Compiler: dict destructuring in let, paren-aware library stripping — 31/31 sxbc

compile-let now handles dict destructuring patterns:
(let {:key1 var1 :key2 var2} source body). This unblocked core-signals.sx
(deref uses dict destructuring) which was the sole bytecode skip.

Rewrote stripLibraryWrapper from line-based to paren-aware extraction.
The old regex missed (define-library on its own line (no trailing space),
silently passing the full wrapper to the compiler.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

hosts/ocaml/browser/compile-modules.js

@@ -126,36 +126,102 @@ for (const file of FILES) {
 // ---------------------------------------------------------------------------
 
 function stripLibraryWrapper(source) {
-  // Line-based stripping: unwrap (define-library ... (begin BODY)), keep (import ...).
+  // Paren-aware stripping: find (begin ...) inside (define-library ...), extract body.
-  const lines = source.split('\n');
+  // Keep top-level (import ...) forms outside the define-library.
-  const result = [];
-  let skip = false;     // inside header region (define-library, export)
 
-  for (let i = 0; i < lines.length; i++) {
+  // Find (define-library at the start
-    const line = lines[i];
+  const dlMatch = source.match(/^[\s\S]*?\(define-library\b/);
-    const trimmed = line.trim();
+  if (!dlMatch) return source; // no define-library, return as-is
 
-    // Skip (define-library ...) header lines until (begin
+  // Find the (begin that opens the body — skip past (export ...) using paren counting
-    if (trimmed.startsWith('(define-library ')) { skip = true; continue; }
+  const afterDL = dlMatch[0].length;
-    if (skip && trimmed.startsWith('(export')) { continue; }
+  let pos = afterDL;
-    if (skip && trimmed.match(/^\(begin/)) { skip = false; continue; }
+  let foundBegin = -1;
-    if (skip) continue;
 
-    // Skip closing )) of define-library — line is just ) or )) optionally with comments
+  while (pos < source.length) {
-    if (trimmed.match(/^\)+(\s*;.*)?$/)) {
+    // Skip whitespace and comments
-      // Check if this is the end-of-define-library closer (only `)` chars + optional comment)
+    while (pos < source.length && /[\s]/.test(source[pos])) pos++;
-      // vs a regular body closer like `    )` inside a nested form
+    if (pos >= source.length) break;
-      // Only skip if at column 0 (not indented = top-level closer)
+    if (source[pos] === ';') { // skip comment line
-      if (line.match(/^\)/)) continue;
+      while (pos < source.length && source[pos] !== '\n') pos++;
+      continue;
     }
 
-    // Skip standalone comments that are just structural markers
+    // Check for (begin
-    if (trimmed.match(/^;;\s*(end define-library|Re-export)/)) continue;
+    if (source.startsWith('(begin', pos)) {
+      foundBegin = pos;
+      break;
+    }
 
-    result.push(line);
+    // Skip balanced sexp (the library name and export list)
+    if (source[pos] === '(') {
+      let depth = 1;
+      pos++;
+      while (pos < source.length && depth > 0) {
+        if (source[pos] === '(') depth++;
+        else if (source[pos] === ')') depth--;
+        else if (source[pos] === '"') { // skip strings
+          pos++;
+          while (pos < source.length && source[pos] !== '"') {
+            if (source[pos] === '\\') pos++;
+            pos++;
+          }
+        } else if (source[pos] === ';') { // skip comments
+          while (pos < source.length && source[pos] !== '\n') pos++;
+          continue;
+        }
+        pos++;
+      }
+    } else {
+      // Skip atom
+      while (pos < source.length && !/[\s()]/.test(source[pos])) pos++;
+    }
   }
 
