diff --git a/runtime/wasm/nat.wat b/runtime/wasm/nat.wat
new file mode 100644
index 00000000..5f3cb55b
--- /dev/null
+++ b/runtime/wasm/nat.wat
@@ -0,0 +1,523 @@
+;; Wasm_of_ocaml runtime support
+;; http://www.ocsigen.org/js_of_ocaml/
+;;
+;; This program is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU Lesser General Public License as published by
+;; the Free Software Foundation, with linking exception;
+;; either version 2.1 of the License, or (at your option) any later version.
+;;
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU Lesser General Public License for more details.
+;;
+;; You should have received a copy of the GNU Lesser General Public License
+;; along with this program; if not, write to the Free Software
+;; Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+
+(module
+   (func (export "initialize_nat") (param (ref eq)) (result (ref eq))
+      (ref.i31 (i32.const 0)))
+
+   (func (export "create_nat") (param (ref eq)) (result (ref eq))
+      (ref.i31 (i32.const 0)))
+
+   (func (export "set_to_zero_nat")
+      (param (ref eq)) (param (ref eq)) (param (ref eq)) (result (ref eq))
+      (ref.i31 (i32.const 0)))
+
+   (func (export "set_digit_nat")
+      (param (ref eq)) (param (ref eq)) (param (ref eq)) (result (ref eq))
+      (ref.i31 (i32.const 0)))
+
+   (func (export "incr_nat")
+      (param (ref eq)) (param (ref eq)) (param (ref eq)) (param (ref eq))
+      (result (ref eq))
+      (ref.i31 (i32.const 1)))
+
+(;
+   (func (export "incr_nat")
+      (param $nat (ref eq)) (param $vofs (ref eq)) (param $vlen (ref eq))
+      (param $carry_in (ref eq)) (result (ref eq))
+      (local $data (ref $data))
+      (local $carry i32) (local $i i32) (local $ofs i32) (local $len i32)
+      (local $x i32)
+      (local.set $data
+         (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat))))
+      (local.set $carry (i31.get_s (ref.cast (ref i31) (local.get $carry_in))))
+      (local.set $ofs (i31.get_s (ref.cast (ref i31) (local.get $vofs))))
+      (local.set $len (i31.get_s (ref.cast (ref i31) (local.get $vlen))))
+      (if (i32.eqz (local.get $carry))
+         (then (return (ref.i31 (i32.const 0)))))
+      (loop $loop
+         (if (i32.lt_s (local.get $i) (local.get $len))
+            (then
+               (local.set $x
+                  (i32.add
+                     (array.get $data (local.get $data) (local.get $ofs))
+                     (i32.const 1)))
+               (array.set $data (local.get $data) (local.get $ofs)
+                  (local.get $x))
+               (if (local.get $x)
+                  (then
+                     (return (ref.i31 (i32.const 0)))))
+               (local.set $ofs (i32.add (local.get $ofs) (i32.const 1)))
+               (local.set $i (i32.add (local.get $i) (i32.const 1)))
+               (br $loop))))
+      (ref.i31 (i32.const 1)))
+
+   (func (export "decr_nat")
+      (param $nat (ref eq)) (param $vofs (ref eq)) (param $vlen (ref eq))
+      (param $carry_in (ref eq)) (result (ref eq))
+      (local $data (ref $data))
+      (local $carry i32) (local $i i32) (local $ofs i32) (local $len i32)
+      (local $x i32)
+      (local.set $data
+         (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat))))
+      (local.set $carry (i31.get_s (ref.cast (ref i31) (local.get $carry_in))))
+      (local.set $ofs (i31.get_s (ref.cast (ref i31) (local.get $vofs))))
+      (local.set $len (i31.get_s (ref.cast (ref i31) (local.get $vlen))))
+      (if (i32.eqz (local.get $carry))
+         (then (return (ref.i31 (i32.const 0)))))
+      (loop $loop
+         (if (i32.lt_s (local.get $i) (local.get $len))
+            (then
+               (local.set $x
+                  (array.get $data (local.get $data) (local.get $ofs)))
+               (array.set $data (local.get $data) (local.get $ofs)
