PHP host shell cleanup and docs

ext/php/run.php

@@ -9,7 +9,6 @@ declare(strict_types=1);
  * Usage:
  *   php run.php run <bundle.arboricx> <arg> [arg ...]
  *   php run.php inspect <bundle.arboricx>
- *   php run.php repl
  *
  * The "run" command:
  *   1. Reads the .arboricx bundle as raw bytes
@@ -27,71 +26,52 @@ require __DIR__ . '/src/functions.php';
 require __DIR__ . '/src/codecs.php';
 require __DIR__ . '/src/kernel.php';
 
-use function Arboricx\{app, apply_, reduce, ofString, ofNumber, ofBytes, ofList,
+use function Arboricx\{app, reduce, ofString, ofNumber, ofBytes, ofList,
-    formatTree, decodeResult, unwrapResult,
+    formatTree, unwrapResult, unwrapHostValue, decodeHostPayload,
-    unwrapHostValue, decodeHostPayload,
-    isLeaf, isStem, isFork,
-    HOST_STRING_TAG, HOST_NUMBER_TAG, HOST_BOOL_TAG,
-    HOST_LIST_TAG, HOST_BYTES_TAG, HOST_TREE_TAG,
     getRunArboricxToString};
 
 // ── Commands ─────────────────────────────────────────────────────────────────
 
-function debugTime(string $label): void
+function readBundle(string $path): string
 {
-    static $start = null;
+    if (!file_exists($path)) {
-    static $last = null;
+        fwrite(STDERR, "Error: bundle not found: $path\n");
-    $now = microtime(true);
+        exit(1);
-    if ($start === null) {
-        $start = $now;
-        $last = $now;
     }
-    fwrite(STDERR, sprintf("[%.3fs +%.3fs] %s\n", $now - $start, $now - $last, $label));
+    $bytes = file_get_contents($path);
-    $last = $now;
+    if ($bytes === false) {
+        fwrite(STDERR, "Error: could not read bundle: $path\n");
+        exit(1);
+    }
+    return $bytes;
 }
 
 function cmdRun(string $bundlePath, array $args): void
 {
-    debugTime('start');
+    $bundleBytes = readBundle($bundlePath);
-
-    if (!file_exists($bundlePath)) {
-        fwrite(STDERR, "Error: bundle file not found: $bundlePath\n");
-        exit(1);
-    }
-    $bundleBytes = file_get_contents($bundlePath);
-    debugTime('read bundle bytes');
-    if ($bundleBytes === false) {
-        fwrite(STDERR, "Error: could not read bundle file: $bundlePath\n");
-        exit(1);
-    }
 
     $kernel = getRunArboricxToString();
-    debugTime('loaded kernel');
     if ($kernel === null) {
-        fwrite(STDERR, "Error: runArboricxToString kernel not configured (empty ternary string)\n");
+        fwrite(STDERR, "Error: runArboricxToString kernel not configured\n");
-        fwrite(STDERR, "Set KERNEL_RUN_ARBORICX_TO_STRING constant in kernel.php\n");
         exit(1);
     }
 
     $bundleTree = ofBytes($bundleBytes);
-    debugTime('encoded bundle bytes');
 
     $argTrees = [];
     foreach ($args as $arg) {
         $argTrees[] = encodeArg($arg);
     }
     $argsTree = ofList($argTrees);
-    debugTime('encoded args');
 
+    // Kernel application: runArboricxToString bundle args
     $expr = app(app($kernel, $bundleTree), $argsTree);
-    debugTime('built expression');
-
     fwrite(STDERR, "Reducing kernel application...\n");
     $result = reduce($expr, 1_000_000_000);
-    debugTime('reduced kernel application');
 
+    // The kernel returns an ok/err pair.  On ok, the value is a
+    // Host ABI envelope: Fork(tag_number, payload_tree).
     [$kind, $value, $rest] = unwrapResult($result);
-    debugTime('unwrapped result');
     if ($kind === 'error') {
         fwrite(STDERR, "Error detail: $rest\n");
         exit(1);
@@ -105,11 +85,9 @@ function cmdRun(string $bundlePath, array $args): void
     }
 
