The Fifth International Symposium on Practical Aspects of Declarative L- guages (PADL 2003) was held in New Orleans on 13-14 January 2003. It was colocatedwiththe30thAnnualACMSymposiumonPrinciplesofProgramming Languages(POPL2003). We received 57 submissions, a record for PADL. One of the strengths of PADL is that it draws papers from both sides of the declarative divide, from boththefunctionalandlogicprogrammingcommunities.Ofthe57submissions, 25werefunctionaland32werelogical,withsomenotableoverlaps. The program committee was divided on the approach to take to the con- rence.Thosefromthelogicprogrammingcommunitypreferredtohaveparallel sessionsinordertoacceptmorepapers,thosefromthefunctionalprogramming communitypreferredtoavoidparallelsessionsthoughitmeantacceptingfewer papers. We decided to ?nd strength in diversity, and experiment with taking both paths. We accepted 8 papers on functional programming, each presented initsownslot,and15papersonlogicprogramming,10ofwhicharepresentedin parallelsessions.Wefeltthatpapersfrombothcommunitieswerecomparablein quality.Theratioof4hoursoffunctionaltalksto5hoursoflogictalksmatches theratioofsubmissions.
WhilemostpaperssubmittedtoPADLaretraditionalresearchpapers,some weresubmittedasApplicationLettersorDeclarativePearls.Traditionalpapers maybejudgedonwhethertheypresentacrispnewresearchresult;Application Lettersmaybejudgedaccordingtotheinterestintheapplicationandthenovel useofdeclarativelanguages;andDeclarativePearlsmaybejudgedaccordingto theeleganceofthedevelopmentandtheclarityoftheexpression. This year PADL instituted a "Most Practical" paper award, for the paper that best exempli?ed the goals of PADL. The award went to "Data mining the yeast genome in a lazy functional language", Amanda Clare and Ross D. King,UniversityofWales,Aberystwyth,whichdescribesareal-wordapplication runningonmultiprocessors,drawingontechniquesfromboththefunctionaland logicprogrammingcommunities. Special thanks are due: to Shriram Krishnamurthi, Dave Tucker, and Paul Graunke of Brown University, for running the website of the PADL submission andreviewprocess(seeKrishnamurthi'sinvitedtalkinthisvolume);toMartina SharpofAvayaLabsandKimberlyVollofSimonFraserUniversity,forhelpwith preparingthisvolume;andtoGopalGuptaoftheUniversityofTexasatDallas, for serving as general chair.
We thank Avaya Labs, Brown University, Simon FraserUniversity,Universit' edeProvence,andtheUniversityofTexasatDallas fortheirsupport. Ourthankstotheprogramcommitteemembersandrefereesfortheirrev- wingandfortheiradvice.Finally,ourthankstoallthosewhosubmittedpapers toorparticipatedinPADL2003.