WTF is Monetic Error Handling

Introduction

• Overview of error handling in different programming languages.
• Highlight the use of monads as a data structure to handle errors in a type-safe manner.

JavaScript Error Handling

• Example: Reading a non-existent file using readFileSync from Node's file system module.
• JavaScript error handling issues:
  • No indication of potential errors in IDE or documentation.
  • Inconsistent behavior with libraries (e.g., some throw errors, some return null/undefined).

Java Error Handling

• Java uses checked exceptions that are checked at compile time.
• Methods that can throw exceptions must either catch them or continue throwing them.
• Example: Reading a file using readAllBytes.
  • Uses throws IOException for checked exceptions.

Rust Error Handling

• No exceptions, only panics in exceptional circumstances.
• Uses monads like Result and Option to indicate success or failure.
• Example: Reading a file with read_to_string, using unwrap and unwrap_or.
  • unwrap: Accesses result if successful; otherwise, it causes a panic.
  • unwrap_or: Provides a default value if the operation fails.
• Use map for chaining and transformations.

Rust's Option Type

• Used in cases where a value may or may not exist.
• Example with find_user_by_id function:
  • Return Some(user) if found, None if not.
  • Use unwrap_or for default values.

Monads in Java

• Java has Optional but no Result type.
• Example: getOptional method using Optional<String>.
  • Use map and orElse for transformations and default values.

Monads in JavaScript

• JavaScript lacks monads in the standard library.
• Use libraries like fp-ts to implement monads.
• Example: getOption function using Option from fp-ts.
  • Use pipe, map, and default handling for operations.

Conclusion

• Monads provide a type-safe way to handle errors and indicate success or failure without relying on documentation.
• Monads can make code more reliable and easier to read by providing consistent error handling mechanisms.