     [$tag, $payload] = unwrapHostValue($value);
-    debugTime('unwrapped host value');
 
     try {
         $decoded = decodeHostPayload($tag, $payload);
-        debugTime('decoded payload');
         echo $decoded['value'] . "\n";
     } catch (\Throwable $e) {
         fwrite(STDERR, "Host ABI decode error: " . $e->getMessage() . "\n");
@@ -118,34 +96,14 @@ function cmdRun(string $bundlePath, array $args): void
     }
 }
 
-/**
- * Encode a command-line argument into a Tree Calculus value.
- *
- * - Numeric strings (digits only) → tree number
- * - Everything else → tree string
- */
 function encodeArg(string $arg): int
 {
-    if (ctype_digit($arg) || ($arg !== '0' && preg_match('/^-?\d+$/', $arg))) {
+    return ctype_digit($arg) ? ofNumber((int)$arg) : ofString($arg);
-        return ofNumber((int)$arg);
-    }
-    return ofString($arg);
 }
 
 function cmdInspect(string $bundlePath): void
 {
-    // Minimal inspection: just read the bundle as bytes and print its size.
+    $bundleBytes = readBundle($bundlePath);
-    // Full parsing is done by the kernel, not the host shell.
-    if (!file_exists($bundlePath)) {
-        fwrite(STDERR, "Error: bundle file not found: $bundlePath\n");
-        exit(1);
-    }
-    $bundleBytes = file_get_contents($bundlePath);
-    if ($bundleBytes === false) {
-        fwrite(STDERR, "Error: could not read bundle file: $bundlePath\n");
-        exit(1);
-    }
-
     $bytes = strlen($bundleBytes);
     echo "Bundle: $bundlePath\n";
     echo "Size: $bytes bytes\n";
@@ -179,61 +137,6 @@ function cmdInspect(string $bundlePath): void
     }
 }
 
-function cmdRepl(): void
-{
-    echo "Arboricx PHP REPL\n";
-    echo "Commands:\n";
-    echo "  run <bundle> [args...]   — Run a bundle\n";
-    echo "  inspect <bundle>         — Inspect a bundle\n";
-    echo "  exit                     — Exit\n";
-    echo "\n";
-
-    $kernel = getRunArboricxToString();
-    if ($kernel === null) {
-        fwrite(STDERR, "Warning: kernel not configured\n");
-    }
-
-    while (true) {
-        $prompt = "arboricx> ";
-        fwrite(STDOUT, $prompt);
-        $line = trim(fgets(STDIN));
-        if ($line === '' || $line === 'exit' || $line === 'quit') {
-            break;
-        }
-
-        $parts = preg_split('/\s+/', $line, 2);
-        if (!$parts) {
-            continue;
-        }
-
-        $cmd = $parts[0];
-        switch ($cmd) {
-            case 'run':
-                if (!isset($parts[1])) {
-                    fwrite(STDERR, "Usage: run <bundle> [args...]\n");
-                    break;
-                }
-                $cmdRun($parts[1], array_slice($parts, 2));
-                break;
-            case 'inspect':
-                if (!isset($parts[1])) {
-                    fwrite(STDERR, "Usage: inspect <bundle>\n");
-                    break;
-                }
-                cmdInspect($parts[1]);
-                break;
-            case 'help':
-                echo "Commands:\n";
-                echo "  run <bundle> [args...]   — Run a bundle\n";
-                echo "  inspect <bundle>         — Inspect a bundle\n";
-                echo "  exit                     — Exit\n";
-                break;
-            default:
-                fwrite(STDERR, "Unknown command: $cmd\n");
-        }
-    }
-}
-
 // ── Main ─────────────────────────────────────────────────────────────────────
 
 $argv = $_SERVER['argv'] ?? [];
@@ -244,7 +147,6 @@ if ($argc < 2) {
     echo "\nUsage:\n";
     echo "  php run.php run <bundle.arboricx> [args...]\n";
     echo "  php run.php inspect <bundle.arboricx>\n";
-    echo "  php run.php repl\n";
     exit(0);
 }
 
@@ -264,11 +166,8 @@ switch ($command) {
         }
         cmdInspect($argv[2]);
         break;
-    case 'repl':
-        cmdRepl();
-        break;
     default:
         echo "Unknown command: $command\n";
-        echo "Usage: php run.php run|inspect|repl ...\n";
+        echo "Usage: php run.php run|inspect ...\n";
         exit(1);
 }

ext/php/src/codecs.php

@@ -54,6 +54,9 @@ function toList(int $tree): array
     return [true, $rest];
 }
 
