ocaml: numeric tower — Integer/Number distinction + float contagion

Add `Integer of int` to sx_types.ml alongside `Number of float`. Parser
produces Integer for whole-number literals. Arithmetic primitives apply
float contagion (int op int → Integer, int op float → Number). Division
always returns Number. Rounding (floor/truncate/round) returns Integer.
Predicates: integer?, float?, exact?, inexact?, exact->inexact,
inexact->exact. run_tests.ml updated for json_of_value, value_of_json,
identical?, random-int mock, DOM accessors, and parser pattern matches.
New spec/tests/test-numeric-tower.sx — 92 tests, all pass (394 unchanged).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

hosts/ocaml/bin/run_tests.ml

@@ -37,7 +37,10 @@ let rec deep_equal a b =
   match a, b with
   | Nil, Nil -> true
   | Bool a, Bool b -> a = b
+  | Integer a, Integer b -> a = b
   | Number a, Number b -> a = b
+  | Integer a, Number b -> float_of_int a = b
+  | Number a, Integer b -> a = float_of_int b
   | String a, String b -> a = b
   | Symbol a, Symbol b -> a = b
   | Keyword a, Keyword b -> a = b
@@ -226,7 +229,7 @@ let make_test_env () =
     | [String s] ->
       let parsed = Sx_parser.parse_all s in
       (match parsed with
-       | [List (Symbol "sxbc" :: Number _ :: payload :: _)] -> payload
+       | [List (Symbol "sxbc" :: (Number _ | Integer _) :: payload :: _)] -> payload
        | _ -> raise (Eval_error "bytecode-deserialize: invalid sxbc format"))
     | _ -> raise (Eval_error "bytecode-deserialize: expected string"));
 
@@ -240,7 +243,7 @@ let make_test_env () =
     | [String s] ->
       let parsed = Sx_parser.parse_all s in
       (match parsed with
-       | [List (Symbol "cek-state" :: Number _ :: payload :: _)] -> payload
+       | [List (Symbol "cek-state" :: (Number _ | Integer _) :: payload :: _)] -> payload
        | _ -> raise (Eval_error "cek-deserialize: invalid cek-state format"))
     | _ -> raise (Eval_error "cek-deserialize: expected string"));
 
@@ -320,7 +323,10 @@ let make_test_env () =
   bind "identical?" (fun args ->
     match args with
     | [a; b] -> Bool (match a, b with
+      | Integer x, Integer y -> x = y
       | Number x, Number y -> x = y
+      | Integer x, Number y -> float_of_int x = y
+      | Number x, Integer y -> x = float_of_int y
       | String x, String y -> x = y
       | Bool x, Bool y -> x = y
       | Nil, Nil -> true
@@ -366,11 +372,15 @@ let make_test_env () =
 
   bind "append!" (fun args ->
     match args with
-    | [ListRef r; v; Number n] when int_of_float n = 0 ->
+    | [ListRef r; v; (Number n)] when int_of_float n = 0 ->
       r := v :: !r; ListRef r  (* prepend *)
+    | [ListRef r; v; (Integer 0)] ->
+      r := v :: !r; ListRef r  (* prepend Integer index *)
     | [ListRef r; v] -> r := !r @ [v]; ListRef r  (* append in place *)
-    | [List items; v; Number n] when int_of_float n = 0 ->
+    | [List items; v; (Number n)] when int_of_float n = 0 ->
       List (v :: items)  (* immutable prepend *)
+    | [List items; v; (Integer 0)] ->
+      List (v :: items)  (* immutable prepend Integer index *)
     | [List items; v] -> List (items @ [v])  (* immutable fallback *)
     | _ -> raise (Eval_error "append!: expected list and value"));
 
@@ -546,7 +556,10 @@ let make_test_env () =
   bind "batch-begin!" (fun _args -> Sx_ref.batch_begin_b ());
   bind "batch-end!" (fun _args -> Sx_ref.batch_end_b ());
   bind "now-ms" (fun _args -> Number 1000.0);
-  bind "random-int" (fun args -> match args with [Number lo; _] -> Number lo | _ -> Number 0.0);
+  bind "random-int" (fun args -> match args with
+    | [Number lo; _] -> Number lo
+    | [Integer lo; _] -> Integer lo
+    | _ -> Integer 0);
   bind "try-rerender-page" (fun _args -> Nil);
   bind "collect!" (fun args ->
     match args with
@@ -1142,18 +1155,20 @@ let run_foundation_tests () =
   in
 
   Printf.printf "Suite: parser\n";
-  assert_eq "number" (Number 42.0) (List.hd (parse_all "42"));
+  assert_eq "number" (Integer 42) (List.hd (parse_all "42"));
   assert_eq "string" (String "hello") (List.hd (parse_all "\"hello\""));
   assert_eq "bool true" (Bool true) (List.hd (parse_all "true"));
   assert_eq "nil" Nil (List.hd (parse_all "nil"));
   assert_eq "keyword" (Keyword "class") (List.hd (parse_all ":class"));
   assert_eq "symbol" (Symbol "foo") (List.hd (parse_all "foo"));
-  assert_eq "list" (List [Symbol "+"; Number 1.0; Number 2.0]) (List.hd (parse_all "(+ 1 2)"));
+  assert_eq "list" (List [Symbol "+"; Integer 1; Integer 2]) (List.hd (parse_all "(+ 1 2)"));
   (match List.hd (parse_all "(div :class \"card\" (p \"hi\"))") with
    | List [Symbol "div"; Keyword "class"; String "card"; List [Symbol "p"; String "hi"]] ->
      incr pass_count; Printf.printf "  PASS: nested list\n"
    | v -> incr fail_count; Printf.printf "  FAIL: nested list — got %s\n" (Sx_types.inspect v));
   (match List.hd (parse_all "'(1 2 3)") with
+   | List [Symbol "quote"; List [Integer 1; Integer 2; Integer 3]] ->
+     incr pass_count; Printf.printf "  PASS: quote sugar\n"
    | List [Symbol "quote"; List [Number 1.0; Number 2.0; Number 3.0]] ->
      incr pass_count; Printf.printf "  PASS: quote sugar\n"
    | v -> incr fail_count; Printf.printf "  FAIL: quote sugar — got %s\n" (Sx_types.inspect v));
@@ -1161,7 +1176,7 @@ let run_foundation_tests () =
    | Dict d when dict_has d "a" && dict_has d "b" ->
      incr pass_count; Printf.printf "  PASS: dict literal\n"
    | v -> incr fail_count; Printf.printf "  FAIL: dict literal — got %s\n" (Sx_types.inspect v));
-  assert_eq "comment" (Number 42.0) (List.hd (parse_all ";; comment\n42"));
+  assert_eq "comment" (Integer 42) (List.hd (parse_all ";; comment\n42"));
   assert_eq "string escape" (String "hello\nworld") (List.hd (parse_all "\"hello\\nworld\""));
   assert_eq "multiple exprs" (Number 2.0) (Number (float_of_int (List.length (parse_all "(1 2 3) (4 5)"))));
 
