diff --git a/.ocamlinit b/.ocamlinit
index 73ae4b14..bc131fd1 100644
--- a/.ocamlinit
+++ b/.ocamlinit
@@ -5,7 +5,7 @@
 #load "containers.cma";;
 #require "threads";;
 #load "thread_containers.cma";;
-open Gen.Infix;;
+open Sequence.Infix;;
 #install_printer Bencode.pretty;;
 (* vim:syntax=ocaml:
 *)
diff --git a/bij.ml b/bij.ml
index 7eadb52e..34310e6b 100644
--- a/bij.ml
+++ b/bij.ml
@@ -40,7 +40,8 @@ type _ t =
   | Quint : 'a t * 'b t * 'c t * 'd t * 'e t -> ('a * 'b * 'c * 'd * 'e) t
   | Guard : ('a -> bool) * 'a t -> 'a t
   | Map : ('a -> 'b) * ('b -> 'a) * 'b t -> 'a t
-  | Switch : ('a -> char * 'a inject_branch) * (char -> 'a extract_branch) -> 'a t
+  | Switch :  ('a -> string * 'a inject_branch) *
+              (string-> 'a extract_branch) -> 'a t
 and _ inject_branch =
   | BranchTo : 'b t * 'b -> 'a inject_branch
 and _ extract_branch =
@@ -69,10 +70,8 @@ let switch ~inject ~extract = Switch (inject, extract)
 
 (** {2 Exceptions} *)
 
-exception EOF
-
 exception EncodingError of string
-  (** Raised when decoding is impossible *)
+  (** Raised when encoding is impossible *)
 
 exception DecodingError of string
   (** Raised when decoding is impossible *)
@@ -80,7 +79,7 @@ exception DecodingError of string
 (** {2 Helpers} *)
 
 let fix f =
-  let rec bij = lazy (f (fun () -> Lazy.force bij)) in
+  let rec bij = lazy (f bij) in
   Lazy.force bij
 
 let with_version v t =
@@ -107,389 +106,103 @@ let hashtbl ma mb =
       h)
     (list_ (pair ma mb))
 
-(** {2 Source of parsing} *)
+(** {2 Translations} *)
 
-module type SOURCE = sig
-  type t
+module TrBencode = struct
+  module B = Bencode
 
-  val eof : t -> bool
-    (** End of input reached? *)
-
-  val cur : t -> char
-    (** Current char *)
-
-  val junk : t -> unit
-    (** Discard current char *)
-end
-
-module SourceStr = struct
-  type t = {
-    str : string;
-    mutable idx : int;
-  }
-
-  let create str =
-    { str;
-      idx = 0;
-    }
-
-  let eof t = t.idx = String.length t.str
-
-  let cur t =
-    if eof t then raise EOF else t.str.[t.idx]
-
-  let junk t =
-    if t.idx >= String.length t.str
-      then raise EOF
-      else t.idx <- t.idx + 1
-end
-
-module SourceStream = struct
-  type t = char Stream.t
-
-  let eof t = match Stream.peek t with
-    | None -> true
-    | Some _ -> false
-
-  let cur t = match Stream.peek t with
-    | None -> raise EOF
-    | Some c -> c
-
-  let junk t = Stream.junk t
-end
-
-module SourceChan = struct
-  type t = {
-    chan : in_channel;
-    buf : string;
-    mutable len : int;
-    mutable idx : int;
-  }
-
-  let create ?(bufsize=256) ic =
-    let t = { chan = ic;
-      buf = String.make bufsize ' ';
-      len = 0;
-      idx = 0;
-    } in
-    (* fill the buffer *)
-    t.len <- input t.chan t.buf 0 bufsize;
-    t
+  let rec encode: type a. bij:a t -> a -> B.t =
+  fun ~bij x -> match bij, x with
+  | Unit, () -> B.I 0
+  | String, s -> B.S s
+  | Int, i -> B.I i
+  | Float, f -> B.S (string_of_float f)
+  | Bool, b -> B.I (if b then 1 else 0)
+  | List bij', l ->
+    let l' = List.map (fun x -> encode ~bij:bij' x) l in
+    B.L l'
+  | Many bij', [] -> raise (EncodingError "many: got empty list")
+  | Many bij', l -> 
+    let l' = List.map (fun x -> encode ~bij:bij' x) l in
+    B.L l'
+  | Opt bij', None -> B.L []
+  | Opt bij', Some x -> B.L [encode ~bij:bij' x]
+  | Pair (bija, bijb), (a, b) ->
+    B.L [encode ~bij:bija a; encode ~bij:bijb b]
+  | Triple (bija, bijb, bijc), (a, b, c) ->
+    B.L [encode ~bij:bija a; encode ~bij:bijb b; encode ~bij:bijc c]
+  | Quad (bija, bijb, bijc, bijd), (a, b, c, d) ->
+    B.L [encode ~bij:bija a; encode ~bij:bijb b;
+         encode ~bij:bijc c; encode ~bij:bijd d]
+  | Quint (bija, bijb, bijc, bijd, bije), (a, b, c, d, e) ->
+    B.L [encode ~bij:bija a; encode ~bij:bijb b;
+         encode ~bij:bijc c; encode ~bij:bijd d;
+         encode ~bij:bije e]
+  | Guard (check, bij'), x ->
+    if not (check x) then raise (EncodingError "check failed");
+    encode ~bij:bij' x
+  | Map (inject, _, bij'), x ->
+    encode ~bij:bij' (inject x)
+  | Switch (inject, _), x ->
+    let key, BranchTo (bij',y) = inject x in
+    B.D (B.SMap.singleton key (encode ~bij:bij' y))
   