+/**
+ * Strings are lists of byte values (each character encoded as a number tree).
+ */
 function ofString(string $s): int
 {
     $bytes = [];
@@ -104,6 +107,12 @@ function unwrapResult(int $tree): array
     return $isTrue ? ['ok', $value, $rest] : ['err', $value, $rest];
 }
 
+/**
+ * Host ABI tag constants.
+ *
+ * The kernel wraps successful results in a host value envelope:
+ *   Fork(tag_number, payload_tree)
+ */
 const HOST_TREE_TAG   = 0;
 const HOST_STRING_TAG = 1;
 const HOST_NUMBER_TAG = 2;
@@ -129,26 +138,6 @@ function isBool(int $tree): bool
     return isLeaf($tree) || (isStem($tree) && isLeaf(stemChild($tree)));
 }
 
-function isNumber(int $tree): bool
-{
-    [$ok, $_] = toNumber($tree);
-    return $ok;
-}
-
-function isList(int $tree): bool
-{
-    [$ok, $_] = toList($tree);
-    return $ok;
-}
-
-function isString(int $tree): bool
-{
-    [$ok, $elements] = toList($tree);
-    if (!$ok) return false;
-    foreach ($elements as $elem) if (!isNumber($elem)) return false;
-    return true;
-}
-
 function decodeHostPayload(int $tag, int $payload): array
 {
     switch ($tag) {
@@ -178,26 +167,4 @@ function decodeHostPayload(int $tag, int $payload): array
     }
 }
 
-function decodeResult(int $tree): string
-{
-    $tree = reduce($tree);
-    if (isLeaf($tree)) return 't';
 
-    [$ok, $str] = toString($tree);
-    if ($ok && $str !== '') {
-        $valid = true;
-        for ($i = 0; $i < strlen($str); $i++) {
-            $n = ord($str[$i]);
-            if ($n < 32 || $n > 126) { $valid = false; break; }
-        }
-        if ($valid) return '"' . $str . '"';
-    }
-
-    [$ok, $num] = toNumber($tree);
-    if ($ok) return (string)$num;
-
-    [$ok, $xs] = toList($tree);
-    if ($ok) return '[' . implode(', ', array_map(fn($x) => decodeResult($x), $xs)) . ']';
-
-    return formatTree($tree);
-}

ext/php/src/functions.php

@@ -5,27 +5,26 @@ declare(strict_types=1);
 namespace Arboricx;
 
 /**
- * Arena-backed Tree Calculus representation.
+ * Arena-backed Tree Calculus graph.
  *
- * Node refs are ints:
+ * Nodes are integers (refs) into four parallel arrays:
- *   0 = Leaf
+ *   tag 0 = Leaf
  *   tag 1 = Stem(child)
  *   tag 2 = Fork(left, right)
- *   tag 3 = App(function, argument) -- evaluator-internal thunk
+ *   tag 3 = App(function, argument)  -- evaluator thunk
- *   tag 4 = Ind(target)             -- update-in-place indirection
+ *   tag 4 = Ind(target)              -- update-in-place indirection for sharing
+ *
+ * Using ints instead of objects keeps the hot path allocation-free
+ * and lets us do cheap pointer-equality (same ref == same subtree).
  */
-
 $GLOBALS['ARB_TAG'] = [0 => 0];
 $GLOBALS['ARB_A']   = [0 => 0];
 $GLOBALS['ARB_B']   = [0 => 0];
 $GLOBALS['ARB_NEXT'] = 1;
-$GLOBALS['ARB_CONS_CACHE'] = [];
 
 function spendFuel(int &$fuel): void
 {
-    if ($fuel <= 0) {
+    if ($fuel <= 0) throw new \RuntimeException('fuel exhausted');
-        throw new \RuntimeException('fuel exhausted');
-    }
     $fuel--;
 }
 
@@ -38,14 +37,10 @@ function newNode(int $tag, int $a, int $b = 0): int
     return $id;
 }
 