@@ -1978,6 +1993,10 @@ let run_spec_tests env test_files =
       (match Hashtbl.find_opt d "children" with
        | Some (List l) when i >= 0 && i < List.length l -> List.nth l i
        | _ -> (match Hashtbl.find_opt d (string_of_int i) with Some v -> v | None -> Nil))
+    | [Dict d; Integer n] ->
+      (match Hashtbl.find_opt d "children" with
+       | Some (List l) when n >= 0 && n < List.length l -> List.nth l n
+       | _ -> (match Hashtbl.find_opt d (string_of_int n) with Some v -> v | None -> Nil))
     | _ -> Nil);
 
   (* Stringify a value for DOM string properties *)
@@ -2052,8 +2071,8 @@ let run_spec_tests env test_files =
          Hashtbl.replace d "childNodes" (List [])
        | _ -> ());
       stored
-    | [ListRef r; Number n; value] ->
+    | [ListRef r; idx_v; value] when (match idx_v with Number _ | Integer _ -> true | _ -> false) ->
-      let idx = int_of_float n in
+      let idx = match idx_v with Number n -> int_of_float n | Integer n -> n | _ -> 0 in
       let lst = !r in
       if idx >= 0 && idx < List.length lst then
         r := List.mapi (fun i v -> if i = idx then value else v) lst
@@ -2190,7 +2209,7 @@ let run_spec_tests env test_files =
             | [String name; value] ->
               let attrs = match Hashtbl.find_opt d "attributes" with Some (Dict a) -> a | _ ->
                 let a = Hashtbl.create 4 in Hashtbl.replace d "attributes" (Dict a); a in
-              let sv = match value with String s -> s | Number n ->
+              let sv = match value with String s -> s | Integer n -> string_of_int n | Number n ->
                 let i = int_of_float n in if float_of_int i = n then string_of_int i
                 else string_of_float n | _ -> Sx_types.inspect value in
               Hashtbl.replace attrs name (String sv);
@@ -2632,6 +2651,7 @@ let run_spec_tests env test_files =
   let rec json_of_value = function
     | Nil -> `Null
     | Bool b -> `Bool b
+    | Integer n -> `Int n
     | Number n ->
       if Float.is_integer n && Float.abs n < 1e16
       then `Int (int_of_float n) else `Float n
@@ -2647,8 +2667,8 @@ let run_spec_tests env test_files =
   let rec value_of_json = function
     | `Null -> Nil
     | `Bool b -> Bool b
-    | `Int i -> Number (float_of_int i)
+    | `Int i -> Integer i
-    | `Intlit s -> (try Number (float_of_string s) with _ -> String s)
+    | `Intlit s -> (try Integer (int_of_string s) with _ -> try Number (float_of_string s) with _ -> String s)
     | `Float f -> Number f
     | `String s -> String s
     | `List xs -> List (List.map value_of_json xs)

hosts/ocaml/lib/sx_parser.ml

@@ -90,9 +90,21 @@ let read_symbol s =
   String.sub s.src start (s.pos - start)
 
 let try_number str =
-  match float_of_string_opt str with
+  (* Integers (no '.' or 'e'/'E') → exact Integer; floats → inexact Number *)
-  | Some n -> Some (Number n)
+  let has_dec = String.contains str '.' in
-  | None -> None
+  let has_exp = String.contains str 'e' || String.contains str 'E' in
+  if has_dec || has_exp then
+    match float_of_string_opt str with
+    | Some n -> Some (Number n)
+    | None -> None
+  else
+    match int_of_string_opt str with
+    | Some n -> Some (Integer n)
+    | None ->
+      (* handles "nan", "inf", "-inf" *)
+      match float_of_string_opt str with
+      | Some n -> Some (Number n)
+      | None -> None
 
 let rec read_value s : value =
   skip_whitespace_and_comments s;

hosts/ocaml/lib/sx_primitives.ml

@@ -51,7 +51,15 @@ let get_primitive name =
 (* Trampoline hook — set by sx_ref after initialization to break circular dep *)
 let trampoline_hook : (value -> value) ref = ref (fun v -> v)
 
+let as_int = function
+  | Integer n -> n
+  | Number n -> int_of_float n
+  | v -> raise (Eval_error ("Expected number, got " ^ type_of v))
+
+let all_ints = List.for_all (function Integer _ -> true | _ -> false)
+
 let rec as_number = function
+  | Integer n -> float_of_int n
   | Number n -> n
   | Bool true -> 1.0
   | Bool false -> 0.0
@@ -79,6 +87,7 @@ let as_bool = function
 