-  let eof t = t.len = 0
+  let rec decode: type a. bij:a t -> B.t -> a
+  = fun ~bij b -> match bij, b with
+  | Unit, B.I 0 -> ()
+  | String, B.S s -> s
+  | Int, B.I i -> i
+  | Float, B.S s ->
+    begin try
+      let f = float_of_string s in
+      f
+    with Failure _ ->
+      raise (DecodingError "expected float")
+    end
+  | Bool, B.I 0 -> false
+  | Bool, B.I _ -> true
+  | List bij', B.L l ->
+    List.map (fun b -> decode ~bij:bij' b) l
+  | Many bij', B.L [] ->
+    raise (DecodingError "expected nonempty list")
+  | Many bij', B.L l ->
+    List.map (fun b -> decode ~bij:bij' b) l
+  | Opt bij', B.L [] -> None
+  | Opt bij', B.L [x] -> Some (decode ~bij:bij' x)
+  | Opt bij', B.L _ ->
+    raise (DecodingError "expected [] or [_]")
+  | Pair (bija, bijb), B.L [a; b] ->
+    decode ~bij:bija a, decode ~bij:bijb b
+  | Triple (bija, bijb, bijc), B.L [a; b; c] ->
+    decode ~bij:bija a, decode ~bij:bijb b, decode ~bij:bijc c
+  | Quad (bija, bijb, bijc, bijd), B.L [a; b; c; d] ->
+    decode ~bij:bija a, decode ~bij:bijb b,
+    decode ~bij:bijc c, decode ~bij:bijd d
+  | Quint (bija, bijb, bijc, bijd, bije), B.L [a; b; c; d; e] ->
+    decode ~bij:bija a, decode ~bij:bijb b,
+    decode ~bij:bijc c, decode ~bij:bijd d,
+    decode ~bij:bije e
+  | Guard (check, bij'), x ->
+    let y = decode ~bij:bij' x in
+    if not (check y) then raise (DecodingError "check failed");
+    y
+  | Map (_, extract, bij'), b ->
+    let x = decode ~bij:bij' b in
+    extract x
+  | Switch (_, extract), B.D d when B.SMap.cardinal d = 1 ->
+    let key, value = B.SMap.choose d in
+    let BranchFrom (bij', convert) = extract key in
+    convert (decode ~bij:bij' value)
+  | _ -> raise (DecodingError "bad case")
 