-function updateInd(int $node, int $target): void
+/**
-{
+ * Chase indirection (tag 4) chains to the real node.
-    if ($node === 0 || $node === $target) return;
+ * Self-loops are treated as terminal to avoid infinite loops.
-    $GLOBALS['ARB_TAG'][$node] = 4;
+ */
-    $GLOBALS['ARB_A'][$node] = $target;
-    $GLOBALS['ARB_B'][$node] = 0;
-}
-
 function deref(int $t): int
 {
     while ($t !== 0 && ($GLOBALS['ARB_TAG'][$t] ?? -1) === 4) {
@@ -56,63 +51,43 @@ function deref(int $t): int
     return $t;
 }
 
+/**
+ * Overwrite a node with an indirection to its reduced form.
+ * This short-circuits future reads so shared sub-terms are only
+ * reduced once.
+ */
+function setInd(int $o, int $t): void
+{
+    if ($o !== $t) {
+        $GLOBALS['ARB_TAG'][$o] = 4;
+        $GLOBALS['ARB_A'][$o] = $t;
+    }
+}
+
 function leaf(): int { return 0; }
-function stem(int $child): int { return newNode(1, $child); }
+function stem(int $c): int { return newNode(1, $c); }
-function fork(int $left, int $right): int { return newNode(2, $left, $right); }
+function fork(int $l, int $r): int { return newNode(2, $l, $r); }
-function appNode(int $f, int $x): int { return newNode(3, $f, $x); }
+function app(int $f, int $x): int { return newNode(3, $f, $x); }
-function tree(): int { return 0; }
 
 function tag(int $t): int { $t = deref($t); return $GLOBALS['ARB_TAG'][$t] ?? -1; }
-function argA(int $t): int { $t = deref($t); return $GLOBALS['ARB_A'][$t]; }
-function argB(int $t): int { $t = deref($t); return $GLOBALS['ARB_B'][$t]; }
-
 function isLeaf(int $t): bool { return deref($t) === 0; }
 function isStem(int $t): bool { return tag($t) === 1; }
 function isFork(int $t): bool { return tag($t) === 2; }
 function isApp(int $t): bool { return tag($t) === 3; }
-function isTree(int $t): bool { $tag = tag($t); return $tag === 0 || $tag === 1 || $tag === 2; }
-function isTerm(int $t): bool { $tag = tag($t); return $tag === 0 || $tag === 1 || $tag === 2 || $tag === 3; }
 
-function stemChild(int $t): int { return argA($t); }
+function stemChild(int $t): int { $t = deref($t); return $GLOBALS['ARB_A'][$t]; }
-function forkLeft(int $t): int { return argA($t); }
+function forkLeft(int $t): int { $t = deref($t); return $GLOBALS['ARB_A'][$t]; }
-function forkRight(int $t): int { return argB($t); }
+function forkRight(int $t): int { $t = deref($t); return $GLOBALS['ARB_B'][$t]; }
-function appFunc(int $t): int { return argA($t); }
+function appFunc(int $t): int { $t = deref($t); return $GLOBALS['ARB_A'][$t]; }
-function appArg(int $t): int { return argB($t); }
+function appArg(int $t): int { $t = deref($t); return $GLOBALS['ARB_B'][$t]; }
-
-function app(int $f, int $x): int { return appNode($f, $x); }
-
-function newStemFast(int $child, array &$TAG, array &$A, array &$B): int
-{
-    $id = $GLOBALS['ARB_NEXT']++;
-    $TAG[$id] = 1;
-    $A[$id] = $child;
-    $B[$id] = 0;
-    return $id;
-}
-
-function newForkFast(int $left, int $right, array &$TAG, array &$A, array &$B): int
-{
-    $id = $GLOBALS['ARB_NEXT']++;
-    $TAG[$id] = 2;
-    $A[$id] = $left;
-    $B[$id] = $right;
-    return $id;
-}
-
-function newAppFast(int $f, int $x, array &$TAG, array &$A, array &$B): int
-{
-    $id = $GLOBALS['ARB_NEXT']++;
-    $TAG[$id] = 3;
-    $A[$id] = $f;
-    $B[$id] = $x;
-    return $id;
-}
-
-function apply_(int $a, int $b, int $fuel = 100_000_000_000_000_000): int
-{
-    return reduce(app($a, $b), $fuel);
-}
 
