sx: step 13 — buffer primitives + buffer-based inspect

Added short aliases make-buffer / buffer? / buffer-append! / buffer->string / buffer-length on both OCaml and JS hosts, sharing the existing StringBuffer value type. buffer-append! auto-coerces non-strings via inspect. Rewrote the OCaml host inspect function to walk a single shared Buffer.t instead of allocating O(n) intermediate strings via String.concat at every recursion level. inspect underlies sx-serialize and error-path formatting, so this benefits the tightest serialization paths. Median improvements (bin/bench_inspect.exe, best-of-3 of 9-run min): tree-d8 (75KB): 5.31ms -> 1.30ms (-76%) tree-d10 (679KB): 81.89ms -> 16.02ms (-80%) dict-1000: 0.80ms -> 0.31ms (-61%) list-2000: 0.74ms -> 0.33ms (-55%) Tests: OCaml 4545 -> 4550. JS 2591 -> 2596. Zero regressions. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-07 02:16:59 +00:00
parent c48911e591
commit 0e022ab670
9 changed files with 303 additions and 67 deletions
--- a/hosts/javascript/platform.py
+++ b/hosts/javascript/platform.py
@@ -1476,6 +1476,22 @@ PRIMITIVES_JS_MODULES: dict[str, str] = {
  };
  PRIMITIVES["string-buffer->string"] = function(buf) { return buf.parts.join(""); };
  PRIMITIVES["string-buffer-length"] = function(buf) { return buf.len; };
+
+  // Short aliases — terser names; append accepts any value
+  PRIMITIVES["make-buffer"] = function() { return new SxStringBuffer(); };
+  PRIMITIVES["buffer?"] = function(x) { return x instanceof SxStringBuffer; };
+  PRIMITIVES["buffer-append!"] = function(buf, v) {
+    var s;
+    if (v === null || v === undefined || v === NIL) s = "";
+    else if (typeof v === "string") s = v;
+    else if (typeof v === "boolean") s = v ? "true" : "false";
+    else if (typeof v === "number") s = String(v);
+    else if (v && typeof v === "object" && typeof v.name === "string" && v.constructor && v.constructor.name === "Symbol") s = v.name;
+    else s = (typeof inspect === "function") ? inspect(v) : String(v);
+    buf.parts.push(s); buf.len += s.length; return NIL;
+  };
+  PRIMITIVES["buffer->string"] = function(buf) { return buf.parts.join(""); };
+  PRIMITIVES["buffer-length"] = function(buf) { return buf.len; };
 ''',

    "stdlib.format": '''
--- a/hosts/ocaml/bin/bench_inspect.ml
+++ b/hosts/ocaml/bin/bench_inspect.ml
@@ -0,0 +1,46 @@
+(* Benchmark inspect on representative SX values.
+   Takes min of 9 runs of n iterations to dampen GC noise. *)
+open Sx_types
+
+let rec make_tree d =
+  if d = 0 then String "leaf"
+  else List [String "node"; make_tree (d - 1); make_tree (d - 1); make_tree (d - 1)]
+
+let bench_min label f n runs =
+  let times = ref [] in
+  for _ = 1 to runs do
+    Gc.compact ();
+    let t0 = Unix.gettimeofday () in
+    for _ = 1 to n do ignore (f ()) done;
+    let t1 = Unix.gettimeofday () in
+    times := (t1 -. t0) :: !times
+  done;
+  let sorted = List.sort compare !times in
+  let min_t = List.nth sorted 0 in
+  let median = List.nth sorted (runs / 2) in
+  Printf.printf "  %-30s  min=%6.2fms  median=%6.2fms  (n=%d * %d runs)\n%!"
