Functional Patterns, Results, and Errors

These standards cover representing expected failure as a value (Result/Option) instead of exceptions, composing behaviour with delegates and higher-order functions instead of class hierarchies, and working correctly with closures, iterators, and immutable collections. Apply them whenever a method's failure is expected and recoverable, or when composing behaviour that would otherwise become a class hierarchy.

• Build Functional Types from Smart Constructors and Closed Unions
• Chain Async Operations Through Result
• Compose Result Values with Map/Bind/And/MapError
• Exceptions Are Dynamically Scoped
• Expose Immutable State via Persistent Collections
• Fast Immutable Design
• Implement GoF Patterns as Delegates and Higher-Order Functions
• Prefer Result Types Over Exceptions for Expected Failures
• The Option Type Instead of Nullable Reference Chains
• Understand Closures Capture Variables by Reference
• Use a Result<T, TError> Type for Expected Failures
• Write Iterator Methods with yield return