月度归档： 2025 年 8 月

A monad demo given by AI

// Generic Monad structure
class Monad {
  constructor(value) {
    this.value = value;
  }

  // Bind: chains computations that return a Monad
  bind(fn) {
    return fn(this.value);
  }

  // Unit: wraps a value in the Monad
  static of(value) {
    return new Monad(value);
  }

  // For debugging
  get() {
    return this.value;
  }
}

// Example: Maybe Monad
class Maybe extends Monad {
  bind(fn) {
    if (this.value == null) {
      return new Maybe(null);
    }
    return fn(this.value);
  }

  static of(value) {
    return new Maybe(value);
  }

  getOrElse(defaultValue) {
    return this.value == null ? defaultValue : this.value;
  }
}

// Demo: chaining computations with Monad
const double = x => Monad.of(x * 2);
const increment = x => Monad.of(x + 1);

const result = Monad.of(5)
  .bind(double)      // 10
  .bind(increment);  // 11

console.log(result.get()); // Output: 11

// Demo: chaining with Maybe Monad
const safeDivide = x => x === 0 ? Maybe.of(null) : Maybe.of(10 / x);

const maybeResult = Maybe.of(2)
  .bind(safeDivide)       // 10 / 2 = 5
  .bind(x => Maybe.of(x + 3)); // 8

console.log(maybeResult.getOrElse("fail")); // Output: 8

const maybeFail = Maybe.of(0)
  .bind(safeDivide)       // null
  .bind(x => Maybe.of(x + 3));

console.log(maybeFail.getOrElse("fail")); // Output: "fail"

maybe functor

class Maybe {
  constructor(value) {
    this.value = value;
  }

  // Functor map: applies a function if value is not null/undefined
  map(fn) {
    if (this.value === null) {
      return new Maybe(null);
    }
    return new Maybe(fn(this.value));
  }

  // getOrElse: safely extract value with a fallback
  getOrElse(defaultValue) {
    return this.value === null ? defaultValue : this.value;
  }

  // static helpers for convenience
  static of(value) {
    return new Maybe(value);
  }

  static nothing() {
    return new Maybe(null);
  }
}

// Example usage:
const maybeNumber = Maybe.of(5)
  .map(n => n * 2)
  .map(n => n + 1);

console.log(maybeNumber.getOrElse(0)); // Output: 11

const maybeNull = Maybe.of(null)
  .map(n => n * 2);

console.log(maybeNull.getOrElse(0)); // Output: 0

追回来了

2025-07-31

大端序，小端序

Examples with the number 0x12345678 (i.e., 305 419 896 in decimal):

little-endian: 0x78 0x56 0x34 0x12
big-endian: 0x12 0x34 0x56 0x78
mixed-endian (historic and very rare): 0x34 0x12 0x78 0x56

https://developer.mozilla.org/en-US/docs/Glossary/Endianness

2025-07-30

zig 这门语言似乎是和 rust 产生竞争，抢占 c 语言的市场

The primary goal of Zig is to be a better solution to the sorts of tasks that are currently solved with C. A primary concern in that respect is readability; Zig attempts to use existing concepts and syntax wherever possible, avoiding the addition of different syntax for similar concepts. Further, it is designed for “robustness, optimality and maintainability”, including a variety of features to improve safety, optimization, and testing.

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宝回老家了

2025-06-30

菜鸟面试官的一点思考

2025-06-26

“The boolean trap” is just one example of how seemingly simple modeling decisions can have unexpected consequences as systems grow. While booleans are perfect for their intended purpose – representing true/false technical states – they often fall short when applied to a domain. By choosing enums and enum sets we create code that is better prepared for the “real world”‘ of the problem domain.

Sometimes it’s better to rethink how we represent the state instead of blindly adding another boolean flag.

https://katafrakt.me/2024/11/09/booleans-are-a-trap

乱语：这位老哥说在领域模型内，使用布尔值不是很好，得用枚举或者是状态机。

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