-  let cur t =
-    if eof t
-      then raise EOF
-      else t.buf.[t.idx]
-
-  let junk t =
-    (if t.len = 0 then raise EOF);
-    t.idx <- t.idx + 1;
-    if t.idx = t.len
-      then begin  (* refill *)
-        t.idx <- 0;
-        t.len <- input t.chan t.buf 0 (String.length t.buf)
-      end
-end
-
-(** {2 Sink: Where to print} *)
-
-module type SINK = sig
-  type t
-  val write : t -> string -> int -> int -> unit  (* write substring [i..i+len] *)
-  val write_char : t -> char -> unit
-  val write_int : t -> int -> unit
-  val write_bool : t -> bool -> unit
-  val write_float : t -> float -> unit
-end
-
-module SinkBuf = struct
-  type t = Buffer.t
-
-  let write t str i len = Buffer.add_substring t str i len
-  let write_char t c = Buffer.add_char t c
-  let write_int t i = Printf.bprintf t "%d" i
-  let write_bool t b = Printf.bprintf t "%B" b
-  let write_float t f = Printf.bprintf t "%f" f
-end
-
-module SinkChan = struct
-  type t = out_channel
-
-  let write t str i len = output t str i len
-  let write_char t c = output_char t c
-  let write_int t i = Printf.fprintf t "%d" i
-  let write_bool t b = Printf.fprintf t "%B" b
-  let write_float t f = Printf.fprintf t "%f" f
-end
-
-(** {2 Encoding/decoding} *)
-
-module type ENCODE = sig
-  type sink
-  val encode : bij:'a t -> sink -> 'a -> unit
-end
-
-module type DECODE = sig
-  type source
-  val decode : bij:'a t -> source -> 'a
-end
-
-module SexpEncode(Sink : SINK) = struct
-  type sink = Sink.t
-
-  (* print escaped string to [sink] *)
-  let escape sink s =
-    (* function that escapes into the given sink *)
-    let rec really_escape sink s i =
-      if i = String.length s
-        then ()  (* done *)
-        else begin
-          (match s.[i] with
-          | '\n' -> Sink.write sink "\\n" 0 2
-          | '\t' -> Sink.write sink "\\t" 0 2
-          | ' ' | ')' ->
-            Sink.write_char sink '\\';
-            Sink.write_char sink s.[i];
-          | c ->
-            Sink.write_char sink c);
-          really_escape sink s (i+1)
-        end
-    in
-    (* search for a char to escape, if any *)
-    let rec search s i =
-      if i = String.length s
-        then Sink.write sink s 0 i (* no escaping needed *)
-        else match s.[i] with
-        | ' ' | '\t' | '\n' | ')' ->  (* must escape *)
-          Sink.write sink s 0 i;
-          really_escape sink s i (* escape starting at i *)
-        | _ -> search s (i+1)
-    in
-    search s 0
-
-  let encode ~bij sink x = 
-    let open Sink in
-    let rec encode : type a. a bij -> a -> unit = fun bij x ->
-      match bij, x with
-      | Unit, () -> ()
-      | String, s -> escape sink s
-      | Int, i -> Sink.write_int sink i
-      | Bool, b -> Sink.write_bool sink b
-      | Float, f -> Sink.write_float sink f
-      | List bij', l ->
-        Sink.write_char sink '(';
-        List.iteri
-          (fun i x -> (if i > 0 then Sink.write_char sink ' '); encode bij' x)
-          l;
-        Sink.write_char sink ')'
-      | Many _, [] -> failwith "Bij.encode: expected non-empty list"
-      | Many bij', l ->
-        Sink.write_char sink '(';
-        List.iteri
-          (fun i x -> (if i > 0 then Sink.write_char sink ' '); encode bij' x)
-          l;
-        Sink.write_char sink ')'
-      | Opt bij, None ->
-        encode (List bij) []
-      | Opt bij, Some x ->
-        encode (List bij) [x]
-      | Pair (bij_a, bij_b), (a, b) ->
-        Sink.write_char sink '(';
-        encode bij_a a;
-        Sink.write_char sink ' ';
-        encode bij_b b;
-        Sink.write_char sink ')'
-      | Guard (check, bij'), _ ->
-        (if not (check x) then raise (EncodingError ("check failed")));
-        encode bij' x
-      | Triple (bij_a, bij_b, bij_c), (a, b, c) ->
-        Sink.write_char sink '(';
-        encode bij_a a;
-        Sink.write_char sink ' ';
-        encode bij_b b;
-        Sink.write_char sink ' ';
-        encode bij_c c;
-        Sink.write_char sink ')'
-      | Quad (bij_a, bij_b, bij_c, bij_d), (a, b, c, d) ->
-        Sink.write_char sink '(';
-        encode bij_a a;
-        Sink.write_char sink ' ';
-        encode bij_b b;
-        Sink.write_char sink ' ';
-        encode bij_c c;
-        Sink.write_char sink ' ';
-        encode bij_d d;
-        Sink.write_char sink ')'
-      | Quint (bij_a, bij_b, bij_c, bij_d, bij_e), (a, b, c, d, e) ->
-        Sink.write_char sink '(';
-        encode bij_a a;
-        Sink.write_char sink ' ';
-        encode bij_b b;
-        Sink.write_char sink ' ';
-        encode bij_c c;
-        Sink.write_char sink ' ';
-        encode bij_d d;
-        Sink.write_char sink ' ';
-        encode bij_e e;
-        Sink.write_char sink ')'
-      | Map (inject, _, bij'), x ->
-        let y = inject x in
