// types — error union, mode/whence enums, reader/writer/closer
// fn-type aliases. Project #94 fold-1 step (d) (drew Fold D); the
// fn-aliases re-targeted from *stream → vstream as part of fold-e1
// (vtable port in stream.ww).
//
// Hare splits the io module across stream.ha + types.ha and ww does
// the same: lib/io/io.ww owns the (pre-vtable) `stream`, `eof`, and
// `underread` shapes; lib/io/stream.ww owns the Hare vtable port
// (`vtable`, `vstream`, `st_read`/`st_write`/`st_close` dispatch);
// this file owns the surrounding port. The three files share
// `package io;` so cross-file refs resolve via the dir-enum concat
// order (io.ww < stream.ww < types.ww — `vstream` lands before the
// reader/writer/closer aliases below).
//
// Deferrals (drew-signed): `handle`, `seeker`, `copier`, `strerror`
// land with fold-e2+ (need the `handle` sum). 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/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
// st_read/st_write dispatchers in stream.ww return
// `errors.unsupported` when the matching vtable slot is unset, so the
// variant lands here directly.
export type error = !(errors.unsupported | underread | nomem);

// ref/hare/io/types.ha:46. `eof` (not Hare's `done`) per the io.ww:8
// rationale; lifts to `done` with #93. `vstream` 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: vstream, buf: []u8) (size | eof | error);

// ref/hare/io/types.ha:51. No `const` qualifier — ww has none, and
// lib/io/io.ww:30 + lib/sort/sort.ww:18 drop it the same way.
export type writer = fn(s: vstream, buf: []u8) (size | error);

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