+                  (i32.sub (local.get $x) (i32.const 1)))
+               (if (local.get $x)
+                  (then
+                     (return (ref.i31 (i32.const 0)))))
+               (local.set $ofs (i32.add (local.get $ofs) (i32.const 1)))
+               (local.set $i (i32.add (local.get $i) (i32.const 1)))
+               (br $loop))))
+      (ref.i31 (i32.const 1)))
+
+   (func (export "set_digit_nat")
+      (param $nat (ref eq)) (param $ofs (ref eq)) (param $digit (ref eq))
+      (result (ref eq))
+      (array.set $data
+         (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat)))
+         (i31.get_s (ref.cast (ref i31) (local.get $ofs)))
+         (i31.get_s (ref.cast (ref i31) (local.get $digit))))
+      (ref.i31 (i32.const 0)))
+
+   (func (export "set_digit_nat_native")
+      (param $nat (ref eq)) (param $ofs (ref eq)) (param $digit (ref eq))
+      (result (ref eq))
+      (array.set $data
+         (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat)))
+         (i31.get_s (ref.cast (ref i31) (local.get $ofs)))
+         (call $Nativeint_val (local.get $digit)))
+      (ref.i31 (i32.const 0)))
+
+   (func (export "nth_digit_nat")
+      (param $nat (ref eq)) (param $ofs (ref eq)) (result (ref eq))
+      (ref.i31
+         (array.get $data
+            (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat)))
+            (i31.get_s (ref.cast (ref i31) (local.get $ofs))))))
+
+   (func (export "nth_digit_nat_native")
+      (param $nat (ref eq)) (param $ofs (ref eq)) (result (ref eq))
+      (call $caml_copy_nativeint
+         (array.get $data
+            (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat)))
+            (i31.get_s (ref.cast (ref i31) (local.get $ofs))))))
+
+   (func (export "is_digit_zero")
+      (param $nat (ref eq)) (param $ofs (ref eq)) (result (ref eq))
+      (ref.i31
+         (i32.eqz
+            (array.get $data
+               (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat)))
+               (i31.get_s (ref.cast (ref i31) (local.get $ofs)))))))
+
+   (func (export "num_leading_zero_bits_in_digit")
+      (param $nat (ref eq)) (param $ofs (ref eq)) (result (ref eq))
+      (ref.i31
+         (i32.clz
+            (array.get $data
+               (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat)))
+               (i31.get_s (ref.cast (ref i31) (local.get $ofs)))))))
+
+   (func (export "is_digit_odd")
+      (param $nat (ref eq)) (param $ofs (ref eq)) (result (ref eq))
+      (ref.i31
+         (i32.and (i32.const 1)
+            (array.get $data
+               (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat)))
+               (i31.get_s (ref.cast (ref i31) (local.get $ofs)))))))
+
+   (func (export "is_digit_int")
+      (param $nat (ref eq)) (param $ofs (ref eq)) (result (ref eq))
+      (ref.i31
+         (i32.ge_u (i32.const 0x40000000)
+            (array.get $data
+               (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat)))
+               (i31.get_s (ref.cast (ref i31) (local.get $ofs)))))))
+
+   (func (export "set_to_zero_nat")
+      (param $nat (ref eq)) (param $ofs (ref eq)) (param $len (ref eq))
+      (result (ref eq))
+      (array.fill $data
+         (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat)))
+         (i31.get_s (ref.cast (ref i31) (local.get $ofs)))
+         (i32.const 0)
+         (i31.get_s (ref.cast (ref i31) (local.get $len))))
+      (ref.i31 (i32.const 0)))
+
+   (func (export "blit_nat")
+      (param $nat1 (ref eq)) (param $ofs1 (ref eq))
+      (param $nat2 (ref eq)) (param $ofs2 (ref eq))
+      (param $len (ref eq)) (result (ref eq))
+      (array.copy $data $data
+         (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat1)))
+         (i31.get_s (ref.cast (ref i31) (local.get $ofs1)))
+         (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat2)))
