add atom support to interpreter and JS runtime

- Add OAtom type and atom/swap!/deref functions to eval backend
- Add swap_BANG_ function to JS runtime
- Simplify swap! macro to delegate to prelude/swap!
- Add _QMARK_ decoding in JS backend for ? in names
- Simplify def* name handling in JS backend
- Add @SuppressWarnings("unchecked") to Java RT

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: y2k

backend/backend_eval_functions.ml

@@ -99,7 +99,8 @@ let attach reg_val reg_fun ctx =
           | OFloat (m, f) -> OFloat ({ m with symbol }, f)
           | OBool (m, b) -> OBool ({ m with symbol }, b)
           | OLambda (m, f) -> OLambda ({ m with symbol }, f)
-          | OQuote (m, n) -> OQuote ({ m with symbol }, n))
+          | OQuote (m, n) -> OQuote ({ m with symbol }, n)
+          | OAtom (m, r) -> OAtom ({ m with symbol }, r))
       | x -> Obj.failobj __LOC__ x)
   |> reg_fun "boolean" (function
     | [ OBool (_, x) ] -> OBool (meta_empty, x)
@@ -268,3 +269,15 @@ let attach reg_val reg_fun ctx =
     | [ OLambda (_, f); OVector (_, xs) ] ->
         OVector (meta_empty, List.map (fun x -> f [ x ]) xs)
     | x -> Obj.failobj __LOC__ x)
+  |> reg_fun "atom" (function
+    | [ x ] -> OAtom (meta_empty, ref x)
+    | x -> Obj.failobj __LOC__ x)
+  |> reg_fun "swap!" (function
+    | [ OAtom (_, r); OLambda (_, f) ] ->
+        let old_val = !r in
+        r := f [ old_val ];
+        old_val
+    | x -> Obj.failobj __LOC__ x)
+  |> reg_fun "deref" (function
+    | [ OAtom (_, r) ] -> !r
+    | x -> Obj.failobj __LOC__ x)

backend/backend_js.ml

@@ -35,7 +35,9 @@ let rec do_compile (ctx : context) = function
   | SAtom (_, x) when String.starts_with ~prefix:":" x ->
       "\"" ^ unpack_symbol x ^ "\""
   | SAtom (_, x) when not (String.starts_with ~prefix:"\"" x) ->
-      x |> String.map (fun x -> if x = '/' then '.' else x)
+      x
+      |> String.map (fun x -> if x = '/' then '.' else x)
+      |> Re.replace (Re.Pcre.re "_QMARK_" |> Re.compile) ~f:(Fun.const "?")
   | SAtom (_, x) -> x
   (* TODO: move to macro *)
   | SList (_, [ SAtom (_, "<="); a; b ]) ->
@@ -114,10 +116,9 @@ let rec do_compile (ctx : context) = function
   | SList (_, [ SAtom (_, "assoc"); map; key; value ]) ->
       Printf.sprintf "{ ...%s, [%s]: %s }" (do_compile ctx map)
         (do_compile ctx key) (do_compile ctx value)
-  | SList (_, [ SAtom (m, "def*"); name; value ]) ->
+  | SList (_, [ SAtom (m, "def*"); SAtom (_, name); value ]) ->
       let export = if m.symbol = "private" then "" else "export " in
-      Printf.sprintf "%sconst %s=%s" export (do_compile ctx name)
-        (do_compile ctx value)
+      Printf.sprintf "%sconst %s=%s" export name (do_compile ctx value)
   (* let *)
   | SList (_, [ SAtom (_, "let*"); name; value ]) ->
       Printf.sprintf "const %s=%s" (do_compile ctx name) (do_compile ctx value)

core/common.ml

@@ -125,6 +125,7 @@ type obj =
   | ONil of meta
   | OLambda of meta * (obj list -> obj)
   | OQuote of meta * sexp
+  | OAtom of meta * obj ref
 [@@deriving show]
 
 module Obj = struct
@@ -294,6 +295,7 @@ module OUtils = struct
     | OQuote (_, m) -> "(quote" ^ debug_show_sexp_for_error [ m ] ^ ")"
     | OFloat _ -> failwith __LOC__
     | OLambda _ -> failwith __LOC__
+    | OAtom (_, r) -> Printf.sprintf "(atom %s)" (obj_to_string !r)
 
   let failobj loc x = Printf.sprintf "%s %s" loc (obj_to_string x) |> failwith
 
@@ -329,6 +331,7 @@ module OUtils = struct
     | OQuote (_, m) -> "(quote '" ^ debug_show_sexp_for_error [ m ] ^ "')"
     | OMap _ -> failwith "OMap"
     | OLambda _ -> failwith "OLambda"
+    | OAtom (_, r) -> Printf.sprintf "(atom %s)" (debug_obj_to_string !r)
 end
 
 module NamespaceUtils = struct

core/prelude.ml

@@ -5,6 +5,7 @@ package y2k;
 
 import java.util.*;
 
+@SuppressWarnings("unchecked")
 public class RT {
 
     public static Object hash_map_from(Object xs) {
@@ -350,6 +351,12 @@ export const re_find = (p, i) => {
     }
     return result[0];
 }
+
+export const swap_BANG_ = (atom, f) => {
+    const result = atom[0];
+    atom[0] = (result);
+    return result;
+}
 |}
 
 let java_runtime2 = {|
@@ -883,9 +890,7 @@ let prelude_js_macro = {|
 ;; Atoms
 
 (defn macro_swap! [a f]
-  (list 'do
-        (list 'assoc! a 0 (list f (list 'get a 0)))
-        (list 'get a 0)))
+  (list 'prelude/swap! a f))
 
 (defn macro_reset! [a x]
   (list 'assoc! a 0 x))

prelude/data/prelude_js_macro.clj

@@ -156,9 +156,7 @@
 ;; Atoms
 
 (defn macro_swap! [a f]
-  (list 'do
-        (list 'assoc! a 0 (list f (list 'get a 0)))
-        (list 'get a 0)))
+  (list 'prelude/swap! a f))
 
 (defn macro_reset! [a x]
   (list 'assoc! a 0 x))

prelude/data/y2k/RT.java

@@ -2,6 +2,7 @@
 
 import java.util.*;
 
+@SuppressWarnings("unchecked")
 public class RT {
 
     public static Object hash_map_from(Object xs) {

prelude/data/y2k/rt.js

@@ -16,4 +16,10 @@ export const re_find = (p, i) => {
         return null;
     }
     return result[0];
+}
+
+export const swap_BANG_ = (atom, f) => {
+    const result = atom[0];
+    atom[0] = (result);
+    return result;
 }

test/test_common.clj

@@ -11,6 +11,8 @@
 (defn- ?!- [x] x)
 
 (defn test []
+  (let [value_atom (atom 1)]
+    (assert_ __LOC__ 1 (swap! value_atom (fn [^int x] (+ x 2)))))
   (assert_ __LOC__ 1 (?!- 1))
   (assert_ __LOC__ [] (filter (fn [_] false) [1 2]))
   (assert_ __LOC__ ["1" "2"] (map (fn [x] (str x)) [1 2]))