+/**
+ * Reduce a term to weak-head normal form (WHNF).
+ *
+ * The evaluator is iterative (no PHP stack growth) and reduces
+ * left-to-right: function first, then argument when needed.
+ * Fuel prevents infinite loops on divergent terms.
+ */
 function reduce(int $term, int $fuel = 100_000_000_000_000_000): int
 {
     return whnf($term, $fuel);
@@ -125,122 +100,71 @@ function whnf(int $term, int &$fuel): int
     $B   =& $GLOBALS['ARB_B'];
 
     while (true) {
-        // deref term
+        $term = deref($term);
-        while ($term !== 0 && $TAG[$term] === 4) {
+        if ($TAG[$term] !== 3) return $term;
-            $term = $A[$term];
-        }
-
-        if ($TAG[$term] !== 3) {
-            return $term;
-        }
 
         $orig = $term;
         $f = whnf($A[$term], $fuel);
         $x = $B[$term];
 
-        // deref function result
+        $f = deref($f);
-        while ($f !== 0 && $TAG[$f] === 4) {
-            $f = $A[$f];
-        }
         $ftag = $TAG[$f];
 
         // apply Leaf b = Stem b
         if ($f === 0) {
-            $result = newStemFast($x, $TAG, $A, $B);
+            $r = newNode(1, $x); setInd($orig, $r); return $r;
-            if ($orig !== $result) { $TAG[$orig] = 4; $A[$orig] = $result; $B[$orig] = 0; }
-            return $result;
         }
 
         // apply (Stem a) b = Fork a b
         if ($ftag === 1) {
-            $result = newForkFast($A[$f], $x, $TAG, $A, $B);
+            $r = newNode(2, $A[$f], $x); setInd($orig, $r); return $r;
-            if ($orig !== $result) { $TAG[$orig] = 4; $A[$orig] = $result; $B[$orig] = 0; }
-            return $result;
         }
 
-        if ($ftag !== 2) {
+        if ($ftag !== 2) throw new \RuntimeException('apply: function did not reduce to tree');
-            throw new \RuntimeException('apply: function did not reduce to tree');
-        }
 
         $left = whnf($A[$f], $fuel);
         $right = $B[$f];
-
+        $left = deref($left);
-        // deref left
-        while ($left !== 0 && $TAG[$left] === 4) {
-            $left = $A[$left];
-        }
         $ltag = $TAG[$left];
 
         // apply (Fork Leaf a) _ = a
         if ($left === 0) {
-            $term = $right;
+            $term = $right; setInd($orig, $term); spendFuel($fuel); continue;
-            if ($orig !== $term) { $TAG[$orig] = 4; $A[$orig] = $term; $B[$orig] = 0; }
-						spendFuel($fuel);
-            continue;
         }
 
         // apply (Fork (Stem a) b) c = (a c) (b c)
         if ($ltag === 1) {
-            $term = newAppFast(
+            $term = newNode(3, newNode(3, $A[$left], $x), newNode(3, $right, $x));
-                newAppFast($A[$left], $x, $TAG, $A, $B),
+            setInd($orig, $term); spendFuel($fuel); continue;
-                newAppFast($right, $x, $TAG, $A, $B),
-                $TAG, $A, $B
-            );
-            if ($orig !== $term) { $TAG[$orig] = 4; $A[$orig] = $term; $B[$orig] = 0; }
-						spendFuel($fuel);
-            continue;
         }
 
-        if ($ltag !== 2) {
+        if ($ltag !== 2) throw new \RuntimeException('apply: invalid Fork left child');
-            throw new \RuntimeException('apply: invalid Fork left child');
-        }
 
         $arg = whnf($x, $fuel);
-        while ($arg !== 0 && $TAG[$arg] === 4) {
+        $arg = deref($arg);
-            $arg = $A[$arg];
-        }
         $atag = $TAG[$arg];
 
         // apply (Fork (Fork a b) c) Leaf = a
         if ($arg === 0) {
-            $term = $A[$left];
+            $term = $A[$left]; setInd($orig, $term); spendFuel($fuel); continue;
-            if ($orig !== $term) { $TAG[$orig] = 4; $A[$orig] = $term; $B[$orig] = 0; }
-						spendFuel($fuel);
-            continue;
         }
 