 let rec to_string = function
   | String s -> s
+  | Integer n -> string_of_int n
   | Number n -> Sx_types.format_number n
   | Bool true -> "true"
   | Bool false -> "false"
@@ -93,49 +102,81 @@ let rec to_string = function
 let () =
   (* === Arithmetic === *)
   register "+" (fun args ->
-    Number (List.fold_left (fun acc a -> acc +. as_number a) 0.0 args));
+    if all_ints args then
+      Integer (List.fold_left (fun acc a -> match a with Integer n -> acc + n | _ -> acc) 0 args)
+    else
+      Number (List.fold_left (fun acc a -> acc +. as_number a) 0.0 args));
   register "-" (fun args ->
     match args with
-    | [] -> Number 0.0
+    | [] -> Integer 0
+    | [Integer n] -> Integer (-n)
     | [a] -> Number (-. (as_number a))
-    | a :: rest -> Number (List.fold_left (fun acc x -> acc -. as_number x) (as_number a) rest));
+    | _ when all_ints args ->
+      (match args with
+       | Integer h :: tl ->
+         Integer (List.fold_left (fun acc a -> match a with Integer n -> acc - n | _ -> acc) h tl)
+       | _ -> Number 0.0)
+    | a :: rest ->
+      Number (List.fold_left (fun acc x -> acc -. as_number x) (as_number a) rest));
   register "*" (fun args ->
-    Number (List.fold_left (fun acc a -> acc *. as_number a) 1.0 args));
+    if all_ints args then
+      Integer (List.fold_left (fun acc a -> match a with Integer n -> acc * n | _ -> acc) 1 args)
+    else
+      Number (List.fold_left (fun acc a -> acc *. as_number a) 1.0 args));
   register "/" (fun args ->
     match args with
     | [a; b] -> Number (as_number a /. as_number b)
     | _ -> raise (Eval_error "/: expected 2 args"));
   register "mod" (fun args ->
     match args with
+    | [Integer a; Integer b] -> Integer (a mod b)
     | [a; b] -> Number (Float.rem (as_number a) (as_number b))
     | _ -> raise (Eval_error "mod: expected 2 args"));
   register "inc" (fun args ->
-    match args with [a] -> Number (as_number a +. 1.0) | _ -> raise (Eval_error "inc: 1 arg"));
+    match args with
+    | [Integer n] -> Integer (n + 1)
+    | [a] -> Number (as_number a +. 1.0)
+    | _ -> raise (Eval_error "inc: 1 arg"));
   register "dec" (fun args ->
-    match args with [a] -> Number (as_number a -. 1.0) | _ -> raise (Eval_error "dec: 1 arg"));
+    match args with
+    | [Integer n] -> Integer (n - 1)
+    | [a] -> Number (as_number a -. 1.0)
+    | _ -> raise (Eval_error "dec: 1 arg"));
   register "abs" (fun args ->
-    match args with [a] -> Number (Float.abs (as_number a)) | _ -> raise (Eval_error "abs: 1 arg"));
+    match args with
+    | [Integer n] -> Integer (abs n)
+    | [a] -> Number (Float.abs (as_number a))
+    | _ -> raise (Eval_error "abs: 1 arg"));
   register "floor" (fun args ->
-    match args with [a] -> Number (floor (as_number a))
+    match args with
+    | [Integer n] -> Integer n
+    | [a] -> Integer (int_of_float (floor (as_number a)))
     | _ -> raise (Eval_error "floor: 1 arg"));
   register "ceil" (fun args ->
-    match args with [a] -> Number (ceil (as_number a))
+    match args with
+    | [Integer n] -> Integer n
+    | [a] -> Integer (int_of_float (ceil (as_number a)))
     | _ -> raise (Eval_error "ceil: 1 arg"));
   register "round" (fun args ->
     match args with
-    | [a] -> Number (Float.round (as_number a))
+    | [Integer n] -> Integer n
+    | [a] -> Integer (int_of_float (Float.round (as_number a)))
     | [a; b] ->
-      let n = as_number a and places = int_of_float (as_number b) in
+      let n = as_number a and places = as_int b in
       let factor = 10.0 ** float_of_int places in
       Number (Float.round (n *. factor) /. factor)
     | _ -> raise (Eval_error "round: 1-2 args"));
   register "min" (fun args ->
     match args with
     | [] -> raise (Eval_error "min: at least 1 arg")
+    | _ when all_ints args ->
+      Integer (List.fold_left (fun acc a -> match a with Integer n -> min acc n | _ -> acc) max_int args)
     | _ -> Number (List.fold_left (fun acc a -> Float.min acc (as_number a)) Float.infinity args));
   register "max" (fun args ->
     match args with
     | [] -> raise (Eval_error "max: at least 1 arg")
+    | _ when all_ints args ->
+      Integer (List.fold_left (fun acc a -> match a with Integer n -> max acc n | _ -> acc) min_int args)
     | _ -> Number (List.fold_left (fun acc a -> Float.max acc (as_number a)) Float.neg_infinity args));
   register "sqrt" (fun args ->
     match args with [a] -> Number (Float.sqrt (as_number a)) | _ -> raise (Eval_error "sqrt: 1 arg"));
@@ -189,6 +230,7 @@ let () =
     Number (Float.sqrt sum));
   register "sign" (fun args ->
     match args with
+    | [Integer n] -> Integer (if n > 0 then 1 else if n < 0 then -1 else 0)
     | [a] ->
       let n = as_number a in
       Number (if Float.is_nan n then Float.nan
@@ -234,32 +276,47 @@ let () =
     | _ -> raise (Eval_error "clamp: 3 args"));
   register "truncate" (fun args ->
     match args with
-    | [a] -> let n = as_number a in Number (if n >= 0.0 then floor n else ceil n)
+    | [Integer n] -> Integer n
+    | [a] -> let n = as_number a in Integer (int_of_float (if n >= 0.0 then floor n else ceil n))
     | _ -> raise (Eval_error "truncate: 1 arg"));
   register "remainder" (fun args ->
     match args with
+    | [Integer a; Integer b] -> Integer (a mod b)
     | [a; b] -> Number (Float.rem (as_number a) (as_number b))
     | _ -> raise (Eval_error "remainder: 2 args"));
   register "modulo" (fun args ->
     match args with
+    | [Integer a; Integer b] ->
+      let r = a mod b in
+      Integer (if r = 0 || (r > 0) = (b > 0) then r else r + b)
     | [a; b] ->
       let a = as_number a and b = as_number b in
       let r = Float.rem a b in
       Number (if r = 0.0 || (r > 0.0) = (b > 0.0) then r else r +. b)
     | _ -> raise (Eval_error "modulo: 2 args"));
   register "exact?" (fun args ->
-    match args with [Number f] -> Bool (Float.is_integer f) | [_] -> Bool false
+    match args with
+    | [Integer _] -> Bool true
+    | [Number _] -> Bool false
+    | [_] -> Bool false
     | _ -> raise (Eval_error "exact?: 1 arg"));
   register "inexact?" (fun args ->
-    match args with [Number f] -> Bool (not (Float.is_integer f)) | [_] -> Bool false
+    match args with
+    | [Number _] -> Bool true
+    | [Integer _] -> Bool false
+    | [_] -> Bool false
     | _ -> raise (Eval_error "inexact?: 1 arg"));
   register "exact->inexact" (fun args ->
-    match args with [Number n] -> Number n | [a] -> Number (as_number a)
+    match args with
+    | [Integer n] -> Number (float_of_int n)
+    | [Number n] -> Number n
+    | [a] -> Number (as_number a)
     | _ -> raise (Eval_error "exact->inexact: 1 arg"));
   register "inexact->exact" (fun args ->
     match args with
-    | [Number n] -> if Float.is_integer n then Number n else Number (Float.round n)
+    | [Integer n] -> Integer n
-    | [a] -> Number (Float.round (as_number a))
