ww/lib/io/types.ww

// types — error union, mode/whence enums, reader/writer/closer
// fn-type aliases. Project #94 fold-eFinal; the fn-aliases target
// `stream` (= `*vtable`, the single io surface).
//
// Hare splits the io module across stream.ha + types.ha and ww does
// the same: lib/io/io.ww owns the `eof` and `underread` tags;
// lib/io/stream.ww owns the vtable surface (`vtable`, `stream`,
// `read`/`write`/`close` dispatch); this file owns the surrounding
// port. The four files share `package io;` so cross-file refs
// resolve via the dir-enum concat order (io.ww < stream.ww < types.ww
// — `stream` lands before the reader/writer/closer aliases below).
//
// Deferrals (drew-signed): `copier`, `strerror` (the #5 list's
// `handle` + `seeker` landed with the #5 arc and the memio-seeker
// port). Hare's `EOF = done` stays as `io.eof` until the `done`
// singleton ships (#93).

package io;

import errors;

// ref/hare/io/types.ha:29-34. RDWR is spelled `3` rather than Hare's
// `READ | WRITE` because the ww parser doesn't fold expressions in
// enum value positions; the value SSoT stays the same bitfield.
export type mode = enum u8 {
	NONE  = 0,
	READ  = 1,
	WRITE = 2,
	RDWR  = 3,
};

// ref/hare/io/types.ha:37-41. Hare leaves the underlying implicit;
// ww requires one. i32 matches the off type that fold-e2 will plug
// into the seeker signature.
export type whence = enum i32 {
	SET = 0,
	CUR = 1,
	END = 2,
};

// ref/hare/io/+linux/platform_file.ha:13. Hare's `file = int`; on
// linux/x86_64 Hare's `int` is 32-bit, but ww's `int` is an 8B machine
// word, so a literal `int` here would be width-wrong for a fd. i32 is
// width-faithful to Hare's real fd width (USER-ruled 2026-05-31).
export type file = i32;

// ref/hare/io/arch+x86_64.ha:6. ABI-compatible with POSIX off_t.
export type off = i64;

// ref/hare/io/handle.ha:12. Hare spells it `(file | *stream)`; ww's
// `stream` is already `*vtable` (the #94 collapse absorbed Hare's
// `*stream` indirection), so the faithful ww payload is `(file |
// stream)`, NOT a literal `*stream` which would be a double-pointer.
export type handle = (file | stream);

// ref/hare/io/types.ha:11 spreads `...errors::error` into the union;
// ww enumerates the tags explicitly (ken's #204-block — spread of an
// errors-side tagged into this union triggers a wrapper-vs-flatten
// layout mismatch; #199b layout-extension is the deferred fix). The
// read/write dispatchers in stream.ww return `errors.unsupported`
// when the matching vtable slot is unset, so the variant lands here
// directly. `errors.invalid` rides the memio-seeker port (Hare's
// memio seek returns errors::invalid on out-of-bounds,
// ref/hare/memio/stream.ha:134-136); appended last so existing
// member tags stay put.
export type error = !(errors.unsupported | underread | nomem | errors.invalid);

// ref/hare/io/types.ha:46. `eof` (not Hare's `done`) per the io.ww
// rationale; lifts to `done` with #93. `stream` forward-refs the
// `*vtable` alias in stream.ww — the dispatcher receives the vtable
// pointer directly (Hare's stream.ha:33 + types.ha:46 collapse).
export type reader = fn(s: stream, buf: []u8) (size | eof | error);

// ref/hare/io/types.ha:51. No `const` qualifier — ww has none, and
// lib/sort/sort.ww:18 drops it the same way.
export type writer = fn(s: stream, buf: []u8) (size | error);

// ref/hare/io/types.ha:55.
export type closer = fn(s: stream) (void | error);

// ref/hare/io/types.ha:76. Hare's `fn(s: *stream, off: off, w: whence)`;
// ww's `stream` is already `*vtable` (the #94 collapse), so the param is
// `stream` directly, mirroring the reader/writer/closer aliases above.
export type seeker = fn(s: stream, off: off, w: whence) (off | error);