-        encode bij' y
-      | Switch (inject, _), x ->
-        let c, BranchTo (bij', y) = inject x in
-        Sink.write_char sink c;
-        encode bij' y
-    in encode bij x
-end
-
-module SexpDecode(Source : SOURCE) = struct
-  type source = Source.t
-
-  let decode ~bij source =
-    let rec cur () = Source.cur source
-    and junk () = Source.junk source
-    and eof () = Source.eof source
-    in
-    (* eat whitespace *)
-    let rec whitespace () =
-      if not (eof ()) then match cur () with
-        | ' ' | '\t' | '\n' -> junk (); whitespace ()
-        | _ -> ()
-    in
-    (* decode using the [bij] *)
-    let rec decode : type a. a bij -> a = fun bij ->
-      whitespace ();
-      match bij with
-      | Unit -> ()
-      | String -> decode_string (Buffer.create 5)
-      | Int -> decode_int 0
-      | Float ->
-        begin try float_of_string (decode_string (Buffer.create 3))
-        with Failure _ -> raise (DecodingError ("expected float"))
-        end
-      | Bool ->
-        begin match decode_string (Buffer.create 4) with
-        | "true" -> true
-        | "false" -> false
-        | s -> raise (DecodingError ("expected bool, got " ^ s))
-        end
-      | List bij' ->
-        decode_open ();
-        let l = decode_list bij' [] in
-        decode_close ();
-        l
-      | Many bij' ->
-        decode_open ();
-        let l = decode_list bij' [] in
-        decode_close ();
-        if l = [] then raise (DecodingError "expected non empty list") else l
-      | Opt bij' ->
-        decode_open ();
-        let l = decode_list bij' [] in
-        decode_close ();
-        begin match l with
-        | [] -> None
-        | [x] -> Some x
-        | _ ->  raise (DecodingError "expected option")
-        end
-      | Pair (bija, bijb) ->
-        decode_open ();
-        let a = decode bija in
-        let b = decode bijb in
-        decode_close ();
-        a, b
-      | Triple (bija, bijb, bijc) ->
-        decode_open ();
-        let a = decode bija in
-        let b = decode bijb in
-        let c = decode bijc in
-        decode_close ();
-        a, b, c
-      | Quad (bija, bijb, bijc, bijd) ->
-        decode_open ();
-        let a = decode bija in
-        let b = decode bijb in
-        let c = decode bijc in
-        let d = decode bijd in
-        decode_close ();
-        a, b, c, d
-      | Quint (bija, bijb, bijc, bijd, bije) ->
-        decode_open ();
-        let a = decode bija in
-        let b = decode bijb in
-        let c = decode bijc in
-        let d = decode bijd in
-        let e = decode bije in
-        decode_close ();
-        a, b, c, d, e 
-      | Guard (check, bij') ->
-        let x = decode bij' in
-        (if not (check x) then raise (DecodingError "check failed"));
-        x
-      | Map (_, extract, bij') ->
-        let x = decode bij' in
-        extract x
-      | Switch (_, extract) ->
-        let c = cur () in
-        let BranchFrom (bij', convert) = extract c in
-        junk ();   (* remove c *)
-        let y = decode bij' in
-        convert y  (* translate back *)
-    and decode_open : unit -> unit = fun () -> match cur () with
-      | '(' -> junk ()  (* done *)
-      | _ -> raise (DecodingError "expected '('")
-    and decode_close : unit -> unit = fun () ->
-      whitespace ();  (* on close, first eat whitespace *)
-      match cur () with
-      | ')' -> junk ()  (* done *)
-      | _ -> raise (DecodingError "expected ')'")
-    and decode_int : int -> int = fun i ->
-      if eof () then i
-      else match cur () with
-      | '-' when i = 0 -> junk (); ~- (decode_int 0)  (* negative *)
-      | c when Char.code c >= Char.code '0' && Char.code c <= Char.code '9' ->
-        junk ();
-        decode_int (i * 10 + (Char.code c - Char.code '0'))
-      | _ -> i
-    and decode_string : Buffer.t -> string = fun buf ->
-      if eof () then Buffer.contents buf
-      else match cur() with
-      | ' ' | '\t' | '\n' | ')' -> Buffer.contents buf
-      | '\\' -> junk (); Buffer.add_char buf (cur ()); junk (); decode_string buf
-      | c -> Buffer.add_char buf c; junk (); decode_string buf
-    and decode_list : type a. a t -> a list -> a list = fun bij l ->
-      whitespace ();
-      match cur() with
-      | ')' -> List.rev l  (* done *)
-      | _ ->
-        let x = decode bij in
-        decode_list bij (x :: l)
-    in
-    try
-      decode bij
-    with EOF ->
-      raise (DecodingError "unexpected EOF")
-end
-
-module SexpStr = struct
-  module SexpEncodeBuf = SexpEncode(SinkBuf)
-  module SexpDecodeString = SexpDecode(SourceStr)
-
-  let to_string ?(bufsize=64) ~bij x =
-    let b = Buffer.create bufsize in
-    SexpEncodeBuf.encode ~bij b x;
-    Buffer.contents b
+  let to_string ~bij x = B.to_string (encode ~bij x)
 