+         (i31.get_s (ref.cast (ref i31) (local.get $ofs2)))
+         (i31.get_s (ref.cast (ref i31) (local.get $len))))
+      (ref.i31 (i32.const 0)))
+
+   (func (export "num_digits_nat")
+      (param $nat (ref eq)) (param $vofs (ref eq)) (param $vlen (ref eq))
+      (result (ref eq))
+      (local $ofs i32) (local $len i32) (local $data (ref $data))
+      (local.set $ofs (i31.get_s (ref.cast (ref i31) (local.get $vofs))))
+      (local.set $len (i31.get_s (ref.cast (ref i31) (local.get $vlen))))
+      (local.set $data
+         (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat))))
+      (local.set $ofs
+         (i32.add (local.get $ofs) (i32.sub (local.get $len) (i32.const 1))))
+      (loop $loop
+         (if (i32.eqz (local.get $len)) (then (return (ref.i31 (i32.const 1)))))
+         (if (array.get $data (local.get $data) (local.get $ofs))
+            (then (return (ref.i31 (local.get $len)))))
+         (local.set $len (i32.sub (local.get $len) (i32.const 1)))
+         (local.set $ofs (i32.sub (local.get $ofs) (i32.const 1)))
+         (br $loop)))
+
+   (func (export "compare_digits_nat")
+      (param $nat1 (ref eq)) (param $ofs1 (ref eq))
+      (param $nat2 (ref eq)) (param $ofs2 (ref eq)) (result (ref eq))
+      (local $d1 i32) (local $d2 i32)
+      (local.set $d1
+         (array.get $data
+            (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat1)))
+            (i31.get_s (ref.cast (ref i31) (local.get $ofs1)))))
+      (local.set $d2
+         (array.get $data
+            (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat2)))
+            (i31.get_s (ref.cast (ref i31) (local.get $ofs2)))))
+      (if (i32.gt_u (local.get $d1) (local.get $d2))
+         (then (return (ref.i31 (i32.const 1)))))
+      (if (i32.lt_u (local.get $d1) (local.get $d2))
+         (then (return (ref.i31 (i32.const -1)))))
+      (ref.i31 (i32.const 0)))
+
+   (func (export "compare_nat")
+      (param $nat1 (ref eq)) (param $vofs1 (ref eq)) (param $vlen1 (ref eq))
+      (param $nat2 (ref eq)) (param $vofs2 (ref eq)) (param $vlen2 (ref eq))
+      (result (ref eq))
+      (local $ofs1 i32) (local $len1 i32) (local $data1 (ref $data))
+      (local $ofs2 i32) (local $len2 i32) (local $data2 (ref $data))
+      (local $d1 i32) (local $d2 i32)
+      (local.set $ofs1 (i31.get_s (ref.cast (ref i31) (local.get $vofs1))))
+      (local.set $len1 (i31.get_s (ref.cast (ref i31) (local.get $vlen1))))
+      (local.set $data1
+         (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat1))))
+      (local.set $ofs1
+         (i32.add (local.get $ofs1) (i32.sub (local.get $len1) (i32.const 1))))
+      (local.set $ofs2 (i31.get_s (ref.cast (ref i31) (local.get $vofs2))))
+      (local.set $len2 (i31.get_s (ref.cast (ref i31) (local.get $vlen2))))
+      (local.set $data2
+         (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat2))))
+      (local.set $ofs2
+         (i32.add (local.get $ofs2) (i32.sub (local.get $len2) (i32.const 1))))
+      (loop $loop
+         (if (local.get $len1)
+            (then
+               (if (i32.eqz
+                      (array.get $data (local.get $data1) (local.get $ofs1)))
+                  (then
+                     (local.set $len1 (i32.sub (local.get $len1) (i32.const 1)))
+                     (local.set $ofs1 (i32.sub (local.get $ofs1) (i32.const 1)))
+                     (br $loop))))))
+      (loop $loop
+         (if (local.get $len2)
+            (then
+               (if (i32.eqz
+                      (array.get $data (local.get $data2) (local.get $ofs2)))
+                  (then
+                     (local.set $len2 (i32.sub (local.get $len2) (i32.const 1)))
+                     (local.set $ofs2 (i32.sub (local.get $ofs2) (i32.const 1)))
+                     (br $loop))))))
+      (if (i32.gt_u (local.get $len1) (local.get $len2))
