This volume presents the revised lecture notes of selected talks given at the Fourth Central European Functional Programming School, CEFP 2011, held in June 2011 in Budapest, Hungary. The 11 revised full papers presented were carefully reviewed by experts on functional programming and revised based on the reviews. The lectures cover a wide range of distributed and multicore functional programming subjects. The last 2 papers are selected papers of the PhD Workshop organized for the participants of the summer school.

A Programming Tutor for Haskell. - Defining Multi-user Web Applications with iTasks. - Reasoning about I/O in Functional Programs. - Eden-Parallel Functional Programming with Haskell . - Single Assignment C (SAC): High Productivity Meets High Performance. - Reasoning about Multi-process Systems with the Box Calculus . - Parallel and Concurrent Programming in Haskell . - Feldspar: Application and Implementation. - Static Analysis of Complex Software Systems Implemented in Erlang . - Extending Little Languages into Big Systems . - Some New Approaches in Functional Programming Based on Categories .