp motion, paren matching,
beginning-of-defun and indentation are already right. What it adds is Flan's
own brackets ([ and { are brackets and not symbol characters, since every
binding list and every type is written with them), the characters a name may
contain, and its keywords.
flan-dev.el has no parser in it, which is what the protocol choice bought:
prin1 writes a request, read reads a reply. C-c C-k sends a buffer as one
module rather than a form at a time, because a defvar and the function using it
have to arrive in the same load or the first refers to storage that does not
exist yet. An error comes back with a location and point moves there.
Framing is in bytes and Emacs counts characters, so every length goes through
string-bytes and the process is binary. Otherwise one non-ASCII character in a
buffer puts the reply stream out of step by exactly as many bytes as the
payload has of them - a bug that reads as a corrupt protocol and only appears
for some people. test_emacs.ml drives the real client against a real daemon for
that reason: it is not the same claim as the daemon answering correctly, and a
mistake in the framing, in beginning-of-defun over Flan's syntax table, or in
the reply reader passes test_dev.ml and fails here.
