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Read and write files

Swap node:fs/promises for @antithrow/node/fs/promises — same shape, same arguments, Result return.

Read​

import { readFile } from "@antithrow/node/fs/promises";

const contents = await readFile("/etc/hostname", "utf-8");

if (contents.isOk()) {
	use(contents.value);
} else if (contents.error.code === "ENOENT") {
	createDefault();
}

The error is typed as NodeJS.ErrnoException, so branching on .code ("ENOENT", "EACCES", "EISDIR", …) is fully typed.

Write​

import { writeFile } from "@antithrow/node/fs/promises";

const wrote = await writeFile("/tmp/out.txt", "hello", "utf-8");
if (wrote.isErr() && wrote.error.code === "EACCES") {
	fallbackToTempDir();
}

writeFile returns Result<void, NodeJS.ErrnoException>.

Compose read + write​

import { readFile, writeFile } from "@antithrow/node/fs/promises";

const copied = await readFile(source)
	.andThen((buf) => writeFile(target, buf));

andThen short-circuits if the read fails.

Create a directory if missing​

import { mkdir, writeFile } from "@antithrow/node/fs/promises";

await mkdir(dir, { recursive: true }).andThen(() => writeFile(path, data));

With { recursive: true }, mkdir no longer errors on EEXIST, so the andThen always reaches writeFile.

See also​