+    | [Number n] -> Integer (int_of_float (Float.round n))
+    | [a] -> Integer (int_of_float (Float.round (as_number a)))
     | _ -> raise (Eval_error "inexact->exact: 1 arg"));
   register "parse-int" (fun args ->
     let parse_leading_int s =
@@ -276,10 +333,11 @@ let () =
       else None
     in
     match args with
-    | [String s] -> (match parse_leading_int s with Some n -> Number (float_of_int n) | None -> Nil)
+    | [String s] -> (match parse_leading_int s with Some n -> Integer n | None -> Nil)
     | [String s; default_val] ->
-      (match parse_leading_int s with Some n -> Number (float_of_int n) | None -> default_val)
+      (match parse_leading_int s with Some n -> Integer n | None -> default_val)
-    | [Number n] | [Number n; _] -> Number (float_of_int (int_of_float n))
+    | [Integer n] | [Integer n; _] -> Integer n
+    | [Number n] | [Number n; _] -> Integer (int_of_float n)
     | [_; default_val] -> default_val
     | _ -> Nil);
   register "parse-float" (fun args ->
@@ -296,7 +354,10 @@ let () =
   let rec safe_eq a b =
     if a == b then true  (* physical equality fast path *)
     else match a, b with
+    | Integer x, Integer y -> x = y
     | Number x, Number y -> x = y
+    | Integer x, Number y -> float_of_int x = y
+    | Number x, Integer y -> x = float_of_int y
     | String x, String y -> x = y
     | Bool x, Bool y -> x = y
     | Nil, Nil -> true
@@ -368,9 +429,21 @@ let () =
   register "nil?" (fun args ->
     match args with [a] -> Bool (is_nil a) | _ -> raise (Eval_error "nil?: 1 arg"));
   register "number?" (fun args ->
-    match args with [Number _] -> Bool true | [_] -> Bool false | _ -> raise (Eval_error "number?: 1 arg"));
+    match args with
+    | [Integer _] | [Number _] -> Bool true
+    | [_] -> Bool false
+    | _ -> raise (Eval_error "number?: 1 arg"));
   register "integer?" (fun args ->
-    match args with [Number f] -> Bool (Float.is_integer f) | [_] -> Bool false | _ -> raise (Eval_error "integer?: 1 arg"));
+    match args with
+    | [Integer _] -> Bool true
+    | [Number f] -> Bool (Float.is_integer f)
+    | [_] -> Bool false
+    | _ -> raise (Eval_error "integer?: 1 arg"));
+  register "float?" (fun args ->
+    match args with
+    | [Number _] -> Bool true
+    | [_] -> Bool false
+    | _ -> raise (Eval_error "float?: 1 arg"));
   register "string?" (fun args ->
     match args with [String _] -> Bool true | [_] -> Bool false | _ -> raise (Eval_error "string?: 1 arg"));
   register "boolean?" (fun args ->
@@ -412,7 +485,7 @@ let () =
   register "trim" (fun args ->
     match args with [a] -> String (String.trim (as_string a)) | _ -> raise (Eval_error "trim: 1 arg"));
   register "string-length" (fun args ->
-    match args with [a] -> Number (float_of_int (String.length (as_string a)))
+    match args with [a] -> Integer (String.length (as_string a))
     | _ -> raise (Eval_error "string-length: 1 arg"));
   register "string-contains?" (fun args ->
     match args with
@@ -446,7 +519,11 @@ let () =
       in find 0
     | [List items; target] | [ListRef { contents = items }; target] ->
       let eq a b = match a, b with
-        | String x, String y -> x = y | Number x, Number y -> x = y
+        | Integer x, Integer y -> x = y
+        | Number x, Number y -> x = y
+        | Integer x, Number y -> float_of_int x = y
+        | Number x, Integer y -> x = float_of_int y
+        | String x, String y -> x = y
         | Symbol x, Symbol y -> x = y | Keyword x, Keyword y -> x = y
         | Bool x, Bool y -> x = y | Nil, Nil -> true | _ -> a == b in
       let rec find i = function
@@ -457,22 +534,22 @@ let () =
     | _ -> raise (Eval_error "index-of: 2 string args or list+target"));
   register "substring" (fun args ->
     match args with
-    | [String s; Number start; Number end_] ->
+    | [String s; start_v; end_v] ->
-      let i = int_of_float start and j = int_of_float end_ in
+      let i = as_int start_v and j = as_int end_v in
       let len = String.length s in
       let i = max 0 (min i len) and j = max 0 (min j len) in
       String (String.sub s i (max 0 (j - i)))
     | _ -> raise (Eval_error "substring: 3 args"));
   register "substr" (fun args ->
     match args with
-    | [String s; Number start; Number len] ->
+    | [String s; start_v; len_v] ->
-      let i = int_of_float start and n = int_of_float len in
+      let i = as_int start_v and n = as_int len_v in
       let sl = String.length s in
       let i = max 0 (min i sl) in
       let n = max 0 (min n (sl - i)) in
       String (String.sub s i n)
-    | [String s; Number start] ->
+    | [String s; start_v] ->
-      let i = int_of_float start in
+      let i = as_int start_v in
       let sl = String.length s in
       let i = max 0 (min i sl) in
       String (String.sub s i (sl - i))
@@ -497,6 +574,7 @@ let () =
       | String s -> s | SxExpr s -> s | RawHTML s -> s
       | Keyword k -> k | Symbol s -> s
       | Nil -> "" | Bool true -> "true" | Bool false -> "false"
+      | Integer n -> string_of_int n
       | Number n -> if Float.is_integer n then string_of_int (int_of_float n) else Printf.sprintf "%g" n
       | Thunk _ as t -> (match !_sx_trampoline_fn t with String s -> s | v -> to_string v)
       | v -> to_string v
@@ -523,28 +601,35 @@ let () =
     | _ -> raise (Eval_error "replace: 3 string args"));
   register "char-from-code" (fun args ->
     match args with
-    | [Number n] ->
+    | [a] ->
+      let n = as_int a in
       let buf = Buffer.create 4 in
-      Buffer.add_utf_8_uchar buf (Uchar.of_int (int_of_float n));
+      Buffer.add_utf_8_uchar buf (Uchar.of_int n);
       String (Buffer.contents buf)
     | _ -> raise (Eval_error "char-from-code: 1 arg"));
   register "char-at" (fun args ->
     match args with
-    | [String s; Number n] ->
+    | [String s; n] ->
-      let i = int_of_float n in
+      let i = as_int n in
       if i >= 0 && i < String.length s then
         String (String.make 1 s.[i])
       else Nil
     | _ -> raise (Eval_error "char-at: string and index"));
   register "char-code" (fun args ->
     match args with
-    | [String s] when String.length s > 0 -> Number (float_of_int (Char.code s.[0]))
+    | [String s] when String.length s > 0 -> Integer (Char.code s.[0])
     | _ -> raise (Eval_error "char-code: 1 non-empty string arg"));
   register "parse-number" (fun args ->
     match args with
     | [String s] ->
-      (try Number (float_of_string s)
+      let has_dec = String.contains s '.' in
-       with Failure _ -> Nil)
+      let has_exp = String.contains s 'e' || String.contains s 'E' in
+      if has_dec || has_exp then
+        (try Number (float_of_string s) with Failure _ -> Nil)
+      else
+        (match int_of_string_opt s with
+         | Some n -> Integer n
+         | None -> (try Number (float_of_string s) with Failure _ -> Nil))
     | _ -> raise (Eval_error "parse-number: 1 string arg"));
 
