Effect by Example: Reading Files

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import { Effect } from "effect";
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import { FileSystem } from "@effect/platform";
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import { NodeFileSystem } from "@effect/platform-node";
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declare const main: Effect.Effect<void, never, FileSystem.FileSystem>;
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const runnable = main.pipe(Effect.provide(NodeFileSystem.layer));

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import { Effect, Console } from "effect";
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import { FileSystem } from "@effect/platform";
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const main = Effect.gen(function* () {
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  const fs = yield* FileSystem.FileSystem;
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  yield* fs.writeFileString("file.txt", "Hello, world!");
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  const bytes = yield* fs.readFile("file.txt");
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  console.log(bytes);
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});
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import { NodeContext } from "@effect/platform-node";
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await main.pipe(Effect.provide(NodeContext.layer), Effect.runPromise);

<Buffer 48 65 6c 6c 6f 2c 20 77 6f 72 6c 64 21>

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import { Effect, Console } from "effect";
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import { FileSystem } from "@effect/platform";
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const main = Effect.gen(function* () {
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  const fs = yield* FileSystem.FileSystem;
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  yield* fs.writeFileString("file.txt", "Hello, world!");
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  const string = yield* fs.readFileString("file.txt");
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  console.log(string);
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});
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import { NodeContext } from "@effect/platform-node";
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await main.pipe(Effect.provide(NodeContext.layer), Effect.runPromise);

Hello, world!

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import { Effect } from "effect";
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import { FileSystem } from "@effect/platform";
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const main = Effect.gen(function* () {
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  const fs = yield* FileSystem.FileSystem;
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  yield* fs.writeFileString("file.txt", "Hello, world!");
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  // opening a file is a scoped operation
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  const file = yield* fs.open("file.txt");
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  // seek 4 bytes from the start
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  yield* file.seek(4, "start");
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  // read into a buffer
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  const buffer = new Uint8Array(5);
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  const sizeRead = yield* file.read(buffer);
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  console.log(buffer);
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  // seek 2 bytes from the current position
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  yield* file.seek(2, "current");
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  // read and allocate a buffer for result
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  const buffer2 = yield* file.readAlloc(5);
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  console.log(buffer2);
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  // ensures the file is closed after the effect ends
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}).pipe(Effect.scoped);
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import { NodeContext } from "@effect/platform-node";
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await main.pipe(Effect.provide(NodeContext.layer), Effect.runPromise);

Uint8Array(5) [ 111, 44, 32, 119, 111 ]
{
  _id: "Option",
  _tag: "Some",
  value: {
    type: "Buffer",
    data: [ 100, 33 ],
  },
}