Joseph Ferano
e3565b30e8
Every mark it left was an addition, and addition commutes, so a backend that ran the defers outermost-first produced byte-identical output and the row that was supposed to be watching the order could not have told. The claim was in the comments and not in the numbers. cleanup.flan already had the device for this — a shift rather than a sum — so the log here is a digit trace now, and the two frames under a catch read 12 where a wrong order reads 21. Rewriting the trace made room for the three behaviours that worked and nothing pinned. A return inside a clause is an ordinary return from the function that wrote the form, because that is where a clause runs: it leaves through the function's own exit, runs the defer registered there after the two the unwind already ran, and leaves the handler stack empty behind it, which the bare signal that follows in main is the check on. A defer inside a clause is refused for the reason every nested form is refused one. And a handler-case inside a defer works, because a defer may not start a transfer that leaves it and this one begins and ends its own. The program is registered with the sanitizers, where the interesting failure is not the heap but a handler or restart frame left on a stack pointing into an alloca that has gone — an output comparison cannot see that until something much later calls through it. It is clean; it was also leaking sixteen bytes out of the vector main allocates to prove the allocator context came back, which is the test's own litter and is freed now. docs/PORTING.md ranked handler-case as one site handler-bind covers. It still is one site, and handler-bind still covers it, but it is no longer the closer translation: a catch block is assumed everywhere it is written to see the locals around it, and only the clause that runs at the form does. The handler clauses are lifted left to right rather than by List.map, whose order is unspecified. Each lift names itself after the count already on the list, so an order nobody chose would number the clauses of one handler-bind differently between builds, and those names go into a redefinition module.
What is in here, and what is still true
These are the documents that are written once and read occasionally: the reasons behind the code, the
reports from finished investigations, and the record of individual work sessions. The documents that are
edited every day stay at the repository root, because source comments cite them by bare filename from
dozens of places and a path that moves is a path that rots. So plan.org, NEXT.md, spec-memory.md
and spec-conditions.md are one directory up, and everything here points back at them.
A note on how to read the citations below: a document in this directory that says plan.org means the
one at the repository root. Nothing in docs/ is named for a file at the root, so there is no ambiguity,
and rewriting a hundred prose mentions into ../plan.org would have cost more in readability than it
bought in precision.
If you have thirty seconds
Read BUILT.md. It is by far the largest document here and it is the one that pays: it holds the
reason behind every part of the compiler that exists, from why nothing is ever dlclosed to why the
printer is a compile-time walk over a type rather than a runtime function. It is current, it is
maintained, and deleting it would mean deriving all of it again. If you want to know why a thing is the
shape it is, the answer is in here.
After that, ../NEXT.md at the root for what is actually in flight, and REFERENCES.md here for
where the evidence comes from — the reference clones on this machine, what each one answers, and the
standing rule that a claim in these notes was read out of a clone rather than recalled.
The current documents
| File | What it is |
|---|---|
BUILT.md |
Why the parts that exist are shaped the way they are. The longest and the most load-bearing document in the repository. Current. |
DISCUSS.md |
Open questions, raised and deliberately not answered. Nothing in it is a decision or a task; entries that have since been answered say so and point at where the answer landed. Current, though it is half archive by now. |
PORTING.md |
What the author's game, siam-farmer, needs from Flan that Flan does not have yet, measured against the code that exists rather than against a plan. It is the requirements document the language is actually steering by. Current. |
REFERENCES.md |
The reference clones under ~/Repositories, what each one is consulted for, and the specific files and lines already cited from them. Current. |
The reports
| File | What it is |
|---|---|
SPIKE-GENERICS.md |
Milestone 5's parametric polymorphism, run early and out of order as a spike. The spike succeeded and generics landed, so this is the report of finished work rather than a live plan — but its findings about where the cost falls are still the reason the implementation looks the way it does. Historical, findings still stand. |
overview.md |
The first brainstorm, from before the language had S-expressions. It says in its own first line that it is superseded and no longer accurate. Kept for history only; its table of what changed is the only part worth reading. Superseded. |
handoffs/
One report per work session, each written by whoever held the branch at the time. They are the
operational record: what was attempted, what was measured, what was decided without being able to ask,
and what was left open for the next lane. They are all historical the moment they are written — a handoff
describes a session that has ended — but they are cited by name from source comments and from NEXT.md,
because the reasoning behind a guard or a calling convention is often only written down once and this is
where it was written.
Six of them are the hand-written x86-64 backend, read in the order the work happened:
handoffs/HANDOFF-x86-rt.md set the remaining-items list that the four after it close, handoffs/HANDOFF-x86-redef.md
built the redefinition emitter, handoffs/HANDOFF-x86-aggregates.md took that across the struct boundary,
handoffs/HANDOFF-x86-guards.md settled the two guards nothing reaches, handoffs/HANDOFF-x86-debug.md added debug
information, and handoffs/HANDOFF-x86-cost.md measured what the backend costs and set the survey running on its
own so a refusal cannot sit unnoticed again.
The other six sessions are unrelated to each other. handoffs/HANDOFF-arith.md is why a divide by zero is a condition
rather than a SIGFPE. handoffs/HANDOFF-raylib-ports.md is the running record of the last two raylib example
ports, whose lasting findings were folded into PORTING.md, and handoffs/HANDOFF-cimport-ptr.md is the arm
cimport.ml's header check had been promising in a comment and not implementing — which is what those two ports
found, worked around and wrote up. handoffs/HANDOFF-devtest-noise.md is the linker
error dune test used to print on every run. handoffs/HANDOFF-emacs-flake.md is the test_emacs flake that
turned out to be SIGPIPE killing the daemon mid-reply, and it is worth reading for the two mechanisms it
rules out as much as for the one it found. handoffs/HANDOFF-tidy.md is this reorganisation.