-  return result.join('\n');
+  if (foundBegin === -1) return source; // no (begin found
+
+  // Find the body inside (begin ...) — skip "(begin" + optional whitespace
+  let bodyStart = foundBegin + 6; // len("(begin") = 6
+  // Skip optional newline/whitespace after (begin
+  while (bodyStart < source.length && /[\s]/.test(source[bodyStart])) bodyStart++;
+
+  // Find matching close of (begin ...) using paren counting from foundBegin
+  pos = foundBegin + 1; // after opening (
+  let depth = 1;
+  while (pos < source.length && depth > 0) {
+    if (source[pos] === '(') depth++;
+    else if (source[pos] === ')') depth--;
+    else if (source[pos] === '"') {
+      pos++;
+      while (pos < source.length && source[pos] !== '"') {
+        if (source[pos] === '\\') pos++;
+        pos++;
+      }
+    } else if (source[pos] === ';') {
+      while (pos < source.length && source[pos] !== '\n') pos++;
+      continue;
+    }
+    if (depth > 0) pos++;
+  }
+  const beginClose = pos; // position of closing ) for (begin ...)
+
+  // Extract body (everything between (begin and its closing paren)
+  const body = source.slice(bodyStart, beginClose);
+
+  // Find any (import ...) forms AFTER the define-library
+  // The define-library's closing paren is right after begin's
+  let dlClose = beginClose + 1;
+  while (dlClose < source.length && source[dlClose] !== ')') {
+    if (source[dlClose] === ';') {
+      while (dlClose < source.length && source[dlClose] !== '\n') dlClose++;
+    }
+    dlClose++;
+  }
+  dlClose++; // past the closing )
+
+  const afterDLForm = source.slice(dlClose);
+
+  return body + '\n' + afterDLForm;
 }
 
 // Compile each module (stripped of define-library/import wrappers)

lib/compiler.sx

@@ -589,24 +589,64 @@
                   (list (list (make-symbol loop-name) lambda-expr)))
                 (call-expr (cons (make-symbol loop-name) inits)))
               (compile-letrec em (list letrec-bindings call-expr) scope tail?)))
-          (let
+          (if
-            ((bindings (first args))
+            (dict? (first args))
-              (body (rest args))
+            (let
-              (let-scope (make-scope scope)))
+              ((pattern (first args))
-            (dict-set! let-scope "next-slot" (get scope "next-slot"))
+                (source-expr (nth args 1))
-            (for-each
+                (body (slice args 2))
-              (fn
+                (let-scope (make-scope scope)))
-                (binding)
+              (dict-set! let-scope "next-slot" (get scope "next-slot"))
-                (let
+              (compile-expr em source-expr let-scope false)
-                  ((name (if (= (type-of (first binding)) "symbol") (symbol-name (first binding)) (first binding)))
+              (let
-                    (value (nth binding 1)))
+                ((temp-slot (scope-define-local let-scope "__dict_src")))
-                  (compile-expr em value let-scope false)
+                (emit-op em 17)
+                (emit-byte em temp-slot)
+                (for-each
+                  (fn
+                    (k)
+                    (let
+                      ((var-name (get pattern k))
+                        (key-str
+                          (if
+                            (= (type-of k) "keyword")
+                            (keyword-name k)
+                            (str k))))
+                      (emit-op em 16)
+                      (emit-byte em temp-slot)
+                      (let
+                        ((key-idx (pool-add (get em "pool") key-str)))
+                        (emit-op em 2)
+                        (emit-u16 em key-idx))
+                      (let
+                        ((get-idx (pool-add (get em "pool") "get")))
+                        (emit-op em 10)
+                        (emit-u16 em get-idx)
+                        (emit-byte em 2))
+                      (let
+                        ((slot (scope-define-local let-scope (if (= (type-of var-name) "symbol") (symbol-name var-name) var-name))))
+                        (emit-op em 17)
+                        (emit-byte em slot))))
+                  (keys pattern))
+                (compile-begin em body let-scope tail?)))
+            (let
+              ((bindings (first args))
+                (body (rest args))
+                (let-scope (make-scope scope)))
+              (dict-set! let-scope "next-slot" (get scope "next-slot"))
+              (for-each
+                (fn
+                  (binding)
                   (let
-                    ((slot (scope-define-local let-scope name)))
+                    ((name (if (= (type-of (first binding)) "symbol") (first binding) (make-symbol (first binding))))
-                    (emit-op em 17)
+                      (value (nth binding 1)))
-                    (emit-byte em slot))))
+                    (compile-expr em value let-scope false)
-              bindings)
+                    (let
-            (compile-begin em body let-scope tail?)))))
+                      ((slot (scope-define-local let-scope (symbol-name name))))
+                      (emit-op em 17)
+                      (emit-byte em slot))))
+                bindings)
+              (compile-begin em body let-scope tail?))))))
     (define
       compile-letrec
       (fn

