fact: Definition refineList (d : SplitDirection) (l : list SplitPath) : list SplitPath := map (@tl SplitDirection) (filter (fun p => match hd_error p with | Some d' => eq_dir_b d d' | _ => false end) l).
imports: mathcomp.ssreflect.ssreflect mathcomp(ssrfun ssrbool ssrnat eqtype) ZArith LazyList Tactics List