+         (then (return (ref.i31 (i32.const 1)))))
+      (if (i32.lt_u (local.get $len2) (local.get $len1))
+         (then (return (ref.i31 (i32.const -1)))))
+      (loop $loop
+         (if (local.get $len1)
+            (then
+               (local.set $len1 (i32.sub (local.get $len1) (i32.const 1)))
+               (local.set $d1
+                  (array.get $data (local.get $data1) (local.get $ofs1)))
+               (local.set $d2
+                  (array.get $data (local.get $data2) (local.get $ofs2)))
+               (if (i32.gt_u (local.get $d1) (local.get $d2))
+                  (then (return (ref.i31 (i32.const 1)))))
+               (if (i32.lt_u (local.get $d1) (local.get $d2))
+                  (then (return (ref.i31 (i32.const -1)))))
+               (local.set $ofs1 (i32.sub (local.get $ofs1) (i32.const 1)))
+               (local.set $ofs2 (i32.sub (local.get $ofs2) (i32.const 1)))
+               (br $loop))))
+      (ref.i31 (i32.const 0)))
+
+   (func (export "mult_digit_nat")
+      (param $nat1 (ref eq)) (param $vofs1 (ref eq)) (param $vlen1 (ref eq))
+      (param $nat2 (ref eq)) (param $vofs2 (ref eq)) (param $vlen2 (ref eq))
+      (param $nat3 (ref eq)) (param $vofs3 (ref eq)) (result (ref eq))
+      (local $ofs1 i32) (local $len1 i32) (local $data1 (ref $data))
+      (local $ofs2 i32) (local $len2 i32) (local $data2 (ref $data))
+      (local $i i32) (local $d i64) (local $x i64) (local $carry i64)
+      (local $y i32)
+      (local.set $d
+         (i64.extend_i32_u
+            (array.get $data
+               (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat3)))
+               (i31.get_s (ref.cast (ref i31) (local.get $vofs3))))))
+      (local.set $ofs1 (i31.get_s (ref.cast (ref i31) (local.get $vofs1))))
+      (local.set $len1 (i31.get_s (ref.cast (ref i31) (local.get $vlen1))))
+      (local.set $data1
+         (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat1))))
+      (local.set $ofs2 (i31.get_s (ref.cast (ref i31) (local.get $vofs2))))
+      (local.set $len2 (i31.get_s (ref.cast (ref i31) (local.get $vlen2))))
+      (local.set $data2
+         (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat2))))
+      (local.set $len1 (i32.sub (local.get $len1) (local.get $len2)))
+      (loop $loop
+         (if (i32.lt_s (local.get $i) (local.get $len2))
+            (then
+               (local.set $x
+                  (i64.add
+                     (i64.add (local.get $carry)
+                        (i64.extend_i32_u
+                           (array.get $data (local.get $data1)
+                              (local.get $ofs1))))
+                     (i64.mul (local.get $d)
+                        (i64.extend_i32_u
+                           (array.get $data (local.get $data2)
+                              (local.get $ofs2))))))
+               (array.set $data (local.get $data1) (local.get $ofs1)
+                  (i32.wrap_i64 (local.get $x)))
+               (local.set $carry (i64.shr_u (local.get $x) (i64.const 32)))
+               (local.set $i (i32.add (local.get $i) (i32.const 1)))
+               (local.set $ofs1 (i32.add (local.get $ofs1) (i32.const 1)))
+               (local.set $ofs2 (i32.add (local.get $ofs2) (i32.const 1)))
+               (br $loop))))
+      (if (i32.eqz (local.get $len1))
+         (then (return (ref.i31 (i32.wrap_i64 (local.get $carry))))))
+      (local.set $x
+         (i64.add (local.get $carry)
+            (i64.extend_i32_u
+               (array.get $data (local.get $data1) (local.get $ofs1)))))
+      (array.set $data (local.get $data1) (local.get $ofs1)
+         (i32.wrap_i64 (local.get $x)))
+      (local.set $carry (i64.shr_u (local.get $x) (i64.const 32)))
+      (local.set $len1 (i32.sub (local.get $len1) (i32.const 1)))
+      (if (i64.eqz (local.get $carry)) (then (return (ref.i31 (i32.const 0)))))