+    label (min_t *. 1000.0 /. float_of_int n)
+    (median *. 1000.0 /. float_of_int n) n runs
+
+let () =
+  let tree8 = make_tree 8 in
+  let s = inspect tree8 in
+  Printf.printf "tree-d8 inspect len=%d\n%!" (String.length s);
+  bench_min "inspect tree-d8" (fun () -> inspect tree8) 50 9;
+
+  let tree10 = make_tree 10 in
+  let s = inspect tree10 in
+  Printf.printf "tree-d10 inspect len=%d\n%!" (String.length s);
+  bench_min "inspect tree-d10" (fun () -> inspect tree10) 5 9;
+
+  let dict_xs = make_dict () in
+  for i = 0 to 999 do
+    Hashtbl.replace dict_xs (string_of_int i) (Integer i)
+  done;
+  let d = Dict dict_xs in
+  bench_min "inspect dict-1000" (fun () -> inspect d) 100 9;
+
+  let xs = ref [] in
+  for i = 0 to 1999 do xs := Integer i :: !xs done;
+  let lst = List !xs in
+  bench_min "inspect list-2000" (fun () -> inspect lst) 200 9
--- a/hosts/ocaml/bin/dune
+++ b/hosts/ocaml/bin/dune
@@ -1,5 +1,5 @@
 (executables
- (names run_tests debug_set sx_server integration_tests bench_cek)
+ (names run_tests debug_set sx_server integration_tests bench_cek bench_inspect)
 (libraries sx unix threads.posix otfm yojson))

 (executable
--- a/hosts/ocaml/lib/sx_primitives.ml
+++ b/hosts/ocaml/lib/sx_primitives.ml
@@ -1607,6 +1607,32 @@ let () =
    match args with [StringBuffer buf] -> Integer (Buffer.length buf)
    | _ -> raise (Eval_error "string-buffer-length: expected (buffer)"));

+  (* Short aliases — same StringBuffer value, terser names for hot paths.
+     Append accepts any value: strings pass through, others get inspected/coerced. *)
+  register "make-buffer" (fun _ -> StringBuffer (Buffer.create 64));
+  register "buffer?" (fun args ->
+    match args with [StringBuffer _] -> Bool true | [_] -> Bool false
+    | _ -> raise (Eval_error "buffer?: expected 1 arg"));
+  register "buffer-append!" (fun args ->
+    match args with
+    | [StringBuffer buf; String s] -> Buffer.add_string buf s; Nil
+    | [StringBuffer buf; Integer n] -> Buffer.add_string buf (string_of_int n); Nil
+    | [StringBuffer buf; Number n] -> Buffer.add_string buf (Sx_types.format_number n); Nil
+    | [StringBuffer buf; Symbol s] -> Buffer.add_string buf s; Nil
+    | [StringBuffer buf; Char n] ->
+      Buffer.add_utf_8_uchar buf (Uchar.of_int n); Nil
+    | [StringBuffer buf; Nil] -> Buffer.add_string buf ""; Nil
+    | [StringBuffer buf; Bool true] -> Buffer.add_string buf "true"; Nil
+    | [StringBuffer buf; Bool false] -> Buffer.add_string buf "false"; Nil
+    | [StringBuffer buf; v] -> Buffer.add_string buf (inspect v); Nil
+    | _ -> raise (Eval_error "buffer-append!: expected (buffer value)"));
+  register "buffer->string" (fun args ->
+    match args with [StringBuffer buf] -> String (Buffer.contents buf)
+    | _ -> raise (Eval_error "buffer->string: expected (buffer)"));
+  register "buffer-length" (fun args ->
+    match args with [StringBuffer buf] -> Integer (Buffer.length buf)
+    | _ -> raise (Eval_error "buffer-length: expected (buffer)"));
+
  (* Capability-based sandboxing — gate IO operations *)
  let cap_stack : string list ref = ref [] in
  register "with-capabilities" (fun args ->
--- a/hosts/ocaml/lib/sx_types.ml
+++ b/hosts/ocaml/lib/sx_types.ml
