Eli Bendersky's tutorial demonstrates how monads in Lean 4 can elegantly handle failure propagation in expression evaluators, replacing tedious nested match statements with cleaner compositional patterns. The article walks through a concrete motivating example using safe division and the Option type to illustrate the core problem monads solve.
Background
Monads are a fundamental abstraction in functional programming used to compose computations with side effects such as error handling, state, or IO. Lean 4 incorporates monadic constructs from languages like Haskell while supporting formal verification workflows.
- Source
- Lobsters
- Published
- Nov 11, 2026 at 06:13 PM
- Score
- 6.0 / 10