avoid to from bytes conversion for some string operations: such conversion is expensive in Backends which has different representation for string and bytes
avoid to from bytes conversion for some string operations: such conversion is expensive in Backends which has different representation for string and bytes

gerdstolpmann/ocaml,msprotz/ocaml,gerdstolpmann/ocaml,msprotz/ocaml,gerdstolpmann/ocaml,yunxing/ocaml,yunxing/ocaml,msprotz/ocaml,gerdstolpmann/ocaml,msprotz/ocaml,gerdstolpmann/ocaml,yunxing/ocaml,yunxing/ocaml,msprotz/ocaml,yunxing/ocaml