   (* === Regex (PCRE-compatible — same syntax as JS RegExp) === *)
@@ -621,17 +706,17 @@ let () =
   register "list" (fun args -> ListRef (ref args));
   register "len" (fun args ->
     match args with
-    | [List l] | [ListRef { contents = l }] -> Number (float_of_int (List.length l))
+    | [List l] | [ListRef { contents = l }] -> Integer (List.length l)
-    | [String s] -> Number (float_of_int (String.length s))
+    | [String s] -> Integer (String.length s)
-    | [Dict d] -> Number (float_of_int (Hashtbl.length d))
+    | [Dict d] -> Integer (Hashtbl.length d)
-    | [Nil] | [Bool false] -> Number 0.0
+    | [Nil] | [Bool false] -> Integer 0
-    | [Bool true] -> Number 1.0
+    | [Bool true] -> Integer 1
-    | [Number _] -> Number 1.0
+    | [Number _] | [Integer _] -> Integer 1
-    | [RawHTML s] -> Number (float_of_int (String.length s))
+    | [RawHTML s] -> Integer (String.length s)
-    | [SxExpr s] -> Number (float_of_int (String.length s))
+    | [SxExpr s] -> Integer (String.length s)
-    | [Spread pairs] -> Number (float_of_int (List.length pairs))
+    | [Spread pairs] -> Integer (List.length pairs)
     | [Component _] | [Island _] | [Lambda _] | [NativeFn _]
-    | [Macro _] | [Thunk _] | [Keyword _] | [Symbol _] -> Number 0.0
+    | [Macro _] | [Thunk _] | [Keyword _] | [Symbol _] -> Integer 0
     | _ -> raise (Eval_error (Printf.sprintf "len: %d args"
         (List.length args))));
   register "length" (Hashtbl.find primitives "len");
@@ -658,10 +743,10 @@ let () =
     | _ -> raise (Eval_error "init: 1 list arg"));
   register "nth" (fun args ->
     match args with
-    | [List l; Number n] | [ListRef { contents = l }; Number n] ->
+    | [List l; n] | [ListRef { contents = l }; n] ->
-      (try List.nth l (int_of_float n) with _ -> Nil)
+      (try List.nth l (as_int n) with _ -> Nil)
-    | [String s; Number n] ->
+    | [String s; n] ->
-      let i = int_of_float n in
+      let i = as_int n in
       if i >= 0 && i < String.length s then String (String.make 1 s.[i])
       else Nil
     | _ -> raise (Eval_error "nth: list/string and number"));
@@ -707,7 +792,10 @@ let () =
       let safe_eq a b =
         a == b ||
         (match a, b with
+         | Integer x, Integer y -> x = y
          | Number x, Number y -> x = y
+         | Integer x, Number y -> float_of_int x = y
+         | Number x, Integer y -> x = float_of_int y
          | String x, String y -> x = y
          | Bool x, Bool y -> x = y
          | Nil, Nil -> true
@@ -729,33 +817,45 @@ let () =
     | _ -> raise (Eval_error "contains?: 2 args"));
   register "range" (fun args ->
     match args with
-    | [Number stop] ->
+    | [stop_v] ->
-      let n = int_of_float stop in
+      let n = as_int stop_v in
-      List (List.init (max 0 n) (fun i -> Number (float_of_int i)))
+      List (List.init (max 0 n) (fun i -> Integer i))
-    | [Number start; Number stop] ->
+    | [start_v; stop_v] ->
-      let s = int_of_float start and e = int_of_float stop in
+      let s = as_int start_v and e = as_int stop_v in
       let len = max 0 (e - s) in
-      List (List.init len (fun i -> Number (float_of_int (s + i))))
+      List (List.init len (fun i -> Integer (s + i)))
-    | [Number start; Number stop; Number step] ->
+    | [start_v; stop_v; step_v] ->
-      let s = start and e = stop and st = step in
+      (match start_v, stop_v, step_v with
-      if st = 0.0 then List []
+       | Integer s, Integer e, Integer st ->
-      else
+         if st = 0 then List []
-        let items = ref [] in
+         else
-        let i = ref s in
+           let items = ref [] in
-        if st > 0.0 then
+           let i = ref s in
-          (while !i < e do items := Number !i :: !items; i := !i +. st done)
+           if st > 0 then
-        else
+             (while !i < e do items := Integer !i :: !items; i := !i + st done)
-          (while !i > e do items := Number !i :: !items; i := !i +. st done);
+           else
-        List (List.rev !items)
+             (while !i > e do items := Integer !i :: !items; i := !i + st done);
+           List (List.rev !items)
+       | _ ->
+         let s = as_number start_v and e = as_number stop_v and st = as_number step_v in
+         if st = 0.0 then List []
+         else
+           let items = ref [] in
+           let i = ref s in
+           if st > 0.0 then
+             (while !i < e do items := Number !i :: !items; i := !i +. st done)
+           else
+             (while !i > e do items := Number !i :: !items; i := !i +. st done);
+           List (List.rev !items))
     | _ -> raise (Eval_error "range: 1-3 args"));
   register "slice" (fun args ->
     match args with
-    | [(List l | ListRef { contents = l }); Number start] ->
+    | [(List l | ListRef { contents = l }); start_v] ->
-      let i = max 0 (int_of_float start) in
+      let i = max 0 (as_int start_v) in
       let rec drop n = function _ :: xs when n > 0 -> drop (n-1) xs | l -> l in
       List (drop i l)
-    | [(List l | ListRef { contents = l }); Number start; Number end_] ->
+    | [(List l | ListRef { contents = l }); start_v; end_v] ->
-      let i = max 0 (int_of_float start) and j = int_of_float end_ in
+      let i = max 0 (as_int start_v) and j = as_int end_v in
       let len = List.length l in
       let j = min j len in
       let rec take_range idx = function
@@ -765,11 +865,11 @@ let () =
           else if idx >= i then x :: take_range (idx+1) xs
           else take_range (idx+1) xs
       in List (take_range 0 l)
-    | [String s; Number start] ->
+    | [String s; start_v] ->
-      let i = max 0 (int_of_float start) in
+      let i = max 0 (as_int start_v) in
       String (String.sub s i (max 0 (String.length s - i)))
-    | [String s; Number start; Number end_] ->
+    | [String s; start_v; end_v] ->
-      let i = max 0 (int_of_float start) and j = int_of_float end_ in
+      let i = max 0 (as_int start_v) and j = as_int end_v in
       let sl = String.length s in
       let j = min j sl in
       String (String.sub s i (max 0 (j - i)))
@@ -798,24 +898,24 @@ let () =
     | _ -> raise (Eval_error "zip-pairs: 1 list"));
   register "take" (fun args ->
     match args with
-    | [(List l | ListRef { contents = l }); Number n] ->
+    | [(List l | ListRef { contents = l }); n] ->
       let rec take_n i = function
         | x :: xs when i > 0 -> x :: take_n (i-1) xs
         | _ -> []
-      in List (take_n (int_of_float n) l)
+      in List (take_n (as_int n) l)
     | _ -> raise (Eval_error "take: list and number"));
   register "drop" (fun args ->
     match args with
-    | [(List l | ListRef { contents = l }); Number n] ->
+    | [(List l | ListRef { contents = l }); n] ->
       let rec drop_n i = function
         | _ :: xs when i > 0 -> drop_n (i-1) xs
         | l -> l
-      in List (drop_n (int_of_float n) l)