@@ -817,14 +817,15 @@ let dict_vals (d : dict) =

 (** {1 Value display} *)

-let rec inspect = function
-  | Nil -> "nil"
-  | Bool true -> "true"
-  | Bool false -> "false"
-  | Integer n -> string_of_int n
-  | Number n -> format_number n
+(* Single shared buffer for the entire inspect recursion — eliminates
+   the per-level [String.concat (List.map inspect ...)] allocation. *)
+let rec inspect_into buf = function
+  | Nil -> Buffer.add_string buf "nil"
+  | Bool true -> Buffer.add_string buf "true"
+  | Bool false -> Buffer.add_string buf "false"
+  | Integer n -> Buffer.add_string buf (string_of_int n)
+  | Number n -> Buffer.add_string buf (format_number n)
  | String s ->
-    let buf = Buffer.create (String.length s + 2) in
    Buffer.add_char buf '"';
    String.iter (function
      | '"'  -> Buffer.add_string buf "\\\""
@@ -833,72 +834,129 @@ let rec inspect = function
      | '\r' -> Buffer.add_string buf "\\r"
      | '\t' -> Buffer.add_string buf "\\t"
      | c    -> Buffer.add_char buf c) s;
-    Buffer.add_char buf '"';
-    Buffer.contents buf
-  | Symbol s -> s
-  | Keyword k -> ":" ^ k
+    Buffer.add_char buf '"'
+  | Symbol s -> Buffer.add_string buf s
+  | Keyword k -> Buffer.add_char buf ':'; Buffer.add_string buf k
  | List items | ListRef { contents = items } ->
-    "(" ^ String.concat " " (List.map inspect items) ^ ")"
+    Buffer.add_char buf '(';
+    (match items with
+     | [] -> ()
+     | x :: rest ->
+       inspect_into buf x;
+       List.iter (fun v -> Buffer.add_char buf ' '; inspect_into buf v) rest);
+    Buffer.add_char buf ')'
  | Dict d ->
-    let pairs = Hashtbl.fold (fun k v acc ->
-      (Printf.sprintf ":%s %s" k (inspect v)) :: acc) d [] in
-    "{" ^ String.concat " " pairs ^ "}"
+    Buffer.add_char buf '{';
+    let first = ref true in
+    Hashtbl.iter (fun k v ->
+      if !first then first := false else Buffer.add_char buf ' ';
+      Buffer.add_char buf ':'; Buffer.add_string buf k;
+      Buffer.add_char buf ' '; inspect_into buf v) d;
+    Buffer.add_char buf '}'
  | Lambda l ->
    let tag = match l.l_name with Some n -> n | None -> "lambda" in
-    Printf.sprintf "<%s(%s)>" tag (String.concat ", " l.l_params)
+    Buffer.add_char buf '<'; Buffer.add_string buf tag;
+    Buffer.add_char buf '('; Buffer.add_string buf (String.concat ", " l.l_params);
+    Buffer.add_string buf ")>"
  | Component c ->
-    Printf.sprintf "<Component ~%s(%s)>" c.c_name (String.concat ", " c.c_params)
+    Buffer.add_string buf "<Component ~"; Buffer.add_string buf c.c_name;
+    Buffer.add_char buf '('; Buffer.add_string buf (String.concat ", " c.c_params);
+    Buffer.add_string buf ")>"
  | Island i ->
-    Printf.sprintf "<Island ~%s(%s)>" i.i_name (String.concat ", " i.i_params)
+    Buffer.add_string buf "<Island ~"; Buffer.add_string buf i.i_name;
+    Buffer.add_char buf '('; Buffer.add_string buf (String.concat ", " i.i_params);
+    Buffer.add_string buf ")>"
  | Macro m ->
    let tag = match m.m_name with Some n -> n | None -> "macro" in
-    Printf.sprintf "<%s(%s)>" tag (String.concat ", " m.m_params)
-  | Thunk _ -> "<thunk>"
-  | Continuation (_, _) -> "<continuation>"
-  | CallccContinuation (_, _) -> "<callcc-continuation>"
