Haskell vs OCaml: What are the differences?

1. Type System: Haskell is statically typed, while OCaml is both statically and strongly typed. Haskell uses type inference to deduce types, which can lead to more concise code, while OCaml requires explicit type annotations. This difference can affect how developers write and interact with the codebase.

2. Lazy vs. Eager Evaluation: Haskell is known for its lazy evaluation strategy, where expressions are not evaluated until their results are needed. In contrast, OCaml uses eager evaluation, meaning expressions are evaluated as soon as they are encountered. This difference can impact the performance and behavior of the programs written in these languages.

3. Module System: Haskell has a hierarchical module system, allowing developers to organize their code into a tree-like structure. On the other hand, OCaml uses a flat module system, which can simplify the organization of code but may lead to potential naming conflicts. This distinction can influence how developers structure and maintain their projects.

4. Concurrency Support: Haskell has built-in support for lightweight threads and software transactional memory (STM), making it well-suited for concurrent programming. In contrast, OCaml provides facilities for concurrent programming through libraries like Lwt and Async. This difference affects how developers handle parallelism and concurrency in their applications.

5. Language Philosophy: Haskell emphasizes purity and immutability, encouraging developers to write functions without side effects. OCaml, while supporting functional programming paradigms, also allows mutable data structures and imperative programming styles. This distinction can impact how developers approach problem-solving and design solutions.

6. Library Ecosystem: Haskell has a strong emphasis on functional programming libraries and tools, with a focus on type-level and category theory. OCaml, on the other hand, has a broader ecosystem that includes support for imperative programming and system-level development. This difference can influence the availability of resources and support for specific programming tasks.

In Summary, Haskell and OCaml differ in their type systems, evaluation strategies, module systems, support for concurrency, language philosophies, and library ecosystems.