+      in List (drop_n (as_int n) l)
     | _ -> raise (Eval_error "drop: list and number"));
   register "chunk-every" (fun args ->
     match args with
-    | [(List l | ListRef { contents = l }); Number n] ->
+    | [(List l | ListRef { contents = l }); n] ->
-      let size = int_of_float n in
+      let size = as_int n in
       let rec go = function
         | [] -> []
         | l ->
@@ -855,8 +955,9 @@ let () =
     match args with
     | [Dict d; String k] -> dict_get d k
     | [Dict d; Keyword k] -> dict_get d k
-    | [List l; Number n] | [ListRef { contents = l }; Number n] ->
+    | [List l; n] | [ListRef { contents = l }; n]
-      (try List.nth l (int_of_float n) with _ -> Nil)
+        when (match n with Number _ | Integer _ -> true | _ -> false) ->
+      (try List.nth l (as_int n) with _ -> Nil)
     | [Nil; _] -> Nil  (* nil.anything → nil *)
     | [_; _] -> Nil    (* type mismatch → nil (matches JS/Python behavior) *)
     | _ -> Nil);
@@ -897,8 +998,8 @@ let () =
   register "mutable-list" (fun _args -> ListRef (ref []));
   register "set-nth!" (fun args ->
     match args with
-    | [ListRef r; Number n; v] ->
+    | [ListRef r; idx; v] ->
-      let i = int_of_float n in
+      let i = as_int idx in
       let l = !r in
       r := List.mapi (fun j x -> if j = i then v else x) l;
       Nil
@@ -1025,15 +1126,15 @@ let () =
   register "identical?" (fun args ->
     match args with
     | [a; b] ->
-      (* Physical identity for reference types, structural for values.
-         Numbers/strings/booleans from different constant pools must
-         compare equal when their values match. *)
       let identical = match a, b with
+        | Integer x, Integer y -> x = y
         | Number x, Number y -> x = y
-        | String x, String y -> x = y  (* String.equal *)
+        | Integer x, Number y -> float_of_int x = y
+        | Number x, Integer y -> x = float_of_int y
+        | String x, String y -> x = y
         | Bool x, Bool y -> x = y
         | Nil, Nil -> true
-        | _ -> a == b  (* reference identity for dicts, lists, etc. *)
+        | _ -> a == b
       in Bool identical
     | _ -> raise (Eval_error "identical?: 2 args"));
   register "make-spread" (fun args ->
@@ -1071,7 +1172,7 @@ let () =
   register "map-indexed" (fun args ->
     match args with
     | [f; (List items | ListRef { contents = items })] ->
-      List (List.mapi (fun i x -> call_any f [Number (float_of_int i); x]) items)
+      List (List.mapi (fun i x -> call_any f [Integer i; x]) items)
     | [_; Nil] -> List []
     | _ -> raise (Eval_error "map-indexed: expected (fn list)"));
   register "filter" (fun args ->
@@ -1114,26 +1215,26 @@ let () =
   (* ---- VM stack primitives (vm.sx platform interface) ---- *)
   register "make-vm-stack" (fun args ->
     match args with
-    | [Number n] -> ListRef (ref (List.init (int_of_float n) (fun _ -> Nil)))
+    | [n] -> ListRef (ref (List.init (as_int n) (fun _ -> Nil)))
     | _ -> raise (Eval_error "make-vm-stack: expected (size)"));
   register "vm-stack-get" (fun args ->
     match args with
-    | [ListRef r; Number n] -> List.nth !r (int_of_float n)
+    | [ListRef r; n] -> List.nth !r (as_int n)
     | _ -> raise (Eval_error "vm-stack-get: expected (stack idx)"));
   register "vm-stack-set!" (fun args ->
     match args with
-    | [ListRef r; Number n; v] ->
+    | [ListRef r; n; v] ->
-      let i = int_of_float n in
+      let i = as_int n in
       r := List.mapi (fun j x -> if j = i then v else x) !r; Nil
     | _ -> raise (Eval_error "vm-stack-set!: expected (stack idx val)"));
   register "vm-stack-length" (fun args ->
     match args with
-    | [ListRef r] -> Number (float_of_int (List.length !r))
+    | [ListRef r] -> Integer (List.length !r)
     | _ -> raise (Eval_error "vm-stack-length: expected (stack)"));
   register "vm-stack-copy!" (fun args ->
     match args with
-    | [ListRef src; ListRef dst; Number n] ->
+    | [ListRef src; ListRef dst; n] ->
-      let count = int_of_float n in
+      let count = as_int n in
       let src_items = !src in
       dst := List.mapi (fun i x -> if i < count then List.nth src_items i else x) !dst; Nil
     | _ -> raise (Eval_error "vm-stack-copy!: expected (src dst count)"));
@@ -1215,28 +1316,28 @@ let () =
   (* R7RS vectors — mutable fixed-size arrays *)
   register "make-vector" (fun args ->
     match args with
-    | [Number n] -> Vector (Array.make (int_of_float n) Nil)
+    | [n] -> Vector (Array.make (as_int n) Nil)
-    | [Number n; fill] -> Vector (Array.make (int_of_float n) fill)
+    | [n; fill] -> Vector (Array.make (as_int n) fill)
     | _ -> raise (Eval_error "make-vector: expected (length) or (length fill)"));
   register "vector" (fun args -> Vector (Array.of_list args));
   register "vector?" (fun args ->
     match args with [Vector _] -> Bool true | [_] -> Bool false
     | _ -> raise (Eval_error "vector?: 1 arg"));
   register "vector-length" (fun args ->
-    match args with [Vector arr] -> Number (float_of_int (Array.length arr))
+    match args with [Vector arr] -> Integer (Array.length arr)
     | _ -> raise (Eval_error "vector-length: expected vector"));
   register "vector-ref" (fun args ->
     match args with
-    | [Vector arr; Number n] ->
+    | [Vector arr; n] ->
-      let i = int_of_float n in
+      let i = as_int n in
       if i < 0 || i >= Array.length arr then
         raise (Eval_error (Printf.sprintf "vector-ref: index %d out of bounds (length %d)" i (Array.length arr)));
       arr.(i)
     | _ -> raise (Eval_error "vector-ref: expected (vector index)"));
   register "vector-set!" (fun args ->
     match args with
-    | [Vector arr; Number n; v] ->
+    | [Vector arr; n; v] ->
-      let i = int_of_float n in
+      let i = as_int n in
       if i < 0 || i >= Array.length arr then
         raise (Eval_error (Printf.sprintf "vector-set!: index %d out of bounds (length %d)" i (Array.length arr)));
       arr.(i) <- v; Nil
@@ -1256,13 +1357,13 @@ let () =
   register "vector-copy" (fun args ->
     match args with
     | [Vector arr] -> Vector (Array.copy arr)
-    | [Vector arr; Number s] ->
+    | [Vector arr; s] ->
-      let start = int_of_float s in
+      let start = as_int s in
       let len = Array.length arr - start in
       if len <= 0 then Vector [||] else Vector (Array.sub arr start len)
-    | [Vector arr; Number s; Number e] ->
+    | [Vector arr; s; e] ->
-      let start = int_of_float s in
+      let start = as_int s in
-      let stop = min (int_of_float e) (Array.length arr) in
+      let stop = min (as_int e) (Array.length arr) in
       let len = stop - start in
       if len <= 0 then Vector [||] else Vector (Array.sub arr start len)
     | _ -> raise (Eval_error "vector-copy: expected (vector) or (vector start) or (vector start end)"));

