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A Tutorial on Parallel and Concurrent Programming in Haskell Simon Peyton Jones and Satnam Singh Microsoft Research Cambridge simonpj@ satnams@ Abstract. This practical tutorial introduces the features available in Haskell for writing parallel and concurrent programs. We first describe how to write semi-explicit parallel programs by using annotations to ex- press opportunities for parallelism and to help control the granularity of parallelism for effective execution on modern operating systems and pro- cessors. We then describe the mechanisms provided by Haskell for writing explicitly parallel programs with a focus on the use of software transac- tional memory to help share information between threads. Finally, we show how nested data parallelism can be used to write deterministically parallel programs which allows programmers to use rich data types in data parallel programs which are automatically transformed into flat data parallel versions for efficient execution on multi-core processors. 1 Introduction The introduction of multi-core processors has renewed interest in parallel func- tional programming and there are now several interesting projects that explore the advantages of a functional language for writing parallel code or implicitly par- alellizing code written in a pure functional language. These lecture notes present a variety of techniques for writing concurrent parallel programs which include existing techniques based on semi-implicit parallelism and explicit thread-based parallelism as well as more recent developments in the areas of software trans- actional memory and nested data parallelism. We also use the terms parallel and concurrent with quite specific meanin