Koen Claessen Colin Runciman Olaf Chitil John Hughes Malcolm Wallace Testing and Tracing Lazy Functional Programs Using QuickCheck and Hat. 59-99 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2638&spage=59 2002 conf/afp/2002 Advanced Functional Programming db/conf/afp/afp2002.html#ClaessenRCHW02