Type Inference by Example

Type inference is the process by which Haskell ‘guesses’ the types for variables and functions, without you needing to specify these types explicitly. Many functional languages feature type inference.

There is lots of theory behind type inference — Hindley-Milner type systems and Unification.

However we don’t need this level of detail. Like most car drivers, we don’t know too much about how the engine works — we just drive the car. This video gives a high-level intuition for how type inference operates, which is all we need to grasp for now.