shared/static/wasm/sx/compiler.sx

@@ -589,24 +589,64 @@
                   (list (list (make-symbol loop-name) lambda-expr)))
                 (call-expr (cons (make-symbol loop-name) inits)))
               (compile-letrec em (list letrec-bindings call-expr) scope tail?)))
-          (let
+          (if
-            ((bindings (first args))
+            (dict? (first args))
-              (body (rest args))
+            (let
-              (let-scope (make-scope scope)))
+              ((pattern (first args))
-            (dict-set! let-scope "next-slot" (get scope "next-slot"))
+                (source-expr (nth args 1))
-            (for-each
+                (body (slice args 2))
-              (fn
+                (let-scope (make-scope scope)))
-                (binding)
+              (dict-set! let-scope "next-slot" (get scope "next-slot"))
-                (let
+              (compile-expr em source-expr let-scope false)
-                  ((name (if (= (type-of (first binding)) "symbol") (symbol-name (first binding)) (first binding)))
+              (let
-                    (value (nth binding 1)))
+                ((temp-slot (scope-define-local let-scope "__dict_src")))
-                  (compile-expr em value let-scope false)
+                (emit-op em 17)
+                (emit-byte em temp-slot)
+                (for-each
+                  (fn
+                    (k)
+                    (let
+                      ((var-name (get pattern k))
+                        (key-str
+                          (if
+                            (= (type-of k) "keyword")
+                            (keyword-name k)
+                            (str k))))
+                      (emit-op em 16)
+                      (emit-byte em temp-slot)
+                      (let
+                        ((key-idx (pool-add (get em "pool") key-str)))
+                        (emit-op em 2)
+                        (emit-u16 em key-idx))
+                      (let
+                        ((get-idx (pool-add (get em "pool") "get")))
+                        (emit-op em 10)
+                        (emit-u16 em get-idx)
+                        (emit-byte em 2))
+                      (let
+                        ((slot (scope-define-local let-scope (if (= (type-of var-name) "symbol") (symbol-name var-name) var-name))))
+                        (emit-op em 17)
+                        (emit-byte em slot))))
+                  (keys pattern))
+                (compile-begin em body let-scope tail?)))
+            (let
+              ((bindings (first args))
+                (body (rest args))
+                (let-scope (make-scope scope)))
+              (dict-set! let-scope "next-slot" (get scope "next-slot"))
+              (for-each
+                (fn
+                  (binding)
                   (let
-                    ((slot (scope-define-local let-scope name)))
+                    ((name (if (= (type-of (first binding)) "symbol") (first binding) (make-symbol (first binding))))
-                    (emit-op em 17)
+                      (value (nth binding 1)))
-                    (emit-byte em slot))))
+                    (compile-expr em value let-scope false)
-              bindings)
+                    (let
-            (compile-begin em body let-scope tail?)))))
+                      ((slot (scope-define-local let-scope (symbol-name name))))
+                      (emit-op em 17)
+                      (emit-byte em slot))))
+                bindings)
+              (compile-begin em body let-scope tail?))))))
     (define
       compile-letrec
       (fn