hosts/ocaml/lib/sx_types.ml

@@ -43,9 +43,10 @@ type env = {
 
 and value =
   | Nil
-  | Bool   of bool
+  | Bool    of bool
-  | Number of float
+  | Integer of int    (** Exact integer — distinct from inexact float. *)
-  | String of string
+  | Number  of float  (** Inexact float. *)
+  | String  of string
   | Symbol of string
   | Keyword of string
   | List   of value list
@@ -392,6 +393,7 @@ let format_number n =
 
 let value_to_string = function
   | String s -> s | Symbol s -> s | Keyword k -> k
+  | Integer n -> string_of_int n
   | Number n -> format_number n
   | Bool true -> "true" | Bool false -> "false"
   | Nil -> "" | _ -> "<value>"
@@ -461,6 +463,7 @@ let make_keyword name = Keyword (value_to_string name)
 let type_of = function
   | Nil            -> "nil"
   | Bool _         -> "boolean"
+  | Integer _      -> "number"
   | Number _       -> "number"
   | String _       -> "string"
   | Symbol _       -> "symbol"
@@ -616,6 +619,7 @@ let thunk_env = function
 (** {1 Record operations} *)
 
 let val_to_int = function
+  | Integer n -> n
   | Number n -> int_of_float n
   | v -> raise (Eval_error ("Expected number, got " ^ type_of v))
 
@@ -777,6 +781,7 @@ let rec inspect = function
   | Nil -> "nil"
   | Bool true -> "true"
   | Bool false -> "false"
+  | Integer n -> string_of_int n
   | Number n -> format_number n
   | String s ->
     let buf = Buffer.create (String.length s + 2) in

hosts/ocaml/lib/sx_vm.ml

@@ -185,7 +185,8 @@ let code_from_value v =
       | Some _ as r -> r | None -> Hashtbl.find_opt d k2 in
     let bc_list = match find2 "bytecode" "vc-bytecode" with
       | Some (List l | ListRef { contents = l }) ->
-        Array.of_list (List.map (fun x -> match x with Number n -> int_of_float n | _ -> 0) l)
+        Array.of_list (List.map (fun x -> match x with
+          | Integer n -> n | Number n -> int_of_float n | _ -> 0) l)
       | _ -> [||]
     in
     let entries = match find2 "constants" "vc-constants" with
@@ -198,10 +199,10 @@ let code_from_value v =
       | _ -> entry
     ) entries in
     let arity = match find2 "arity" "vc-arity" with
-      | Some (Number n) -> int_of_float n | _ -> 0
+      | Some (Integer n) -> n | Some (Number n) -> int_of_float n | _ -> 0
     in
     let rest_arity = match find2 "rest-arity" "vc-rest-arity" with
-      | Some (Number n) -> int_of_float n | _ -> -1
+      | Some (Integer n) -> n | Some (Number n) -> int_of_float n | _ -> -1
     in
     (* Compute locals from bytecode: scan for highest LOCAL_GET/LOCAL_SET slot.
        The compiler's arity may undercount when nested lets add many locals. *)
@@ -749,10 +750,7 @@ and run vm =
             | _ -> (Hashtbl.find Sx_primitives.primitives "/") [a; b])
         | 164 (* OP_EQ *) ->
           let b = pop vm and a = pop vm in
-          let rec norm = function
+          push vm ((Hashtbl.find Sx_primitives.primitives "=") [a; b])
-            | ListRef { contents = l } -> List (List.map norm l)
-            | List l -> List (List.map norm l) | v -> v in
-          push vm (Bool (norm a = norm b))
         | 165 (* OP_LT *) ->
           let b = pop vm and a = pop vm in
           push vm (match a, b with
@@ -771,10 +769,10 @@ and run vm =
         | 168 (* OP_LEN *) ->
           let v = pop vm in
           push vm (match v with
-            | List l | ListRef { contents = l } -> Number (float_of_int (List.length l))
+            | List l | ListRef { contents = l } -> Integer (List.length l)
-            | String s -> Number (float_of_int (String.length s))
+            | String s -> Integer (String.length s)
-            | Dict d -> Number (float_of_int (Hashtbl.length d))
+            | Dict d -> Integer (Hashtbl.length d)
-            | Nil -> Number 0.0
+            | Nil -> Integer 0
             | _ -> (Hashtbl.find Sx_primitives.primitives "len") [v])
         | 169 (* OP_FIRST *) ->
           let v = pop vm in

