A Haskell developer designs, creates, and maintains software applications using the functional programming language, Haskell. They utilize its strong static typing, non-strict semantics, and rich expressiveness to build robust, efficient, and maintainable software. Their tasks include writing and debugging code, testing software, and integrating applications with other systems. Haskell developers often work on complex data analysis, high reliability systems, compilers, and concurrent programming due to Haskell's suitability for these tasks. They also collaborate with other team members, sharing expertise and problem-solving methods, and ensuring the software meets user requirements and adheres to high-quality standards.