// types — error union, mode/whence enums, reader/writer/closer
// fn-type aliases. Project #94 fold-1 step (d) (drew Fold D).
//
// 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; this file owns the surrounding port. Both
// files share `package io;` so forward refs (e.g. reader → stream)
// resolve via the dir-enum concat order.
//
// Deferrals (drew-signed): `handle`, `seeker`, `copier`, `strerror`
// land with fold-e (need the `handle` sum). Hare's `EOF = done`
// stays as `io.eof` until the `done` singleton ships (#93).

package io;

// 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-e 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;
// lib/errors isn't ported yet, so the union carries only the tags
// observable in this fold — `underread` (from io.ww) and the
// predeclared `nomem` (#29, type.c:72 / check.ww:78).
export type error = !(underread | nomem);

// ref/hare/io/types.ha:46. `eof` (not Hare's `done`) per the io.ww:8
// rationale; lifts to `done` with #93. `*stream` forward-refs the
// pre-vtable struct in io.ww — same cross-file pattern Hare uses.
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/io/io.ww:30 + lib/sort/sort.ww:18 drop 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);