shared/static/wasm/sx/signals.sxbc

@@ -1,3 +1,3 @@
 (sxbc 1 "232c1519553b1d5f"
   (code
-    :constants ({:library (sx dom) :op "import"} {:library (sx browser) :op "import"} "with-marsh-scope" {:upvalue-count 0 :arity 2 :constants ("list" "with-island-scope" {:upvalue-count 1 :arity 1 :constants ("append!") :bytecode (18 0 16 0 52 0 0 2 50)} "dom-set-data" "sx-marsh-disposers") :bytecode (52 0 0 0 17 2 20 1 0 51 2 0 1 2 16 1 48 2 5 20 3 0 16 0 1 4 0 16 2 49 3 50)} "dispose-marsh-scope" {:upvalue-count 0 :arity 1 :constants ("dom-get-data" "sx-marsh-disposers" "for-each" {:upvalue-count 0 :arity 1 :constants ("cek-call") :bytecode (16 0 2 52 0 0 2 50)} "dom-set-data") :bytecode (20 0 0 16 0 1 1 0 48 2 17 1 16 1 33 24 0 51 3 0 16 1 52 2 0 2 5 20 4 0 16 0 1 1 0 2 49 3 32 1 0 2 50)} "emit-event" {:upvalue-count 0 :arity 3 :constants ("dom-dispatch") :bytecode (20 0 0 16 0 16 1 16 2 49 3 50)} "on-event" {:upvalue-count 0 :arity 3 :constants ("dom-on") :bytecode (20 0 0 16 0 16 1 16 2 49 3 50)} "bridge-event" {:upvalue-count 0 :arity 4 :constants ("effect" {:upvalue-count 4 :arity 0 :constants ("dom-on" {:upvalue-count 2 :arity 1 :constants ("event-detail" "cek-call" "list" "reset!") :bytecode (20 0 0 16 0 48 1 17 1 18 0 33 15 0 18 0 16 1 52 2 0 1 52 1 0 2 32 2 0 16 1 17 2 20 3 0 18 1 16 2 49 2 50)}) :bytecode (20 0 0 18 0 18 1 51 1 0 0 2 0 3 48 3 17 0 16 0 50)}) :bytecode (20 0 0 51 1 0 1 0 1 1 1 3 1 2 49 1 50)} "resource" {:upvalue-count 0 :arity 1 :constants ("signal" "dict" "loading" "data" "error" "promise-then" "cek-call" {:upvalue-count 1 :arity 1 :constants ("reset!" "dict" "loading" "data" "error") :bytecode (20 0 0 18 0 1 2 0 4 1 3 0 16 0 1 4 0 2 52 1 0 6 49 2 50)} {:upvalue-count 1 :arity 1 :constants ("reset!" "dict" "loading" "data" "error") :bytecode (20 0 0 18 0 1 2 0 4 1 3 0 2 1 4 0 16 0 52 1 0 6 49 2 50)}) :bytecode (20 0 0 1 2 0 3 1 3 0 2 1 4 0 2 52 1 0 6 48 1 17 1 20 5 0 16 0 2 52 6 0 2 51 7 0 1 1 51 8 0 1 1 48 3 5 16 1 50)} {:library (sx signals-web) :op "import"}) :bytecode (1 0 0 112 5 1 1 0 112 5 51 3 0 128 2 0 5 51 5 0 128 4 0 5 51 7 0 128 6 0 5 51 9 0 128 8 0 5 51 11 0 128 10 0 5 51 13 0 128 12 0 5 1 14 0 112 50)))
+    :constants ("with-marsh-scope" {:upvalue-count 0 :arity 2 :constants ("list" "with-island-scope" {:upvalue-count 1 :arity 1 :constants ("append!") :bytecode (18 0 16 0 52 0 0 2 50)} "dom-set-data" "sx-marsh-disposers") :bytecode (52 0 0 0 17 2 20 1 0 51 2 0 1 2 16 1 48 2 5 20 3 0 16 0 1 4 0 16 2 49 3 50)} "dispose-marsh-scope" {:upvalue-count 0 :arity 1 :constants ("dom-get-data" "sx-marsh-disposers" "for-each" {:upvalue-count 0 :arity 1 :constants ("cek-call") :bytecode (16 0 2 52 0 0 2 50)} "dom-set-data") :bytecode (20 0 0 16 0 1 1 0 48 2 17 1 16 1 33 24 0 51 3 0 16 1 52 2 0 2 5 20 4 0 16 0 1 1 0 2 49 3 32 1 0 2 50)} "emit-event" {:upvalue-count 0 :arity 3 :constants ("dom-dispatch") :bytecode (20 0 0 16 0 16 1 16 2 49 3 50)} "on-event" {:upvalue-count 0 :arity 3 :constants ("dom-on") :bytecode (20 0 0 16 0 16 1 16 2 49 3 50)} "bridge-event" {:upvalue-count 0 :arity 4 :constants ("effect" {:upvalue-count 4 :arity 0 :constants ("dom-on" {:upvalue-count 2 :arity 1 :constants ("event-detail" "cek-call" "list" "reset!") :bytecode (20 0 0 16 0 48 1 17 1 18 0 33 15 0 18 0 16 1 52 2 0 1 52 1 0 2 32 2 0 16 1 17 2 20 3 0 18 1 16 2 49 2 50)}) :bytecode (20 0 0 18 0 18 1 51 1 0 0 2 0 3 48 3 17 0 16 0 50)}) :bytecode (20 0 0 51 1 0 1 0 1 1 1 3 1 2 49 1 50)} "resource" {:upvalue-count 0 :arity 1 :constants ("signal" "dict" "loading" "data" "error" "promise-then" "cek-call" {:upvalue-count 1 :arity 1 :constants ("reset!" "dict" "loading" "data" "error") :bytecode (20 0 0 18 0 1 2 0 4 1 3 0 16 0 1 4 0 2 52 1 0 6 49 2 50)} {:upvalue-count 1 :arity 1 :constants ("reset!" "dict" "loading" "data" "error") :bytecode (20 0 0 18 0 1 2 0 4 1 3 0 2 1 4 0 16 0 52 1 0 6 49 2 50)}) :bytecode (20 0 0 1 2 0 3 1 3 0 2 1 4 0 2 52 1 0 6 48 1 17 1 20 5 0 16 0 2 52 6 0 2 51 7 0 1 1 51 8 0 1 1 48 3 5 16 1 50)} {:library (sx signals-web) :op "import"}) :bytecode (51 1 0 128 0 0 5 51 3 0 128 2 0 5 51 5 0 128 4 0 5 51 7 0 128 6 0 5 51 9 0 128 8 0 5 51 11 0 128 10 0 5 1 12 0 112 50)))

