Sorry, forgot to attach the source code. L.S., Hugs gives the following error message when running the attached program: Program error: Program error: pattern match failure (288112 reductions, 525181 cells, 9 garbage collections) INTERNAL ERROR: Error in graph This happens after reading 508 files; heap space is 250000. The problem most probably stems from the return of function collectFileData, as this was the last changed part. I am runnnig Hugs Nov 2003 on Windos 98. -- Best regards, Henk-Jan van Tuyl