fact: Definition rev {A} : selector A := fun l => let res := dreduce (@mrev', @mrev_append, @mapp) (mrev' l) in M.ret res.
imports: Strings.String ssrmatching.ssrmatching Mtac2(Logic Datatypes List Utils Logic intf.Sorts) Strings.String NArith.BinNat NArith.BinNatDef