   let of_string ~bij s =
-    SexpDecodeString.decode ~bij (SourceStr.create s)
-end
+    let b = B.of_string s in
+    decode ~bij b
 
-module SexpChan = struct
-  module SexpEncodeChan = SexpEncode(SinkChan)
-  module SexpDecodeChan = SexpDecode(SourceChan)
+  (* TODO *)
+  let read ~bij ic = failwith "read: not implemented"
 
-  include SexpEncodeChan
-  include SexpDecodeChan
+  let write ~bij x oc = failwith "write: not implemented"
 end
diff --git a/bij.mli b/bij.mli
index fb6c1cad..6cc8ee83 100644
--- a/bij.mli
+++ b/bij.mli
@@ -25,26 +25,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 (** {1 Bijective Serializer/Deserializer} *)
 
-type 'a t = private
-  | Unit : unit t
-  | String : string t
-  | Int : int t
-  | Bool : bool t
-  | Float : float t
-  | List : 'a t -> 'a list t
-  | Many : 'a t -> 'a list t
-  | Opt : 'a t -> 'a option t
-  | Pair : 'a t * 'b t -> ('a * 'b) t
-  | Triple : 'a t * 'b t * 'c t -> ('a * 'b * 'c) t
-  | Quad : 'a t * 'b t * 'c t * 'd t -> ('a * 'b * 'c * 'd) t
-  | Quint : 'a t * 'b t * 'c t * 'd t * 'e t -> ('a * 'b * 'c * 'd * 'e) t
-  | Guard : ('a -> bool) * 'a t -> 'a t
-  | Map : ('a -> 'b) * ('b -> 'a) * 'b t -> 'a t
-  | Switch : ('a -> char * 'a inject_branch) * (char -> 'a extract_branch) -> 'a t
-and _ inject_branch =
-  | BranchTo : 'b t * 'b -> 'a inject_branch
-and _ extract_branch =
-  | BranchFrom : 'b t * ('b -> 'a) -> 'a extract_branch
+type 'a t
 
 (** {2 Bijection description} *)
 
@@ -66,100 +47,49 @@ val guard : ('a -> bool) -> 'a t -> 'a t
 
 val map : inject:('a -> 'b) -> extract:('b -> 'a) -> 'b t -> 'a t
 
-val switch : inject:('a -> char * 'a inject_branch) ->
-             extract:(char -> 'a extract_branch) -> 'a t
+type _ inject_branch =
+  | BranchTo : 'b t * 'b -> 'a inject_branch
+type _ extract_branch =
+  | BranchFrom : 'b t * ('b -> 'a) -> 'a extract_branch
+
+val switch : inject:('a -> string * 'a inject_branch) ->
+             extract:(string -> 'a extract_branch) -> 'a t
   (** Discriminates unions based on the next character.
-      [inject] is used to select a character, as well as mapping to another
+      [inject] must give a unique key for each branch, as well as mapping to another
       type (the argument of the algebraic constructor);
-      [extract] retrieves which type to parse based on the character. *)
+      [extract] retrieves which type to parse based on the key. *)
 