+      (if (i32.eqz (local.get $len1))
+         (then (return (ref.i31 (i32.wrap_i64 (local.get $carry))))))
+      (local.set $ofs1 (i32.add (local.get $ofs1) (i32.const 1)))
+      (loop $loop
+         (local.set $y
+            (i32.add
+               (array.get $data (local.get $data1) (local.get $ofs1))
+                  (i32.const 1)))
+         (array.set $data (local.get $data1) (local.get $ofs1) (local.get $y))
+         (if (local.get $y) (then (return (ref.i31 (i32.const 0)))))
+         (local.set $len1 (i32.sub (local.get $len1) (i32.const 1)))
+         (local.set $ofs1 (i32.add (local.get $ofs1) (i32.const 1)))
+         (if (local.get $len1) (then (br $loop))))
+      (ref.i31 (i32.const 1)))
+
+   (data $mult_nat "mult_nat")
+
+   (func (export "mult_nat")
+      (param $nat1 (ref eq)) (param $vofs1 (ref eq)) (param $vlen1 (ref eq))
+      (param $nat2 (ref eq)) (param $vofs2 (ref eq)) (param $vlen2 (ref eq))
+      (param $nat3 (ref eq)) (param $vofs3 (ref eq)) (param $vlen3 (ref eq))
+      (result (ref eq))
+      ;; ZZZ
+      (call $log_str
+         (array.new_data $string $mult_nat (i32.const 0) (i32.const 8)))
+      (unreachable))
+
+   (data $square_nat "square_nat")
+
+   (func (export "square_nat")
+      (param $nat1 (ref eq)) (param $vofs1 (ref eq)) (param $vlen1 (ref eq))
+      (param $nat2 (ref eq)) (param $vofs2 (ref eq)) (param $vlen2 (ref eq))
+      (result (ref eq))
+      ;; ZZZ
+      (call $log_str
+         (array.new_data $string $square_nat (i32.const 0) (i32.const 10)))
+      (unreachable))
+
+   (data $shift_left_nat "shift_left_nat")
+
+   (func (export "shift_left_nat")
+      (param $nat1 (ref eq)) (param $vofs1 (ref eq)) (param $vlen1 (ref eq))
+      (param $nat2 (ref eq)) (param $vofs2 (ref eq)) (param $vnbits (ref eq))
+      (result (ref eq))
+      ;; ZZZ
+      (call $log_str
+         (array.new_data $string $shift_left_nat (i32.const 0) (i32.const 14)))
+      (unreachable))
+
+   (data $shift_right_nat "shift_right_nat")
+
+   (func (export "shift_right_nat")
+      (param $nat1 (ref eq)) (param $vofs1 (ref eq)) (param $vlen1 (ref eq))
+      (param $nat2 (ref eq)) (param $vofs2 (ref eq)) (param $vnbits (ref eq))
+      (result (ref eq))
+      ;; ZZZ
+      (call $log_str
+         (array.new_data $string $shift_right_nat (i32.const 0) (i32.const 15)))
+      (unreachable))
+
+   (data $div_digit_nat "div_digit_nat")
+
+   (func (export "div_digit_nat")
+      (param $natq (ref eq)) (param $ofsq (ref eq))
+      (param $natr (ref eq)) (param $ofsr (ref eq))
+      (param $nat1 (ref eq)) (param $ofs1 (ref eq)) (param $len (ref eq))
+      (param $nat2 (ref eq)) (param $ofs2 (ref eq)) (result (ref eq))
+      ;; ZZZ
+      (call $log_str
+         (array.new_data $string $div_digit_nat (i32.const 0) (i32.const 13)))
+      (unreachable))
+
+   (data $div_nat "div_nat")
+
+   (func (export "div_nat")
+      (param $nat1 (ref eq)) (param $vofs1 (ref eq)) (param $vlen1 (ref eq))
+      (param $nat2 (ref eq)) (param $vofs2 (ref eq)) (param $vlen2 (ref eq))
+      (result (ref eq))
+      ;; ZZZ
+      (call $log_str
+         (array.new_data $string $div_nat (i32.const 0) (i32.const 7)))
+      (unreachable))
+
+   (data $add_nat "add_nat")
+
+   (func (export "add_nat")
+      (param $nat1 (ref eq)) (param $vofs1 (ref eq)) (param $vlen1 (ref eq))
+      (param $nat2 (ref eq)) (param $vofs2 (ref eq)) (param $vlen2 (ref eq))
+      (param $carry_in (ref eq))
+      (result (ref eq))
+      ;; ZZZ
+      (call $log_str
+         (array.new_data $string $add_nat (i32.const 0) (i32.const 7)))
+      (unreachable))
+
+   (data $sub_nat "sub_nat")
+
+   (func (export "sub_nat")
+      (param $nat1 (ref eq)) (param $vofs1 (ref eq)) (param $vlen1 (ref eq))
+      (param $nat2 (ref eq)) (param $vofs2 (ref eq)) (param $vlen2 (ref eq))