shared/static/wasm/sx_browser.bc.wasm.js

@@ -1792,7 +1792,7 @@
             blake2_js_for_wasm_create: blake2_js_for_wasm_create};
    }
    (globalThis))
-({"link":[["runtime-0db9b496",0],["prelude-d7e4b000",0],["stdlib-23ce0836",[]],["re-9a0de245",[2]],["sx-42ed14c8",[2,3]],["jsoo_runtime-f96b44a8",[2]],["js_of_ocaml-651f6707",[2,5]],["dune__exe__Sx_browser-acaac3c1",[2,4,6]],["std_exit-10fb8830",[2]],["start-f808dbe1",0]],"generated":(b=>{var
+({"link":[["runtime-0db9b496",0],["prelude-d7e4b000",0],["stdlib-23ce0836",[]],["re-9a0de245",[2]],["sx-7ec49d05",[2,3]],["jsoo_runtime-f96b44a8",[2]],["js_of_ocaml-651f6707",[2,5]],["dune__exe__Sx_browser-acaac3c1",[2,4,6]],["std_exit-10fb8830",[2]],["start-f808dbe1",0]],"generated":(b=>{var
 c=b,a=b?.module?.export||b;return{"env":{"caml_ba_kind_of_typed_array":()=>{throw new
 Error("caml_ba_kind_of_typed_array not implemented")},"caml_exn_with_js_backtrace":()=>{throw new
 Error("caml_exn_with_js_backtrace not implemented")},"caml_int64_create_lo_mi_hi":()=>{throw new