 (** {2 Helpers} *)
 
-val fix : ((unit -> 'a t) -> 'a t) -> 'a t
-  (** Helper for recursive encodings *)
+val fix : ('a t lazy_t -> 'a t) -> 'a t
+  (** Helper for recursive encodings. The parameter is the recursive bijection
+      itself. It must be lazy. *)
 
 val with_version : string -> 'a t -> 'a t
   (** Guards the values with a given version. Only values encoded with
       the same version will fit. *)
 
-val array_ : 'a t -> 'a array t
-val hashtbl : 'a t -> 'b t -> ('a, 'b) Hashtbl.t t
-
 (** {2 Exceptions} *)
 
-exception EOF
-
 exception EncodingError of string
-  (** Raised when decoding is impossible *)
+  (** Raised when encoding is impossible *)
 
 exception DecodingError of string
   (** Raised when decoding is impossible *)
 
-(** {2 Source of parsing} *)
+(** {2 Translations} *)
 
-module type SOURCE = sig
-  type t
+module TrBencode : sig
+  val encode : bij:'a t -> 'a -> Bencode.t
 
-  val eof : t -> bool
-    (** End of input reached? *)
+  val decode : bij:'a t -> Bencode.t -> 'a
 
-  val cur : t -> char
-    (** Current char *)
+  val to_string : bij:'a t -> 'a -> string
 
-  val junk : t -> unit
-    (** Discard current char *)
-end
-
-module SourceStr : sig
-  include SOURCE
-  val create : string -> t
-end
-
-module SourceStream : SOURCE with type t = char Stream.t
-
-module SourceChan : sig
-  include SOURCE 
-  val create : ?bufsize:int -> in_channel -> t
-end
-
-(** {2 Sink: Where to print} *)
-
-module type SINK = sig
-  type t
-  val write : t -> string -> int -> int -> unit  (* write substring [i..i+len] *)
-  val write_char : t -> char -> unit
-  val write_int : t -> int -> unit
-  val write_bool : t -> bool -> unit
-  val write_float : t -> float -> unit
-end
-
-module SinkBuf : SINK with type t = Buffer.t
-
-module SinkChan : SINK with type t = out_channel
-
-(** {2 Encoding/decoding} *)
-
-module type ENCODE = sig
-  type sink
-  val encode : bij:'a t -> sink -> 'a -> unit
-end
-
-module type DECODE = sig
-  type source
-  val decode : bij:'a t -> source -> 'a
-end
-
-module SexpEncode(Sink : SINK) : ENCODE with type sink = Sink.t
-module SexpDecode(Source : SOURCE) : DECODE with type source = Source.t
-
-(** Specific instance for encoding to/from strings *)
-module SexpStr : sig
-  val to_string : ?bufsize:int -> bij:'a t -> 'a -> string
   val of_string : bij:'a t -> string -> 'a
-end 
 
-(** Specific instance for encoding to/from channels *)
-module SexpChan : sig
-  include ENCODE with type sink = SinkChan.t
-  include DECODE with type source = SourceChan.t
+  val read : bij:'a t -> in_channel -> 'a
+
+  val write : bij:'a t -> 'a t -> out_channel -> unit
 end
+
diff --git a/tests/test_bij.ml b/tests/test_bij.ml
index 55b5c18a..8b94bac6 100644
--- a/tests/test_bij.ml
+++ b/tests/test_bij.ml
@@ -1,18 +1,6 @@
 
 open OUnit
 
-open Bij
-
-let test_int2 () =
-  let bij = pair int_ int_ in
-  let s = SexpStr.to_string bij (1,2) in
-  OUnit.assert_equal ~printer:(fun x -> x) "(1 2)" s
-
-let test_escape () =
-  let bij = pair int_ (pair string_ string_) in
-  let s = SexpStr.to_string bij (1,("foo()","bar\n hello")) in
-  OUnit.assert_equal ~printer:(fun x -> x) "(1 (foo(\\) bar\\n\\ hello))" s
-
 let pp_int_list l =
   let b = Buffer.create 4 in
   Format.fprintf (Format.formatter_of_buffer b) "%a@?"
@@ -20,10 +8,10 @@ let pp_int_list l =
   Buffer.contents b
 