-  | NativeFn (name, _) -> Printf.sprintf "<native:%s>" name
-  | Signal _ -> "<signal>"
-  | RawHTML s -> Printf.sprintf "\"<raw-html:%d>\"" (String.length s)
-  | Spread _ -> "<spread>"
-  | SxExpr s -> Printf.sprintf "\"<sx-expr:%d>\"" (String.length s)
-  | Env _ -> "<env>"
-  | CekState _ -> "<cek-state>"
-  | CekFrame f -> Printf.sprintf "<frame:%s>" f.cf_type
-  | VmClosure cl -> Printf.sprintf "<vm:%s>" (match cl.vm_name with Some n -> n | None -> "anon")
+    Buffer.add_char buf '<'; Buffer.add_string buf tag;
+    Buffer.add_char buf '('; Buffer.add_string buf (String.concat ", " m.m_params);
+    Buffer.add_string buf ")>"
+  | Thunk _ -> Buffer.add_string buf "<thunk>"
+  | Continuation (_, _) -> Buffer.add_string buf "<continuation>"
+  | CallccContinuation (_, _) -> Buffer.add_string buf "<callcc-continuation>"
+  | NativeFn (name, _) ->
+    Buffer.add_string buf "<native:"; Buffer.add_string buf name; Buffer.add_char buf '>'
+  | Signal _ -> Buffer.add_string buf "<signal>"
+  | RawHTML s ->
+    Buffer.add_string buf "\"<raw-html:";
+    Buffer.add_string buf (string_of_int (String.length s));
+    Buffer.add_string buf ">\""
+  | Spread _ -> Buffer.add_string buf "<spread>"
+  | SxExpr s ->
+    Buffer.add_string buf "\"<sx-expr:";
+    Buffer.add_string buf (string_of_int (String.length s));
+    Buffer.add_string buf ">\""
+  | Env _ -> Buffer.add_string buf "<env>"
+  | CekState _ -> Buffer.add_string buf "<cek-state>"
+  | CekFrame f ->
+    Buffer.add_string buf "<frame:"; Buffer.add_string buf f.cf_type; Buffer.add_char buf '>'
+  | VmClosure cl ->
+    Buffer.add_string buf "<vm:";
+    Buffer.add_string buf (match cl.vm_name with Some n -> n | None -> "anon");
+    Buffer.add_char buf '>'
  | Record r ->
-    let fields = Array.to_list (Array.mapi (fun i v ->
-      Printf.sprintf "%s=%s" r.r_type.rt_fields.(i) (inspect v)
-    ) r.r_fields) in
-    Printf.sprintf "<record:%s %s>" r.r_type.rt_name (String.concat " " fields)
-  | Parameter p -> Printf.sprintf "<parameter:%s>" p.pm_uid
+    Buffer.add_string buf "<record:"; Buffer.add_string buf r.r_type.rt_name;
+    Array.iteri (fun i v ->
+      Buffer.add_char buf ' ';
+      Buffer.add_string buf r.r_type.rt_fields.(i);
+      Buffer.add_char buf '=';
+      inspect_into buf v) r.r_fields;
+    Buffer.add_char buf '>'
+  | Parameter p ->
+    Buffer.add_string buf "<parameter:"; Buffer.add_string buf p.pm_uid; Buffer.add_char buf '>'
  | Vector arr ->
-    let elts = Array.to_list (Array.map inspect arr) in
-    Printf.sprintf "#(%s)" (String.concat " " elts)
-  | VmFrame f -> Printf.sprintf "<vm-frame:ip=%d base=%d>" f.vf_ip f.vf_base
-  | VmMachine m -> Printf.sprintf "<vm-machine:sp=%d frames=%d>" m.vm_sp (List.length m.vm_frames)
-  | StringBuffer buf -> Printf.sprintf "<string-buffer:%d>" (Buffer.length buf)
-  | HashTable ht -> Printf.sprintf "<hash-table:%d>" (Hashtbl.length ht)
+    Buffer.add_string buf "#(";
+    Array.iteri (fun i v ->
+      if i > 0 then Buffer.add_char buf ' ';
+      inspect_into buf v) arr;
+    Buffer.add_char buf ')'
+  | VmFrame f ->
+    Buffer.add_string buf (Printf.sprintf "<vm-frame:ip=%d base=%d>" f.vf_ip f.vf_base)
+  | VmMachine m ->
