effect-patterns-platform

Effect-TS Patterns: Platform

This skill provides 6 curated Effect-TS patterns for platform. Use this skill when working on tasks related to:

• platform
• Best practices in Effect-TS applications
• Real-world patterns and solutions

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🟢 Beginner Patterns

Platform Pattern 4: Interactive Terminal I/O

Rule: Use Terminal for user input/output in CLI applications, providing proper buffering and cross-platform character encoding.

Good Example:

This example demonstrates building an interactive CLI application.

import { Terminal, Effect } from "@effect/platform";

interface UserInput {
  readonly name: string;
  readonly email: string;
  readonly age: number;
}

const program = Effect.gen(function* () {
  console.log(`\n[INTERACTIVE CLI] User Information Form\n`);

  // Example 1: Simple prompts
  yield* Terminal.writeLine(`=== User Setup ===`);
  yield* Terminal.writeLine(``);

  yield* Terminal.write(`What is your name? `);
  const name = yield* Terminal.readLine();

  yield* Terminal.write(`What is your email? `);
  const email = yield* Terminal.readLine();

  yield* Terminal.write(`What is your age? `);
  const ageStr = yield* Terminal.readLine();

  const age = parseInt(ageStr);

  // Example 2: Display collected information
  yield* Terminal.writeLine(``);
  yield* Terminal.writeLine(`=== Summary ===`);
  yield* Terminal.writeLine(`Name: ${name}`);
  yield* Terminal.writeLine(`Email: ${email}`);
  yield* Terminal.writeLine(`Age: ${age}`);

  // Example 3: Confirmation
  yield* Terminal.writeLine(``);
  yield* Terminal.write(`Confirm information? (yes/no) `);
  const confirm = yield* Terminal.readLine();

  if (confirm.toLowerCase() === "yes") {
    yield* Terminal.writeLine(`✓ Information saved`);
  } else {
    yield* Terminal.writeLine(`✗ Cancelled`);
  }
});

Effect.runPromise(program);

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Rationale:

Terminal operations:

• readLine: Read single line of user input
• readPassword: Read input without echoing (passwords)
• writeLine: Write line with newline
• write: Write without newline
• clearScreen: Clear terminal