Hi. I've sent a patch some time ago that made it possible to use paredit in REPL window without breaking history. It changed the behavior of slime-repl-matching-input-regexp so that the text between the start of current REPL input and the caret is used for history search. The patch was applied on 2006-09-01 by Nikodemus Siivola but later reverted due to some problems that it caused (there was a vague reference to complaints on #lisp). Well, now I had to repatch my copy of slime.el... No big problem with that, but I just wonder what were these negative consequences ? Maybe slime-repl-matching-input-regexp behavior should be made customizable?..
Ivan