+    Buffer.add_string buf (Printf.sprintf "<vm-machine:sp=%d frames=%d>" m.vm_sp (List.length m.vm_frames))
+  | StringBuffer b ->
+    Buffer.add_string buf (Printf.sprintf "<string-buffer:%d>" (Buffer.length b))
+  | HashTable ht ->
+    Buffer.add_string buf (Printf.sprintf "<hash-table:%d>" (Hashtbl.length ht))
  | Char n ->
-    let name = match n with
-      | 32 -> "space" | 10 -> "newline" | 9 -> "tab"
-      | 13 -> "return" | 0 -> "nul" | 27 -> "escape"
-      | 127 -> "delete" | 8 -> "backspace"
-      | _ -> let buf = Buffer.create 1 in
-             Buffer.add_utf_8_uchar buf (Uchar.of_int n);
-             Buffer.contents buf
-    in "#\\" ^ name
-  | Eof -> "#!eof"
+    Buffer.add_string buf "#\\";
+    (match n with
+     | 32 -> Buffer.add_string buf "space"
+     | 10 -> Buffer.add_string buf "newline"
+     | 9 -> Buffer.add_string buf "tab"
+     | 13 -> Buffer.add_string buf "return"
+     | 0 -> Buffer.add_string buf "nul"
+     | 27 -> Buffer.add_string buf "escape"
+     | 127 -> Buffer.add_string buf "delete"
+     | 8 -> Buffer.add_string buf "backspace"
+     | _ -> Buffer.add_utf_8_uchar buf (Uchar.of_int n))
+  | Eof -> Buffer.add_string buf "#!eof"
  | Port { sp_kind = PortInput (_, pos); sp_closed } ->
-    Printf.sprintf "<input-port:pos=%d%s>" !pos (if sp_closed then ":closed" else "")
-  | Port { sp_kind = PortOutput buf; sp_closed } ->
-    Printf.sprintf "<output-port:len=%d%s>" (Buffer.length buf) (if sp_closed then ":closed" else "")
-  | Rational (n, d) -> Printf.sprintf "%d/%d" n d
-  | SxSet ht -> Printf.sprintf "<set:%d>" (Hashtbl.length ht)
-  | SxRegexp (src, flags, _) -> Printf.sprintf "#/%s/%s" src flags
-  | SxBytevector b -> Printf.sprintf "#u8(%s)" (String.concat " " (List.init (Bytes.length b) (fun i -> string_of_int (Char.code (Bytes.get b i)))))
+    Buffer.add_string buf (Printf.sprintf "<input-port:pos=%d%s>" !pos (if sp_closed then ":closed" else ""))
+  | Port { sp_kind = PortOutput b; sp_closed } ->
+    Buffer.add_string buf (Printf.sprintf "<output-port:len=%d%s>" (Buffer.length b) (if sp_closed then ":closed" else ""))
+  | Rational (n, d) ->
+    Buffer.add_string buf (string_of_int n); Buffer.add_char buf '/';
+    Buffer.add_string buf (string_of_int d)
+  | SxSet ht ->
+    Buffer.add_string buf (Printf.sprintf "<set:%d>" (Hashtbl.length ht))
+  | SxRegexp (src, flags, _) ->
+    Buffer.add_string buf "#/"; Buffer.add_string buf src;
+    Buffer.add_char buf '/'; Buffer.add_string buf flags
+  | SxBytevector b ->
+    Buffer.add_string buf "#u8(";
+    let n = Bytes.length b in
+    for i = 0 to n - 1 do
+      if i > 0 then Buffer.add_char buf ' ';
+      Buffer.add_string buf (string_of_int (Char.code (Bytes.get b i)))
+    done;
+    Buffer.add_char buf ')'
  | AdtValue a ->
-    if Array.length a.av_fields = 0 then
-      Printf.sprintf "(%s)" a.av_ctor
-    else
-      let parts = Array.to_list (Array.map inspect a.av_fields) in
-      Printf.sprintf "(%s %s)" a.av_ctor (String.concat " " parts)
+    Buffer.add_char buf '('; Buffer.add_string buf a.av_ctor;
+    Array.iter (fun v -> Buffer.add_char buf ' '; inspect_into buf v) a.av_fields;
+    Buffer.add_char buf ')'
+
+let inspect v =
+  let buf = Buffer.create 64 in
+  inspect_into buf v;
+  Buffer.contents buf