Patterns and anti-patterns in functional error handling

Functional programming has redefined our approach to error handling. By bringing errors into the realm of data, we ensure safer, more predictable code. But as with any paradigm, there are right ways and pitfalls. Let’s look at the patterns that can help you and also the anti-patterns.

There are several patterns that can help you handle errors in a more functional way. These patterns are designed to enhance the quality, readability, and maintainability of your code. Here are some of the key patterns to consider:

• Rich custom error types

  Instead of generic strings or codes, use detailed types to describe errors:

  public Result<User, UserError> GetUser(int id)
  {
      if (id < 0)
          return Result.Fail<User, UserError>(new InvalidIdError(id));
      // ... other checks and logic ...
  }

• Leveraging composition

  Chain multiple...