fact: Fixpoint enum_bintreesz_leq n := if n is n'.+1 then let rec := enum_bintreesz_leq n' in let listn := flatten [seq [seq BinNode tl tr | tl <- nth [::] rec i, tr <- nth [::] rec (n' - i)] | i <- iota 0 n'.+1] in rcons rec listn else [:: [:: BinLeaf]].
imports: HB(structures) mathcomp(all_ssreflect) tools combclass ordtype