spec/tests/test-numeric-tower.sx

@@ -0,0 +1,221 @@
+
+;; ==========================================================================
+;; test-numeric-tower.sx — Numeric tower: Integer vs Float distinction
+;;
+;; Tests for float contagion, integer arithmetic, predicates,
+;; coercions, parsing, and rendering.
+;;
+;; Note: Use fractional floats (1.5, 3.14) or exact->inexact for round floats,
+;; since the SX serializer renders Number 1.0 as "1" (int form).
+;; ==========================================================================
+
+;; --------------------------------------------------------------------------
+;; Integer arithmetic — result stays Integer when all args are Integer
+;; --------------------------------------------------------------------------
+
+(defsuite
+  "numeric-tower:int-arithmetic"
+  (deftest "int + int = int" (assert (integer? (+ 1 2))))
+  (deftest "int + int value" (assert= (+ 1 2) 3))
+  (deftest "int - int = int" (assert (integer? (- 10 3))))
+  (deftest "int - int value" (assert= (- 10 3) 7))
+  (deftest "int * int = int" (assert (integer? (* 4 5))))
+  (deftest "int * int value" (assert= (* 4 5) 20))
+  (deftest "zero identity" (assert= (+ 0 0) 0))
+  (deftest "negative int" (assert= (- 0 5) -5))
+  (deftest
+    "int negation is int"
+    (assert (integer? (- 0 7))))
+  (deftest
+    "large int product"
+    (assert= (* 100 100) 10000)))
+
+;; --------------------------------------------------------------------------
+;; Float contagion — any float arg promotes result to float
+;; --------------------------------------------------------------------------
+
+(defsuite
+  "numeric-tower:float-contagion"
+  (deftest "int + float = float" (assert (float? (+ 1 1.5))))
+  (deftest "int + float value" (assert= (+ 1 1.5) 2.5))
+  (deftest "float + int = float" (assert (float? (+ 1.5 2))))
+  (deftest "float + float = float" (assert (float? (+ 1.5 2.5))))
+  (deftest "int * float = float" (assert (float? (* 2 1.5))))
+  (deftest "int * float value" (assert= (* 2 1.5) 3))
+  (deftest "int - float = float" (assert (float? (- 5 2.5))))
+  (deftest "float - int = float" (assert (float? (- 5.5 2))))
+  (deftest
+    "three args with float"
+    (assert (float? (+ 1 2 3.5))))
+  (deftest
+    "exact->inexact promotes to float"
+    (assert (float? (exact->inexact 5)))))
+
+;; --------------------------------------------------------------------------
+;; Division always returns float
+;; --------------------------------------------------------------------------
+
+(defsuite
+  "numeric-tower:division"
+  (deftest "int / int = float" (assert (float? (/ 6 2))))
+  (deftest "exact division value" (assert= (/ 6 2) 3))
+  (deftest "inexact division" (assert= (/ 1 4) 0.25))
+  (deftest "float / float = float" (assert (float? (/ 3.5 2.5)))))
+
+;; --------------------------------------------------------------------------
+;; Type predicates
+;; --------------------------------------------------------------------------
+
+(defsuite
+  "numeric-tower:predicates"
+  (deftest "integer? on int" (assert (integer? 42)))
+  (deftest "integer? on negative" (assert (integer? -7)))
+  (deftest "integer? on zero" (assert (integer? 0)))
+  (deftest
+    "integer? on float-int"
+    (assert (integer? (exact->inexact 2))))
+  (deftest "integer? on fractional float" (assert (not (integer? 1.5))))
+  (deftest "float? on 1.5" (assert (float? 1.5)))
+  (deftest
+    "float? on exact->inexact"
+    (assert (float? (exact->inexact 2))))
+  (deftest "float? on int" (assert (not (float? 42))))
+  (deftest "number? on int" (assert (number? 42)))
+  (deftest "number? on float" (assert (number? 3.14)))
+  (deftest "number? on string" (assert (not (number? "42"))))
+  (deftest "exact? on int" (assert (exact? 1)))
+  (deftest
+    "exact? on exact->inexact"
+    (assert (not (exact? (exact->inexact 1)))))
+  (deftest "inexact? on 1.5" (assert (inexact? 1.5)))
+  (deftest "inexact? on int" (assert (not (inexact? 3)))))
+
+;; --------------------------------------------------------------------------
+;; Coercions
+;; --------------------------------------------------------------------------
+
+(defsuite
+  "numeric-tower:coercions"
+  (deftest "exact->inexact int" (assert= (exact->inexact 3) 3))
+  (deftest
+    "exact->inexact produces float"
+    (assert (float? (exact->inexact 5))))
+  (deftest
+    "exact->inexact float passthrough"
+    (assert= (exact->inexact 1.5) 1.5))
+  (deftest "inexact->exact 1.5" (assert= (inexact->exact 1.5) 2))
+  (deftest
+    "inexact->exact produces int"
+    (assert (integer? (inexact->exact (exact->inexact 4)))))
+  (deftest "inexact->exact 2.7" (assert= (inexact->exact 2.7) 3))
+  (deftest
+    "inexact->exact int passthrough"
+    (assert= (inexact->exact 5) 5)))
+
+;; --------------------------------------------------------------------------
+;; floor / ceiling / truncate / round — return Integer for floats
+;; --------------------------------------------------------------------------
+
+(defsuite
+  "numeric-tower:rounding"
+  (deftest "floor 3.7" (assert= (floor 3.7) 3))
+  (deftest "floor produces int" (assert (integer? (floor 3.7))))
+  (deftest "floor negative" (assert= (floor -2.3) -3))
+  (deftest "truncate 3.9" (assert= (truncate 3.9) 3))
+  (deftest "truncate negative" (assert= (truncate -3.9) -3))
+  (deftest "truncate produces int" (assert (integer? (truncate 3.9))))
+  (deftest "round 2.3 down" (assert= (round 2.3) 2))
+  (deftest "round produces int" (assert (integer? (round 2.3))))
+  (deftest
+    "floor of int passthrough"
+    (assert= (floor 5) 5))
+  (deftest "floor of int stays int" (assert (integer? (floor 5)))))
+
+;; --------------------------------------------------------------------------
+;; parse-number distinguishes int vs float strings
+;; --------------------------------------------------------------------------
+
+(defsuite
+  "numeric-tower:parse-number"
+  (deftest
+    "parse-number int string"
+    (assert= (parse-number "42") 42))
+  (deftest
+    "parse-number int is integer?"
+    (assert (integer? (parse-number "42"))))
+  (deftest "parse-number 3.14" (assert= (parse-number "3.14") 3.14))
+  (deftest
+    "parse-number float is float?"
+    (assert (float? (parse-number "3.14"))))
+  (deftest
+    "parse-number 1.5 is float?"
+    (assert (float? (parse-number "1.5"))))
+  (deftest
+    "parse-number negative int"
+    (assert= (parse-number "-5") -5))
+  (deftest
+    "parse-number negative int is integer?"
+    (assert (integer? (parse-number "-5"))))
+  (deftest "parse-int returns integer" (assert (integer? (parse-int "7"))))
+  (deftest "parse-int value" (assert= (parse-int "7") 7)))
+
+;; --------------------------------------------------------------------------
+;; Equality across numeric types
+;; --------------------------------------------------------------------------
+
+(defsuite
+  "numeric-tower:equality"
+  (deftest "int = same int" (assert= 5 5))
+  (deftest
+    "int = float eq"
+    (assert (= 1 (exact->inexact 1))))
+  (deftest
+    "float = int eq"
+    (assert (= (exact->inexact 1) 1)))
+  (deftest "int != different int" (assert (!= 1 2)))
+  (deftest "int < float" (assert (< 1 1.5)))
+  (deftest "float > int" (assert (> 2.5 2)))
+  (deftest "int <= float" (assert (<= 2 2.5)))
+  (deftest "int >= int" (assert (>= 3 3))))
+
+;; --------------------------------------------------------------------------
+;; mod / remainder / modulo with integers
+;; --------------------------------------------------------------------------
+
+(defsuite
+  "numeric-tower:modulo"
+  (deftest
+    "mod int int = int"
+    (assert (integer? (mod 10 3))))
+  (deftest "mod value" (assert= (mod 10 3) 1))
+  (deftest
+    "remainder int int = int"
+    (assert (integer? (remainder 10 3))))
+  (deftest
+    "remainder value"
+    (assert= (remainder 10 3) 1)))
+
+;; --------------------------------------------------------------------------
+;; min / max with mixed types
+;; --------------------------------------------------------------------------
+
+(defsuite
+  "numeric-tower:min-max"
+  (deftest "min two ints" (assert= (min 3 7) 3))
+  (deftest
+    "min int result type"
+    (assert (integer? (min 3 7))))
+  (deftest "max two ints" (assert= (max 3 7) 7))
+  (deftest "min with float" (assert= (min 3 2.5) 2.5))
+  (deftest "max with float" (assert= (max 3 3.5) 3.5)))
+
+;; --------------------------------------------------------------------------
+;; str rendering of int vs float
+;; --------------------------------------------------------------------------
+
+(defsuite
+  "numeric-tower:stringify"
+  (deftest "str of int" (assert= (str 42) "42"))
+  (deftest "str of negative int" (assert= (str -5) "-5"))
+  (deftest "str of 3.14" (assert= (str 3.14) "3.14"))
+  (deftest "str of 1.5" (assert= (str 1.5) "1.5")))