# Session summary — 2026-10-01 (b): showcase21 — suffixes, coroutines, library

Suite **174/174**; self-hosting fixpoint **OK** (image
**2,785,569 bytes**).  `master`, tree clean except the user's
uncommitted `compiler/toto.mod`.

This step tours the three features landed this session on items 2, 4
and 6 of the gaps list (1 `GOTO`, 3 generics, 5 multiple inheritance
were deliberately skipped).

## Steps, tags and headline commits

| Step | Tag | Commit | What |
| --- | --- | --- | --- |
| Language + library | `v3-resultsfx-coroutines-lib` | `31adfc3` | suffixes, coroutines, core library |
| Notes | — | `e844223` | session summary |
| `LongIO` | — | `b1a52db` | channel-based LONGREAL I/O |
| Showcase | `v3-showcase21` | (this commit) | showcase21 end to end |

## 1. Result suffixes

`F()^`, `F()[i]`, `F().field` — components applied to a function-call
result (`ResultComp` in `M2.atg`, inside the call group so the Coco/R
grammar stays LL(1)-clean).  A final scalar is loaded with `ElemLoad`;
aggregates stay as their descriptor address.  Expression context only.

## 2. PIM coroutines

`PROCESS` plus `NEWPROCESS`/`TRANSFER`/`IOTRANSFER` are predefined in
`SYSTEM` (with a new parameterless `PROC` type) and bind to
`ucontext`-backed helpers in `runtime/syslib/shim.c`.  Coroutine bodies
are called with a 0 static link (module-level procedures).

## 3. Standard library

gm2/ISO names added under `stdlib/`: `ConvTypes`, `IOConsts`,
`SIOResult`, `TERMINATION`, `StrIO`, `InOut`, `StdIO`, `WholeStr`,
`RealStr`, `LongStr`, `LongMath`, `LongIO`, `STextIO`, `SWholeIO`,
`SRealIO`, `DynamicStrings` (core) and `SysStorage`.  Backend fixes
alongside: procedure values / `LONGINT` are 8-byte in array load/store
and the parameter prologue; driver session file cap 32 → 128;
`Math.ln`/`arctan` wrap `log`/`atan`.

## 4. Showcase

`compiler/tests/showcase21.mod` (`Showcase21`, exit 42) exercises:

- **result suffixes** — `GetRec()^.a + GetRec()^.b = 42`,
  `GetArr()^[i]` sums to 4, then `40 + 2 + 2 - 2 = 42`;
- **coroutines** — `Ping`/`Pong` ping-pong via `TRANSFER`, hand control
  back to the main process after five hits;
- **library** — `RealStr.RealToFixed(42.0, 0, num)` gives `"42"`,
  `LongMath.sqrt(1764.0)` round-trips to 42, and `WholeStr.CardToStr`
  + `DynamicStrings` build the label.

```
showcase21 total=42
```

## Tests (174, was 171)

New this session: `t_resultsfx`, `t_coroutine`, `t_dynstr`, `library1`
(16-module session) and `Showcase21`.  Full suite green.

## Resume

```sh
cd .../m2compiler-V3
./bootstrap/fixpoint.sh                       # FIXPOINT OK
cd compiler && ./build.sh && ./run_tests.sh   # 174/174
```

## Remaining

`GOTO`/labels, generics, multiple inheritance (deliberate), full
forward variables, statement-context result suffixes, and the
channel/device library holes (`LongWholeIO`, `wrapclock`/`wraptime`/
`wrapc`, `TimeString`, `ChanConsts`/`GenDevIF`/`DeviceTablePtr`/
`StdChans`/`StreamFile`/`FIO`).