The 13th International Workshop on the Implementation of Functional L- guages (IFL 2001) was hosted this year by Ericsson in Stockholm. The growing importance of functional languages in Ericsson products makes strong coope- tion with universities attractive, and hosting IFL was one nice wayto interact. Consecutive to IFL 2001, Ericsson had organized the annual Erlang User Conf- ence, which over 100 (mostlyindustrial) users of the functional language Erlang attended. All participants of IFL 2001 were invited to stayfor that conference as well. In this way, academia got a better insight into the potential of functional languages in industry, and industry got a feeling for upcoming ideas in this area. IFL 2001 was held in September 2001 and attracted 43 researchers from the international functional language community. During the 3 days of the workshop, theypresented no fewer than 28 contributions. The contributions covered topics on the implementation, and also the use of functional languages. This volume follows the lead of the last ?ve IFL workshops in publishing a high-qualitysubset of the contributions in Springer's Lecture Notes in C- puter Science series.
All speakers at the workshop were invited to submit a paper afterwards. These submissions were reviewed bythree or four referees and th- oughlydiscussed bythe program committee. From all submissions, 11 papers were selected for publication in this volume.