+      (param $carry_in (ref eq))
+      (result (ref eq))
+      ;; ZZZ
+      (call $log_str
+         (array.new_data $string $sub_nat (i32.const 0) (i32.const 7)))
+      (unreachable))
+
+   (data $complement_nat "complement_nat")
+
+   (func (export "complement_nat")
+      (param $nat (ref eq)) (param $vofs (ref eq)) (param $vlen (ref eq))
+      (result (ref eq))
+      ;; ZZZ
+      (call $log_str
+         (array.new_data $string $complement_nat (i32.const 0) (i32.const 14)))
+      (unreachable))
+
+   (func (export "land_digit_nat")
+      (param $nat1 (ref eq)) (param $vofs1 (ref eq))
+      (param $nat2 (ref eq)) (param $vofs2 (ref eq))
+      (result (ref eq))
+      (local $ofs1 i32) (local $data1 (ref $data))
+      (local $ofs2 i32) (local $data2 (ref $data))
+      (local.set $data1
+         (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat1))))
+      (local.set $ofs1 (i31.get_s (ref.cast (ref i31) (local.get $vofs1))))
+      (local.set $data2
+         (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat2))))
+      (local.set $ofs2 (i31.get_s (ref.cast (ref i31) (local.get $vofs2))))
+      (array.set $data (local.get $data1) (local.get $ofs1)
+         (i32.and (array.get $data (local.get $data1) (local.get $ofs1))
+            (array.get $data (local.get $data2) (local.get $ofs2))))
+      (ref.i31 (i32.const 0)))
+
+   (func (export "lxor_digit_nat")
+      (param $nat1 (ref eq)) (param $vofs1 (ref eq))
+      (param $nat2 (ref eq)) (param $vofs2 (ref eq))
+      (result (ref eq))
+      (local $ofs1 i32) (local $data1 (ref $data))
+      (local $ofs2 i32) (local $data2 (ref $data))
+      (local.set $data1
+         (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat1))))
+      (local.set $ofs1 (i31.get_s (ref.cast (ref i31) (local.get $vofs1))))
+      (local.set $data2
+         (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat2))))
+      (local.set $ofs2 (i31.get_s (ref.cast (ref i31) (local.get $vofs2))))
+      (array.set $data (local.get $data1) (local.get $ofs1)
+         (i32.xor (array.get $data (local.get $data1) (local.get $ofs1))
+            (array.get $data (local.get $data2) (local.get $ofs2))))
+      (ref.i31 (i32.const 0)))
+
+   (func (export "lor_digit_nat")
+      (param $nat1 (ref eq)) (param $vofs1 (ref eq))
+      (param $nat2 (ref eq)) (param $vofs2 (ref eq))
+      (result (ref eq))
+      (local $ofs1 i32) (local $data1 (ref $data))
+      (local $ofs2 i32) (local $data2 (ref $data))
+      (local.set $data1
+         (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat1))))
+      (local.set $ofs1 (i31.get_s (ref.cast (ref i31) (local.get $vofs1))))
+      (local.set $data2
+         (struct.get $nat $data (ref.cast (ref $nat) (local.get $nat2))))
+      (local.set $ofs2 (i31.get_s (ref.cast (ref i31) (local.get $vofs2))))
+      (array.set $data (local.get $data1) (local.get $ofs1)
+         (i32.or (array.get $data (local.get $data1) (local.get $ofs1))
+            (array.get $data (local.get $data2) (local.get $ofs2))))
+      (ref.i31 (i32.const 0)))
+
+   (data $hash_nat "hash_nat")
+
+   (func $hash_nat (param (ref eq)) (result i32)
+      ;; ZZZ
+      (call $log_str
+         (array.new_data $string $hash_nat (i32.const 0) (i32.const 8)))
+      (unreachable))
+
+   (data $serialize_nat "serialize_nat")
+
+   (func $serialize_nat
+      (param (ref eq)) (param (ref eq)) (result i32) (result i32)
+      ;; ZZZ
+      (call $log_str
+         (array.new_data $string $serialize_nat (i32.const 0) (i32.const 13)))
+      (unreachable))
+
+   (data $deserialize_nat "deserialize_nat")
+
+   (func $deserialize_nat (param (ref eq)) (result (ref eq)) (result i32)
+      ;; ZZZ
+      (call $log_str
+         (array.new_data $string $serialize_nat (i32.const 0) (i32.const 15)))
+      (unreachable))
+;)
+)