An educational article explaining the fundamental difference between foldl and foldr in Haskell: they traverse lists in the same left-to-right order, but differ in associativity—foldl is left-associated while foldr is right-associated. The article illustrates how this impacts behavior in strict vs. lazy evaluation contexts.
Background
This is a re-publication of a seminal tutorial originally posted on Hasura's GraphQL Engine repo in 2019. The article serves as a foundational reference for understanding Haskell folding operations.
- Source
- Lobsters
- Published
- Sep 30, 2026 at 08:47 PM
- Score
- 5.0 / 10