 let test_intlist n () =
-  let bij = list_ int_ in
+  let bij = Bij.(list_ int_) in
   let l = Sequence.to_list (Sequence.int_range ~start:0 ~stop:n) in
-  let s = SexpStr.to_string ~bij l in
-  let l' = SexpStr.of_string ~bij s in
+  let s = Bij.TrBencode.to_string ~bij l in
+  let l' = Bij.TrBencode.of_string ~bij s in
   OUnit.assert_equal ~printer:pp_int_list l l'
 
 type term =
@@ -32,26 +20,27 @@ type term =
   | App of term list
 
 let bij_term =
-  let bij = fix
+  let bij = Bij.(fix
     (fun bij ->
     switch
     ~inject:(function
-      | Const s -> 'c', BranchTo (string_, s)
-      | Int i -> 'i', BranchTo (int_, i)
-      | App l -> 'a', BranchTo (list_ (bij ()), l))
+      | Const s -> "const", BranchTo (string_, s)
+      | Int i -> "int", BranchTo (int_, i)
+      | App l -> "app", BranchTo (list_ (Lazy.force bij), l))
     ~extract:(function
-      | 'c' -> BranchFrom (string_, fun x -> Const x)
-      | 'i' -> BranchFrom (int_, fun x -> Int x)
-      | 'a' -> BranchFrom (list_ (bij ()), fun l -> App l)
+      | "const" -> BranchFrom (string_, fun x -> Const x)
+      | "int" -> BranchFrom (int_, fun x -> Int x)
+      | "app" -> BranchFrom (list_ (Lazy.force bij), fun l -> App l)
       | _ -> raise (DecodingError "unexpected case switch")))
+    )
   in
   bij
 
 let test_rec () =
   let t = App [Const "foo"; App [Const "bar"; Int 1; Int 2]; Int 3; Const "hello"] in
-  let s = SexpStr.to_string ~bij:bij_term t in
+  let s = Bij.TrBencode.to_string ~bij:bij_term t in
   (* Printf.printf "to: %s\n" s; *)
-  let t' = SexpStr.of_string ~bij:bij_term s in
+  let t' = Bij.TrBencode.of_string ~bij:bij_term s in
   OUnit.assert_equal t t'
 
 let random_str len =
@@ -75,28 +64,26 @@ let rec random_term depth =
 let test_term_random ?(depth=5) n () =
   for i = 0 to n - 1 do
     let t = random_term depth in
-    let s = SexpStr.to_string ~bij:bij_term t in
-    let t' = SexpStr.of_string ~bij:bij_term s in
+    let s = Bij.TrBencode.to_string ~bij:bij_term t in
+    let t' = Bij.TrBencode.of_string ~bij:bij_term s in
     OUnit.assert_equal t t'
   done
 
 let test_complicated () =
-  let bij = triple int_ (pair bool_ (many float_))
-    (map ~inject:(fun (a,b) -> (b,a)) ~extract:(fun (b,a) -> a,b) (pair int_ bool_)) in
+  let bij = Bij.(triple int_ (pair bool_ (many float_))
+    (map ~inject:(fun (a,b) -> (b,a)) ~extract:(fun (b,a) -> a,b) (pair int_ bool_))) in
   let x = (1, (true, [1.; 2.; 3.]), (false, 42)) in
-  let s = SexpStr.to_string ~bij x in
-  let x' = SexpStr.of_string ~bij s in
+  let s = Bij.TrBencode.to_string ~bij x in
+  let x' = Bij.TrBencode.of_string ~bij s in
   OUnit.assert_equal x x'
 
 let suite =
   "test_bij" >:::
-    [ "test_int2" >:: test_int2;
-      "test_escape" >:: test_escape;
-      "test_intlist10" >:: test_intlist 10;
-      "test_intlist100" >:: test_intlist 100;
-      "test_intlist10_000" >:: test_intlist 10_000;
-      "test_rec" >:: test_rec;
-      "test_term_random100" >:: test_term_random 100;
-      "test_term_random100_depth10" >:: test_term_random ~depth:10 100;
-      "test_complicated" >:: test_complicated;
+    [ "test_intlist10" >:: test_intlist 10
+    ; "test_intlist100" >:: test_intlist 100
+    ; "test_intlist10_000" >:: test_intlist 10_000
+    ; "test_rec" >:: test_rec
+    ; "test_term_random100" >:: test_term_random 100
+    ; "test_term_random100_depth10" >:: test_term_random ~depth:10 100
+    ; "test_complicated" >:: test_complicated
     ]