         // apply (Fork (Fork a b) c) (Stem u) = b u
         if ($atag === 1) {
-            $term = newAppFast($B[$left], $A[$arg], $TAG, $A, $B);
+            $term = newNode(3, $B[$left], $A[$arg]);
-            if ($orig !== $term) { $TAG[$orig] = 4; $A[$orig] = $term; $B[$orig] = 0; }
+            setInd($orig, $term); spendFuel($fuel); continue;
-						spendFuel($fuel);
-            continue;
         }
 
         // apply (Fork (Fork a b) c) (Fork u v) = (c u) v
         if ($atag === 2) {
-            $term = newAppFast(
+            $term = newNode(3, newNode(3, $right, $A[$arg]), $B[$arg]);
-                newAppFast($right, $A[$arg], $TAG, $A, $B),
+            setInd($orig, $term); spendFuel($fuel); continue;
-                $B[$arg],
-                $TAG, $A, $B
-            );
-            if ($orig !== $term) { $TAG[$orig] = 4; $A[$orig] = $term; $B[$orig] = 0; }
-						spendFuel($fuel);
-            continue;
         }
 
         throw new \RuntimeException('apply: argument did not reduce to tree');
     }
 }
 
-function normalize(int $term, int &$fuel): int
-{
-    $term = whnf($term, $fuel);
-    if (isStem($term)) return stem(normalize(stemChild($term), $fuel));
-    if (isFork($term)) return fork(normalize(forkLeft($term), $fuel), normalize(forkRight($term), $fuel));
-    return $term;
-}
-
 function same_tree(int $a, int $b): bool
 {
     $a = deref($a); $b = deref($b);
@@ -253,13 +177,6 @@ function same_tree(int $a, int $b): bool
     return false;
 }
 
-function typeTag(int $t): string
-{
-    return match (tag($t)) {
-        0 => 'leaf', 1 => 'stem', 2 => 'fork', 3 => 'app', 4 => 'ind', default => 'unknown'
-    };
-}
-
 function formatTree(int $t, int $depth = 0): string
 {
     $t = deref($t);

ext/php/src/kernel.php

@@ -5,160 +5,49 @@ declare(strict_types=1);
 namespace Arboricx;
 
 /**
- * kernel.php — Hardcoded tricu kernel entrypoints.
+ * Kernel loader.
  *
- * The kernel is the self-hosted Arboricx runtime written in Tree Calculus,
+ * The kernel is the self-hosted Arboricx runtime compiled to a raw Tree
- * compiled to a raw Tree Calculus term. We hardcode it as a **ternary string**
+ * Calculus term.  It is shipped as a ternary string and parsed on demand.
- * and parse it on demand.
  *
- * Ternary string format (from Research.hs toTernaryString):
+ * Ternary string format (matches Research.hs toTernaryString):
- *   '0' → Leaf
+ *   '0'        → Leaf
- *   '1' ++ rest → Stem(parse(rest))
+ *   '1' rest   → Stem(parse(rest))
- *   '2' ++ rest → Fork(parse(rest), parse(rest))
+ *   '2' l r    → Fork(parse(l), parse(r))
- *
- * The Kernel class holds these constants and exposes them as Tree values.
  */
 
-use function Arboricx\{leaf, stem, fork, isLeaf, isStem, isFork};
+use function Arboricx\{leaf, stem, fork};
 
-// ── Kernel constants ────────────────────────────────────────────────────────
-
-// ── File loading ────────────────────────────────────────────────────────────
-
-/**
- * Load a kernel ternary string from a .ternary file.
- *
- * Convention: ext/php/src/kernel_<name>.ternary
- *
- * @param string $name  e.g. 'run_arboricx_to_string'
- * @return string The ternary string, or '' if file not found
- */
 function loadKernelTernary(string $name): string
 {
-    // Determine the base directory: go up from this file to ext/php/src/
+    $file = __DIR__ . '/' . $name . '.ternary';
-    $dir = dirname(__FILE__);
+    if (!file_exists($file)) return '';
-    $file = $dir . '/' . $name . '.ternary';
+    $content = file_get_contents($file);
-    if (file_exists($file)) {
+    return $content !== false ? trim($content) : '';
-        $content = file_get_contents($file);
-        if ($content !== false) {
-            return trim($content);
-        }
-    }
-    return '';
 }
 
