Type Inference

• The compiler will infer types for expressions, and for constant and function declarations automatically. Type annotations are rarely required.
• Type annotations can always be provided and will be checked for correctness by the compiler.
• Type signatures for top-level declarations are considered good style. They serve as invaluable machine-checked interface documentation.
• You can use GHC(i) to obtain inferred types. Use :t often, but also try to train your own type inference capabilities over time – it will help you to understand errors with less effort.