-// ── Kernel constants (fallbacks — actual values loaded from .ternary files) ─
-
-/**
- * runArboricxToString — the primary Host ABI entrypoint.
- *
- * This is the compiled Tree Calculus term for:
- *
- *   runArboricxToString = (bs args :
- *     bindResult (runArboricxArgsByName [] bs args)
- *       (value rest :
- *         wrapHostValue hostString? hostString value rest))
- *
- * Loaded from ext/php/src/kernel_run_arboricx_to_string.ternary
- * if it exists, otherwise falls back to the constant below.
- *
- * @var string
- */
-const KERNEL_RUN_ARBORICX_TO_STRING = '';
-
-/**
- * runArboricxByNameToString — named-export variant.
- *
- *   runArboricxByNameToString = (nameBytes bs args : ...)
- *
- * Loaded from ext/php/src/kernel_run_arboricx_by_name_to_string.ternary
- * if it exists, otherwise falls back to the constant below.
- *
- * @var string
- */
-const KERNEL_RUN_ARBORICX_BY_NAME_TO_STRING = '';
-
-// ── Parser ──────────────────────────────────────────────────────────────────
-
-/**
- * Parse a ternary string into a Tree Calculus value.
- *
- * Grammar:
- *   term → '0' → Leaf
- *        → '1' term → Stem(term)
- *        → '2' term term → Fork(term, term)
- *
- * @param string $s  The ternary string to parse
- * @param int    &$pos  Current position (passed by reference)
- * @return int The parsed Tree value node id
- */
 function parseTernary(string $s, int &$pos = 0): int
 {
     if ($pos >= strlen($s)) {
         throw new \RuntimeException('parseTernary: unexpected end of string');
     }
-
+    $char = $s[$pos++];
-    $char = $s[$pos];
-    $pos++;
-
     return match ($char) {
         '0' => leaf(),
         '1' => stem(parseTernary($s, $pos)),
         '2' => fork(parseTernary($s, $pos), parseTernary($s, $pos)),
-        default => throw new \RuntimeException(
+        default => throw new \RuntimeException("parseTernary: unexpected char '$char' at position $pos"),
-            "parseTernary: unexpected char '$char' at position $pos"
-        ),
     };
 }
 
-// ── Kernel accessors ────────────────────────────────────────────────────────
-
-/**
- * Get the runArboricxToString kernel tree.
- *
- * Tries loading from ext/php/src/kernel_run_arboricx_to_string.ternary first,
- * then falls back to the KERNEL_RUN_ARBORICX_TO_STRING constant.
- *
- * Returns the parsed Tree Calculus value, or null if not configured.
- */
 function getRunArboricxToString(): ?int
 {
-    // Try file first
     $term = loadKernelTernary('kernel_run_arboricx_to_string');
-    if ($term === '') {
+    if ($term === '') return null;
-        $term = KERNEL_RUN_ARBORICX_TO_STRING;
-    }
-    if ($term === '') {
-        return null;
-    }
     $pos = 0;
     $tree = parseTernary($term, $pos);
     if ($pos !== strlen($term)) {
-        throw new \RuntimeException('kernel ternary has trailing data: parsed ' . $pos . ' of ' . strlen($term) . ' bytes');
+        throw new \RuntimeException("kernel ternary has trailing data: parsed $pos of " . strlen($term) . ' bytes');
-    }
-    return $tree;
-}
-
-/**
- * Get the runArboricxByNameToString kernel tree.
- *
- * Tries loading from ext/php/src/kernel_run_arboricx_by_name_to_string.ternary
- * first, then falls back to the KERNEL_RUN_ARBORICX_BY_NAME_TO_STRING constant.
- */
-function getRunArboricxByNameToString(): ?int
-{
-    // Try file first
-    $term = loadKernelTernary('kernel_run_arboricx_by_name_to_string');
-    if ($term === '') {
-        $term = KERNEL_RUN_ARBORICX_BY_NAME_TO_STRING;
-    }
-    if ($term === '') {
-        return null;
-    }
-    $pos = 0;
-    $tree = parseTernary($term, $pos);
-    if ($pos !== strlen($term)) {
-        throw new \RuntimeException('kernel ternary has trailing data: parsed ' . $pos . ' of ' . strlen($term) . ' bytes');
     }
     return $tree;
 }